Energy Conservation Program: Test Procedures for Central Air Conditioners and Heat Pumps

DEPARTMENT OF ENERGY

10 CFR Parts 429 and 430

[Docket No. EERE-2016-BT-TP-0029]

RIN 1904-AD71

Energy Conservation Program: Test Procedures for Central Air Conditioners and Heat Pumps

AGENCY:

Office of Energy Efficiency and Renewable Energy, Department of Energy.

ACTION:

Supplemental notice of proposed rulemaking.

SUMMARY:

The U.S. Department of Energy (DOE) proposes to revise its test procedures for central air conditioners and heat pumps (CAC/HP) established under the Energy Policy and Conservation Act. DOE published several proposals in a November 2015 supplemental notice of proposed rulemaking (SNOPR). DOE finalized some of the proposed test procedure amendments in a June 2016 final rule. This SNOPR proposes additional revisions to some of the amendments proposed in the past notices and proposes some additional amendments. Specifically, this SNOPR proposes two sets of amendments to the test procedure: Amendments to appendix M that would be required as the basis for making efficiency representations starting 180 days after final rule publication; and amendments as part of a new appendix M1 that would be the basis for making efficiency representations as of the compliance date for any amended energy conservation standards. Broadly speaking, the proposed amendments address the off-mode test procedures, clarifications on test set-up and fan delays, limits to gross indoor fin surface area for valid combinations, external static pressure conditions for testing, clarifications on represented values for CAC/HP that are distributed in commerce with multiple refrigerants, and the methodology for testing and calculating heating performance. DOE does not expect the proposed changes to appendix M to change measured efficiency. However, DOE has determined that the proposed procedures in new appendix M1 would change measured efficiency. DOE welcomes comments from the public on any subject within the scope of this test procedure rulemaking.

DATES:

DOE will accept comments, data, and information regarding this supplemental notice of proposed rulemaking (SNOPR) no later than September 23, 2016. See section V, “Public Participation,” for details.

DOE will hold a public meeting on Friday, August 26, 2016, from 10 a.m. to 2 p.m., in Washington, DC. The meeting will also be broadcast as a webinar. See section V, Public Participation, for webinar registration information, participant instructions, and information about the capabilities available to webinar participants.

ADDRESSES:

The public meeting will be held at the U.S. Department of Energy, Forrestal Building, Room 1E-245, 1000 Independence Avenue SW., Washington, DC 20585.

Any comments submitted must identify the Test Procedure SNOPR for central air conditioners and heat pumps, and provide docket number EERE-2016-BT-TP-0029 and/or regulatory information number (RIN) number 1904-AD 71. Comments may be submitted using any of the following methods:

(1)

Federal eRulemaking Portal:

www.regulations.gov

. Follow the instructions for submitting comments.

(2)

Email: CACHeatPump2016 TP0029@ee.doe.gov

Include the docket number and/or RIN in the subject line of the message.

(3)

Mail:

Appliance and Equipment Standards Program, U.S. Department of Energy, Building Technologies Office, Mailstop EE-5B, 1000 Independence Avenue SW., Washington, DC 20585-0121. If possible, please submit all items on a CD, in which case it is not necessary to include printed copies.

(4)

Hand Delivery/Courier:

Appliance and Equipment Standards Program, U.S. Department of Energy, Building Technologies Office, 950 L'Enfant Plaza, SW., 6th Floor, Washington, DC 20024. Telephone: (202) 586-6636. If possible, please submit all items on a CD, in which case it is not necessary to include printed copies.

For detailed instructions on submitting comments and additional information on the rulemaking process, see section V of this document (Public Participation).

Docket:

The docket, which includes

Federal Register

notices, comments, and other supporting documents/materials, is available for review at

www.regulations.gov

. All documents in the docket are listed in the

www.regulations.gov

index. However, some documents listed in the index, such as those containing information that is exempt from public disclosure, may not be publicly available.

The docket Web page can be found at

https://www.regulations.gov/docket?D=EERE-2016-BT-TP-0029

. The docket Web page will contain simple instructions on how to access all documents, including public comments, in the docket. See section V for information on how to submit comments through

www.regulations.gov

.

FOR FURTHER INFORMATION CONTACT:

Ashley Armstrong, U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Program, EE-5B, 1000 Independence Avenue SW., Washington, DC 20585-0121. Telephone: (202) 586-6590. Email:

Ashley.Armstrong@ee.doe.gov

.

Johanna Jochum, U.S. Department of Energy, Office of the General Counsel, GC-33, 1000 Independence Avenue SW., Washington, DC 20585-0121. Telephone: (202) 287-6307. Email:

Johanna.Jochum@hq.doe.gov

.

For further information on how to submit a comment, review other public comments and the docket, or participate in the public meeting, contact the Appliance and Equipment Standards Program staff at (202) 586-6636 or by email:

CACHeatPump2016TP0029@ee.doe.gov

.

SUPPLEMENTARY INFORMATION:

DOE is not proposing to incorporate any new standards by reference in this supplemental notice of proposed rulemaking.

Table of Contents

I. Authority and Background

A. Authority

B. Background

II. Synopsis of the Supplemental Notice of Proposed Rulemaking

III. Discussion

A. Testing, Rating, and Compliance of Basic Models of Central Air Conditioners and Heat Pumps

1. Representation Accommodation

2. Highest Sales Volume Requirement

3. Determination of Certified Rating for Multi-Split, Multi-Circuit, and Multi-Head Mini-Split Systems

4. Service Coil Definition

5. Efficiency Representations of Split-Systems for Multiple Refrigerants

6. Representation Limitations for Independent Coil Manufacturers

7. Reporting of Low-Capacity Lockout for Air Conditioners and Heat Pumps With Two-Capacity Compressors

8. Represented Values of Cooling Capacity

B. Proposed Amendments to Appendix M Testing To Determine Compliance With the Current Energy Conservation Standards

1. Measurement of Off Mode Power Consumption: Time Delay for Units With Self-Regulating Crankcase Heaters

2. Refrigerant Pressure Measurement Instructions for Cooling and Heating Heat Pumps

3. Revised EER and COP Interpolation Method for Units Equipped With Variable Speed Compressors

4. Outdoor Air Enthalpy Method Test Requirements

5. Certification of Fan Delay for Coil-Only Units

6. Normalized Gross Indoor Fin Surface Area Requirements for Split Systems

7. Modification to the Test Procedure for Variable-Speed Heat Pumps

8. Clarification of the Requirements of Break-in Periods Prior to Testing

9. Modification to the Part Load Testing Requirement of VRF Multi-Split Systems

10. Modification to the Test Unit Installation Requirement of Cased Coil Insulation and Sealing

C. Appendix M1 Proposal

1. Minimum External Static Pressure Requirements

2. Default Fan Power for Rating Coil-Only Units

3. Revised Heating Load Line Equation

4. Revised Heating Mode Test Procedure for Units Equipped With Variable Speed Compressors

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Order 12866

B. Review Under the Regulatory Flexibility Act

C. Review Under the Paperwork Reduction Act of 1995

D. Review Under the National Environmental Policy Act of 1969

E. Review Under Executive Order 13132

F. Review Under Executive Order 12988

G. Review Under the Unfunded Mandates Reform Act of 1995

H. Review Under the Treasury and General Government Appropriations Act, 1999

I. Review Under Executive Order 12630

J. Review Under Treasury and General Government Appropriations Act, 2001

K. Review Under Executive Order 13211

L. Review Under Section 32 of the Federal Energy Administration Act of 1974

M. Description of Materials Incorporated by Reference

V. Public Participation

A. Attendance at the Public Meeting

B. Procedure for Submitting Prepared General Statements for Distribution

C. Conduct of the Public Meeting

D. Submission of Comments

E. Issues on Which DOE Seeks Comment

VI. Approval of the Office of the Secretary

I. Authority and Background

A. Authority

Title III, Part B

1

of the Energy Policy and Conservation Act of 1975 (“EPCA” or “the Act”), Public Law 94-163 (42 U.S.C. 6291-6309, as codified) sets forth a variety of provisions designed to improve energy efficiency and established the Energy Conservation Program for Consumer Products Other Than Automobiles.

2

These products include central air conditioners and central air conditioning heat pumps,

3

(single-phase

4

with rated cooling capacities less than 65,000 British thermal units per hour (Btu/h))), which are the focus of this SNOPR. (42 U.S.C. 6291(1)-(2), (21) and 6292(a)(3))

1

For editorial reasons, Part B was codified as Part A in the U.S. Code.

2

All references to EPCA in this document refer to the statute as amended through the Energy Efficiency Improvement Act of 2015, Public Law 114-11 (Apr. 30, 2015).

3

This notice uses the term “CAC/HP” to refer specifically to central air conditioners (which include heat pumps) as defined by EPCA. 42 U.S.C. 6291(21.)

4

Where this notice uses the term “CAC/HP”, they are in reference specifically to central air conditioners and heat pumps as defined by EPCA.

Under EPCA, DOE's energy conservation program generally consists of four parts: (1) Testing; (2) labeling; (3) Federal energy conservation standards; and (4) certification, compliance, and enforcement. The testing requirements consist of test procedures that manufacturers of covered products must use as the basis of: (1) Certifying to DOE that their products comply with applicable energy conservation standards adopted pursuant to EPCA, and (2) making other representations about the efficiency of those products. (42 U.S.C. 6293(c); 42 U.S.C. 6295(s)) Similarly, DOE must use these test procedures to determine whether covered products comply with any relevant standards promulgated under EPCA. (42 U.S.C. 6295(s))

EPCA sets forth criteria and procedures DOE must follow when prescribing or amending test procedures for covered products. (42 U.S.C. 6293(b)(3)) EPCA provides, in relevant part, that any test procedures prescribed or amended under this section shall be reasonably designed to produce test results which measure the energy efficiency, energy use, or estimated annual operating cost of a covered product during a representative average use cycle or period of use, and shall not be unduly burdensome to conduct.

Id.

In addition, if DOE determines that a test procedure amendment is warranted, it must publish proposed test procedures and offer the public an opportunity to present oral and written comments on them. (42 U.S.C. 6293(b)(2)) Finally, in any rulemaking to amend a test procedure, DOE must determine to what extent, if any, the amended test procedure would alter the measured energy efficiency of any covered product as determined under the existing test procedure. (42 U.S.C. 6293(e)(1))

The Energy Independence and Security Act of 2007 (EISA 2007), Public Law 110-140, amended EPCA to require that, at least once every 7 years, DOE must review test procedures for all covered products and either amend the test procedures (if the Secretary determines that amended test procedures would more accurately or fully comply with the requirements of 42 U.S.C. 6293(b)(3)) or publish a notice in the

Federal Register

of any determination not to amend a test procedure. (42 U.S.C. 6293(b)(1)(A))

DOE's existing test procedures for CAC/HP adopted pursuant to these provisions appear under Title 10 of the Code of Federal Regulations (CFR) part 430, subpart B, appendix M (“Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps”). These procedures establish the currently permitted means for determining energy efficiency and annual energy consumption for CAC/HP. Some of the amendments proposed in this SNOPR will alter the measured efficiency, as represented in the regulating metrics of seasonal energy efficiency ratio (SEER), energy efficiency ratio (EER), and heating seasonal performance factor (HSPF). These amendments are proposed as part of a new appendix M1. Use of the test procedure changes proposed in this notice as part of a new appendix M1, if adopted, would become mandatory to demonstrate compliance if the existing energy conservation standards are revised. (42 U.S.C. 6293(e)(2)) In revising the energy conservation standards in a separate rulemaking, DOE would create a cross-walk from the existing standards under the current test procedure to what the standards would be if tested using the revised test procedure.

On December 19, 2007, the President signed the Energy Independence and Security Act of 2007 (EISA 2007), Public Law 110-140, which contains numerous amendments to EPCA. Section 310 of EISA 2007 established that the Department's test procedures for all covered products must account for standby mode and off mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) For CAC/HP, standby mode is incorporated into the SEER and HSPF metrics, while off mode power consumption is separately regulated. This SNOPR includes proposals relevant to the determination of both SEER and HSPF (including standby mode) and off mode power consumption. DOE would then use the cross-walked equivalent of the existing standard as the baseline for its standards analysis to prevent backsliding as required under 42 U.S.C. 6295(o)(1).

B. Background

DOE initiated a round of test procedure revisions for CAC/HP by

publishing a notice of proposed rulemaking in the

Federal Register

on June 2, 2010 (June 2010 NOPR; 75 FR 31224). Subsequently, DOE published several supplemental notices of proposed rulemaking (SNOPRs) on April 1, 2011 (April 2011 SNOPR; 76 FR 18105), on October 24, 2011 (October 2011 SNOPR: 76 FR 65616), and on November 9, 2015 (November 2015 SNOPR; 80 FR 69278) in response to comments received and to address additional needs for test procedure revisions. The June 2010 NOPR and the subsequent SNOPRs addressed a broad range of test procedure issues. On June 8, 2016, DOE published a test procedure final rule (June 2016 final rule) that finalized test procedure amendments associated with many but not all of these issues. 81 FR 36992.

On November 5, 2014, DOE published a request for information for energy conservation standards (ECS) for CAC/HP (November 2014 ECS RFI). 79 FR 65603. In response, several stakeholders provided comments suggesting that DOE amend the current test procedure. The November 2015 SNOPR addressed those test procedure-related comments, but, as mentioned in this preamble, not all of the related issues were resolved in the June 2016 final rule.

On July 14, 2015, DOE published a notice of intent to form a Working Group to negotiate a NOPR for energy conservation standards for CAC/HP and requested nominations from parties interested in serving as members of the Working Group. 80 FR 40938. The Working Group, which ultimately consisted of 15 members in addition to one member from Appliance Standards and Rulemaking Federal Advisory Committee (ASRAC), and one DOE representative, identified a number of issues related to testing and certification and made several recommendations that are being addressed in the proposals of this SNOPR. DOE believes proposed changes are consistent with the intent of the Working Group.

This SNOPR addresses proposals and comments from two rulemakings: (1) Stakeholder comments and proposals regarding the CAC test procedure (CAC TP: Docket No. EERE-2009-BT-TP-0004); and (2) stakeholder comments and proposals regarding the CAC energy conservation standard from the Working Group (CAC ECS: Docket No. EERE-2014-BT-STD-0048). Comments received through documents located in the test procedure docket are identified by “CAC TP” preceding the comment citation. Comments received through documents located in the energy conservation standard docket (EERE-2014-BT-STD-0048) are identified by “CAC ECS” preceding the comment citation. Further, comments specifically received during the CAC/HP ECS Working Group meetings are identified by “CAC ECS: ASRAC Public Meeting” preceding the comment citation.

II. Synopsis of the Supplemental Notice of Proposed Rulemaking

In this SNOPR, DOE proposes revising the certification requirements and test procedure for CAC/HP based on public comment on various published materials and the ASRAC negotiation process discussed in section I.B. In this SNOPR, DOE proposes two sets of changes: One set of proposed changes to Appendix M effective 30 days after publication of a final rule and required for testing and determining compliance with current energy conservation standards; and another set of proposed changes to create a new Appendix M1 that would be used for testing to demonstrate compliance with any amended energy conservation standards (agreed to be January 1, 2023 by the Working Group in the CAC rulemaking negotiations (CAC ECS: ASRAC Term Sheet, No. 76)). DOE requests comment on whether representations in accordance with Appendix M1 should be permitted prior to the compliance date of any amended energy conservation standards. DOE does not expect the proposed changes to Appendix M to change measured efficiency. However, DOE has determined that the proposed procedures in the new Appendix M1 would change measured efficiency.

In this SNOPR, DOE proposes the following changes to certification requirements:

(1) Certification of the indoor fan off delay used for coil-only tests.

(2) Codifying the CAC/HP ECS Working Group's recommendation regarding delayed implementation of testing to demonstrate compliance with amended energy conservation standards;

(3) Relaxing the requirement that a split system's tested combination be a high sales volume combination;

(4) Revising requirements for certification of multi-split systems in light of the proposed adoption of multiple categories of duct pressure drop that the indoor units can provide;

(5) Making explicit certain provisions of the service coil definition;

(6) Certification of separate individual combinations within the same basic model for each refrigerant that can be used in a model of split system outdoor unit without voiding the warranty; and

(7) Certification of details regarding the indoor units with which unmatched outdoor units are tested.

DOE proposes the following changes to Appendix M:

(1) Establishment of a 4-hour or 8-hour delay time before the power measurement for units that require the outdoor temperature setting to reach thermal equilibrium;

(2) A limit on the internal volume of lines and devices connected to measure pressure at refrigerant circuit locations where the refrigerant state can switch from liquid to vapor for different test operating conditions;

(3) Requiring bin-by-bin EER and coefficient of performance (COP) interpolations for all variable speed units, to calculate performance at intermediate compressor speeds;

(4) Requiring a 30-minute test without the outside-air apparatus connected (a “non-ducted” test) to be the official test as part of all cooling and heating mode tests which use the outdoor air enthalpy method as the secondary measurement; and

(5) Imposing indoor coil size limits for split system ratings.

DOE proposes the following provisions for new Appendix M1:

(1) New higher external static pressure requirements for all units, including unique minimum external static pressure requirements for mobile home systems, ceiling-mount and wall-mount systems, low and mid-static multi-split systems, space-constrained systems, and small-duct, high-velocity systems;

(2) A unique default fan power for rating mobile home coil-only units and new default fan power for all other coil-only units;

(3) Revisions to the heating load line equation in the calculation of HSPF; and

(4) Amendments to the test procedures for variable speed heat pumps that change speed at lower ambient temperatures and a 5 °F heating mode test option for calculating full-speed performance below 17 °F.

If adopted, the test procedures proposed in this SNOPR to appendix M for subpart B to 10 CFR part 430 pertaining to the efficiency of CAC/HP would be effective 30 days after publication in the

Federal Register

(referred to as the “effective date”). Pursuant to EPCA, manufacturers of covered products would be required to use the applicable test procedure as the basis for determining that their products comply with the applicable energy conservation standards. 42 U.S.C. 6295(s)) On or after 180 days after publication of a final rule, any representations made with respect to the

energy use or efficiency of CAC/HPs would be required to be made in accordance with the results of testing pursuant to the amended test procedures. (42 U.S.C. 6293(c)(2))(42 U.S.C. 6293(c)(2))

If adopted, the test procedures proposed in this SNOPR for appendix M1 to subpart B of 10 CFR part 430 pertaining to the efficiency of CAC/HP would be effective 30 days after publication in the

Federal Register

. The appendix M1 procedures would be required to be used as the basis for determining that CAC/HP comply with any amended energy conservation standards (if adopted in the concurrent CAC/HP energy conservation standards rulemaking) and for representing efficiency as of the compliance date for those amended energy conservation standards.

As noted in section I.A, 42 U.S.C. 6293(e) requires DOE to determine to what extent, if any, the proposed test procedure would alter the measured energy efficiency and measured energy use. DOE has determined that some of the proposed amendments in the new Appendix M1 would result in a change in measured energy efficiency and measured energy use for CAC/HP. DOE is conducting a separate rulemaking to amend the energy conservation standards for CAC/HP, which will take into account the test procedure revisions in Appendix M1. (CAC ECS: Docket No. EERE-2014-BT-STD-0048)

III. Discussion

This section discusses the revisions to the certification requirements and test procedure that DOE proposes in this SNOPR.

A. Testing, Rating, and Compliance of Basic Models of Central Air Conditioners and Heat Pumps

1. Representation Accommodation

The CAC/HP ECS Working Group made certain recommendations related to the Appendix M1 test procedure, with a recommended compliance date of January 1, 2023, for representations based on Appendix M1. (Docket No. EERE-2014-BT-STD-0048, No. 76, Recommendation #7) While the June 2016 Test Procedure Final Rule adopted mandatory testing requirements for representations of all basic models [81 FR at 37050-37051; 10 CFR 429.16(b)(2)(i)], the Working Group recommended several accommodations for representations for split systems:

○ DOE will implement the following accommodation for representative values of split system air conditioners and heat pumps based on the M1 methodology:

○ By January 1, 2023, manufacturers of single-split systems must validate an AEDM that is representative of the amended M1 test procedure by:

Testing a single-unit sample for 20-percent of the basic models certified.

The predicted performance as simulated by the AEDM must be within 5 percent of the performance resulting from the test of each of the models.

Although DOE will not require that a full complement of testing be completed by January 1, 2023, manufacturers are responsible for ensuring their representations are appropriate and that the models being distributed in commerce meet the applicable standards (without a 5% tolerance).

○ By January 1, 2023, manufacturers must either determine representative values for each combination of single-split-system CAC/HP based on the M1 test procedures using a validated AEDM or through testing and the applicable sampling plan.

○ By January 1, 2023, manufacturers of multi-split, multi-circuit, or multi-head mini-split systems must determine representative values for each basic model through testing and the applicable sampling plan.

○ By July 1, 2024, each model of condensing unit of split system CAC/HP must have at least 1 combination whose rating is based on testing using the M1 test procedure and the applicable sampling plan.

(Docket No. EERE-2014-BT-STD-0048, No. 76, Recommendation #10)

DOE proposes to implement these recommendations, in their entirety, in 10 CFR 429.16 and 429.70.

2. Highest Sales Volume Requirement

The CAC/HP ECS Working Group recommended that DOE implement the following requirements for single-split-system air conditioners and suggested implementing regulatory text:

• Every combination distributed in commerce must be rated.

○ Every single-stage and two-stage condensing unit distributed in commerce (other than a condensing unit for a 1-to-1 mini split) must have at least 1 coil-only rating that is representative of the least efficient coil distributed in commerce with a particular condensing unit.

• Every condensing unit distributed in commerce must have at least 1 tested combination.

○ For single-stage and two-stage condensing units (other than condensing units for a 1-to-1 mini split), this must be a coil-only combination.

• All other combinations distributed in commerce for a given condensing unit may be rated based on the application of an AEDM or testing in accordance with the applicable sampling plan.

(Docket No. EERE-2014-BT-STD-0048, No. 76, Recommendation #7)

DOE addressed the first and third bullets in a final rule published on June 8, 2016, (June 2016 final rule), but at that time declined to implement the second bullet, which recommends removing the requirement that the tested combination be the highest sales volume combination (HSVC). DOE also received comments from non-working group members regarding this requirement. JCI commented that the current language used in Appendix M denoting the HSVC match cannot be determined with exact statistics and that it actually inhibits the adoption of new and promising advancements in product design. (CAC TP: JCI, No. 66 at p. 4) In contrast, Unico commented that, as an indoor coil manufacturer, it believes it to be important that the outdoor unit manufacturer continue to test and rate the HSVC, as this is an integral requirement for their AEDM to maintain accuracy. (CAC TP: Unico, No. 63 at p. 2)

DOE believes the CAC/HP ECS Working Group recommendation adequately addresses JCI's concern about using the HSVC as a tested combination. In response to Unico, DOE notes that the requirements adopted in the June 2016 final rule require independent coil manufacturers (ICMs) to test their own equipment. It is the ICM's own responsibility to ensure the accuracy of its AEDMs. ICMs may conduct additional testing or work with outdoor unit manufacturers (OUMs) as needed to do so. For these reasons, DOE is proposing to remove the requirement that the tested combination be the HSVC. DOE proposes to apply the requirements as recommended by the CAC/HP ECS Working Group to all single-split-system air conditioners and heat pumps, including space-constrained and small-duct, high-velocity, distributed in commerce by an OUM.

3. Determination of Certified Rating for Multi-Split, Multi-Circuit, and Multi-Head Mini-Split Systems

In the June 2016 final rule, DOE modified the testing requirements for multi-head mini-split systems and multi-split systems, and added similar requirements for testing multi-circuit systems. DOE also clarified that these requirements apply to variable refrigerant flow (VRF) systems that are

single-phase and less than 65,000 Btu/h.

5

For all multi-split, multi-circuit, and multi-head mini-split systems, DOE required that, at a minimum, each model of outdoor unit must be tested as part of a tested combination (as defined at 10 CFR 430.2) that includes only non-ducted indoor units. For any models of outdoor units also sold with ducted indoor units, a second “tested combination” including only ducted indoor units must be tested. DOE also allowed for manufacturers to rate a mixed non-ducted/ducted combination as the mean of the represented values for the tested non-ducted and ducted combinations, and allowed manufacturers to test and rate specific individual combinations as separate basic models, even if they share the same model of outdoor unit. 81 FR 37003-37005 (June 8, 2016)

5

A VRF system is a multi-split system with at least three compressor capacity stages, but most VRF systems have variable-speed compressors.

DOE also added a requirement that for any models of outdoor units also sold with models of small-duct, high velocity (SDHV) indoor units, a “tested combination” composed entirely of SDHV indoor units must be used for testing and rating. However, such a system must be certified as a different basic model. Finally, DOE allowed mix-match ratings for SDHV and other non-ducted or ducted indoor units based on an average of the ratings of the two individual indoor unit types. 81 FR 37004 (June 8, 2016)

In the June 2010 NOPR, DOE had proposed lower minimum external static pressure (ESP) requirements for ducted multi-split systems (75 FR at 31232), and in the November 2015 SNOPR, DOE proposed to implement these requirements using the term “short duct systems,” which could refer to multi-split, multi-head mini-split, or multi-circuit systems with indoor units that produce a limited level of external static pressure. 80 FR at 69314 (Nov. 9, 2015). In response to the SNOPR, DOE received several comments regarding its terminology and testing requirements related to short-duct systems as well as requests for changing terminology and testing requirements to include low-static and mid-static systems, as recommended in the CAC/HP ECS Working Group Term Sheet. Therefore in the June 2016 final rule, DOE maintained the existing ducted system terminology and is addressing the earlier comments from stakeholders and recommendations from the Working Group in this SNOPR.

Unico supported DOE's definition of short-ducted systems which would create four indoor unit types for multi-split systems: Short-ducted (previously described as “ducted”), conventional ducted, SDHV-ducted, and non-ducted. (CAC TP: Unico, No. 63 at p. 11) In the Term Sheet, the CAC/HP ECS Working Group recommended that DOE define “low-static system” and “mid-static system” as discussed in section III.C.1. (CAC ECS: Docket No. EERE-2014-BT-STD-0048, No. 76 at p. 1-2) These systems are essentially sub-categories of DOE's earlier proposal for short-ducted systems.

In addition, several stakeholders commented that multi-split systems may also be paired with models of conventional ducted indoor units. UTC/Carrier commented that some manufacturers also offer ducted units with external static pressure capabilities greater than 0.65 in w.c., the maximum external static pressure proposed by the Working Group for mid-static ducted units and recommended that DOE also include a requirement for separate multi-split system ratings with these “standard” ducted indoor units. (CAC TP: UTC/Carrier, No. 62 at p. 3-4)

Rheem commented that the definition of multi-split system is not limited to a specific duct configuration and that testing of all possible duct configurations should be considered. Rheem further commented that the testing requirements should be the same as single-split systems using conventional ducted indoor units because multi-split systems duct losses are the same as the standard single-split system. (CAC TP: Rheem, No. 69 at p. 5)

NEEA and NPCC commented that multi-split systems paired with more conventional blower coil indoor units should be testable with the external static pressure conditions specified for conventional blower coil units. (CAC TP: NEEA and NPCC, No. 64 at p. 3-4)

The California IOUs commented that additional testing is needed to ensure that the AEDM gives accurate ratings for all of the possible combinations when an outdoor unit of a multi-split system is paired with a conventional central forced air indoor unit. They said that, at present, a variable speed, mini-split outdoor unit is connected to an indoor unit(s) from the same manufacturer with complex software controls that produce the variable modes of operation needed to respond to indoor and outdoor conditions. They also asserted that the indoor units can be short ducted or ductless cassettes. Finally, they commented that, if the same outdoor section is installed with a central forced air unit, it will have indoor fan operation modes and significantly different power draw and may not be representative of the nuanced behavior of the ductless and short duct components. (CAC TP: California IOUs, No. 67 at p. 3)

Given the multiple types of indoor units with which these systems can be paired, several stakeholders also made recommendations related to the testing and rating requirements.

Unico commented that multi-split ratings should be listed with homogeneous type of indoor units, which should be based on tests or a valid AEDM. Unico commented that short-ducted, conventional-ducted, SDHV-ducted and non-ducted are different types and should all be tested and rated using the appropriate test procedure for the type, and that ratings with mixed types should be an average. (CAC TP: Unico, No. 63 at p. 2)

Mitsubishi proposed that given the potential additional testing requirements presented for systems with multiple families of ducted indoor unit (low-static, mid-static and standard-static ducted), a manufacturer be allowed to produce tested combinations of all low-static, all mid-static or all standard-static indoor units, and that, if they do not wish to have separate ratings, they must use the highest rating of external static pressure to establish the tested combination. (CAC TP: Mitsubishi, No. 68 at p. 3)

Goodman suggested that any combinations of non‐ducted, low-static, mid-static and/or high-static indoor units be based on the highest static units in the combination if a single rating is to be used for all short‐ducted indoor units. In addition, Goodman stated that it believes these combinations should have the capability of being rated and certified using either test data or an AEDM. Goodman suggested that, if multiple combinations of non-ducted, low-static, mid-static and/or high-static indoor units are matched with a particular outdoor unit, the testing should be performed using the appropriate test static for each indoor unit. (CAC TP: Goodman, No. 73 at p. 13-14)

DOE supports the Working Group recommendations to replace its proposal to use the terminology short-duct with low-static and mid-static. The proposed definitions for these terms are discussed in section III.C.1. In addition, DOE agrees that multi-split, multi-head mini-split, or multi-circuit systems can include conventional ducted indoor units. DOE notes that the proposed test procedure allows selection of an appropriate external static pressure for this case.

After reviewing the comments, DOE proposes that multi-split, multi-head mini-split, and multi-circuit systems can be tested and rated with five kinds of indoor units: Non-ducted, low-static ducted, mid-static ducted, conventional ducted, or SDHV. However, DOE agrees that if a manufacturer offers an outdoor model with all five kinds of indoor units, a requirement to determine a rating through testing of each could be burdensome. Therefore, DOE proposes that, when determining represented values including certifying compliance with amended energy conservation standards, at a minimum, a manufacturer must test and rate a “tested combination” composed entirely of non-ducted units. If a manufacturer also offers the model of outdoor unit with models of low-static, mid-static, and/or conventional ducted indoor units, the manufacturer must at a minimum also test and rate a second “tested combination” with the highest static variety of indoor unit offered. The manufacturer may also choose to test and rate additional “tested combinations” composed of the lower static varieties. In each case, the manufacturer must test with the appropriate external static pressure. DOE believes that this option reduces test burden sufficiently and is not proposing use of AEDMs for these systems.

DOE proposes to maintain its requirement from the June 2016 final rule that, if a manufacturer also sells a model of outdoor unit with SDHV indoor units, the manufacturer must test and rate the SDHV system (

i.e.

test a combination with indoor units that all have SDHV pressure capability). DOE also proposes to continue to allow mix-match ratings across any two of the five varieties by taking a straight average of the ratings of the individual varieties, and to allow ratings of individual combinations through testing. As noted in the June 2016 final rule, SDHV represented values must be a separate basic model. Any represented values for a mixed system including SDHV and another style of unit must be in the same basic model as the SDHV model. Tables III.1 and III.2 summarize example represented values.

EP24AU16.000

Table III.2—Example Represented Values for SDHV Multi-Split Systems

Basic model

Individual model No. (outdoor unit)

Individual

model No.(s)

(indoor unit)

Sample size

SDHV rep. value

Mix

rep. value (ND)

Mix

rep. value (CD)

Mix

rep. value (MS)

Mix

rep. value (LS)

ABC-SDHV

ABC

* * *

6

11.50

13.25

12.75

4. Service Coil Definition

In the June 2016 final rule, to distinguish newly installed cased and uncased coils from replacement cased and uncased coils, DOE added a definition for service coils and explicitly excluded them from indoor units in the indoor unit definition:

Indoor unit

means part of a split-system air conditioner or heat pump that includes (a) an arrangement of refrigerant-to-air heat transfer coil(s) for transfer of heat between the refrigerant and the indoor air and (b) a condensate drain pan, and may or may not include (c) sheet metal or plastic parts not part of external cabinetry to direct/route airflow over the coil(s), (d) a cooling mode expansion device, (e) external cabinetry, and (f) an integrated indoor blower (

i.e.

a device to move air including its associated motor). A separate designated air mover that may be a furnace or a modular blower (as defined in Appendix AA to the subpart) may be considered to be part of the indoor unit. A service coil is not an indoor unit.

Service coil

means an arrangement of refrigerant-to-air heat transfer coil(s) and condensate drain pan that may or may not include sheet metal or plastic parts to direct/route airflow over the coil(s), external cabinetry, and/or a cooling mode expansion device, and is sold exclusively to replace an uncased coil or cased coil that has already been placed into service and is labeled accordingly.

In this SNOPR, DOE proposes to modify the adopted definition of service coil to more explicitly define what “labeled accordingly” means. Under 42 U.S.C. 6295(r), the Secretary may include any requirement which the Secretary determines is necessary to assure that each covered product to which such standard applies meets the required minimum level of energy efficiency or maximum quantity of energy use specified in such standard.

In this specific case, DOE believes service coils must be distinguished from indoor units to ensure compliance with the applicable energy conservation standards for central air conditioners and heat pumps. Specifically, DOE proposes that a manufacturer must designate a service coil as “for indoor coil replacement only” on the nameplate and in manufacturer product and technical literature. In addition, the model number for any service coil must include some mechanism (

e.g.,

an additional letter or number) for differentiating a service coil from a coil intended for an indoor unit.

5. Efficiency Representations of Split-Systems for Multiple Refrigerants

Split-system CAC/HP are required to be tested as a system. Prior to the June 2016 final rule, the condensing unit was required to be tested with “the evaporator coil that is likely to have the largest volume of retail sales with the particular model of condensing unit” (commonly referred to as the highest sales volume combination or HSVC). 10 CFR 429.16(a)(2)(ii) as of January 1, 2016. The June 2016 final rule amended the definition of “central air conditioner or central air conditioning heat pump” to recognize instances in which there is no HSVC,

i.e.,

an outdoor unit is sold separately with no matching indoor unit, referred to as an “outdoor unit with no match”. 81 FR at 36999 (June 8, 2016).

As discussed in the June 2016 final rule, outdoor units with no match are typically a result of the phase-out of HCFC-22 refrigerant. Effective January 1, 2010, the U.S. Environmental Protection Agency (EPA) banned the sale and distribution of those central air conditioning systems and heat pump systems that are designed to use HCFC-22 refrigerant. 74 FR 66450 (Dec. 15, 2009). EPA's rulemaking included an exception for the manufacture and importation of replacement components, as long as those components are not pre-charged with HCFC-22. Id. at 66459-60. Because complete HCFC-22 systems can no longer be distributed, DOE established test procedure requirements for outdoor units that have “no match,” or are not sold with a matching indoor unit, which includes those units designed to use HCFC-22.

The “no match” test procedure's goal is that the test should produce measurements of energy efficiency during a representative average use cycle (see 42 U.S.C. 6293(b)(3)) while also ensuring that any field-matched combination (including the new “no-match” outdoor unit and an existing indoor unit) meets the standard. Due to the nature of these no-match systems, however, neither the manufacturer nor DOE knows exactly what the paired system will be for an outdoor unit with no match. To ensure compliance, DOE established indoor unit specifications that are representative of a less efficient unit (representative of units on the market at the time of the change in EPA regulations) that could be paired with the given outdoor unit with no match. Specifically, DOE established a requirement that outdoor units without a matching indoor unit must be tested with an indoor unit with a normalized gross indoor fin surface (NGIFS)

6

no higher than 1.0 square inches per British thermal unit per hour (sq. in./Btu/hr). 81 FR at 37010 (June 8, 2016).

6

NGIFS is equal to normalized gross indoor fin surface (for a conventional fin-tube heat exchanger, two times fin length times fin width times the number of fins) divided by the system cooling capacity.

In response to the phase-out of HCFC-22, one course pursued by manufacturers has been to use the refrigerant R-407C, which can be used as a drop-in replacement for HCFC-22 if oil compatibility issues are addressed. (No. 1 at pp. 2-6) Because R-407C is a replacement for HCFC-22, it is possible for a central air conditioner to operate either with R-407C or with HCFC-22. Such a unit could be shipped charged with R-407C, or shipped without the refrigerant charge (

i.e.,

dry-shipped). A dry-shipped unit could then either be sold as part of an R-407C split-system, or sold as a replacement component and charged with HCFC-22. In any case, R-407C outdoor units are often marketed as replacements for HCFC-22 outdoor units, as indicated in marketing material. (Docket No. EERE-2016-BT-TP-0029-0007, -0008, -0009, -0010, -0011, -0012 and -0013) Some R-407C outdoor units are more explicitly marketed as HCFC-22 replacements than other units (

e.g.,

indicating that the outdoor unit is “compatible with R-22 coils and linesets!”). ((Docket No. EERE-2016-BT-TP-0029-0010 at p. 1).

To address instances in which the manufacturer indicates that more than one refrigerant is acceptable for use in a unit (

i.e.,

the manufacturer specifications include use of multiple refrigerants or the warranty would not be voided by the use of more than one refrigerant), DOE is proposing that a split-system air conditioner or heat pump, including outdoor unit with no match, must be certified as a separate individual combination (including outdoor unit without match as applicable) for every acceptable refrigerant. Specifically, each individual combination (including outdoor unit without match corresponding to each acceptable refrigerant) would be certified under the same basic model. DOE's existing requirements for basic models would continue to apply; therefore, if an individual combination or an outdoor unit with no match fails to meet DOE's energy conservation standards using any refrigerant indicated by the manufacturer to be acceptable, then the entire basic model would fail. DOE also proposes that manufacturers must certify the refrigerant for every individual combination that is distributed in commerce (including every outdoor unit with no match). For models where the manufacturer only indicates one acceptable refrigerant (DOE expects this to be the majority of units), this proposal would simply entail certifying to DOE the refrigerant for which the model is designed. Finally, DOE proposes that if a model of outdoor unit (used in a single-split, multi-split, multi-circuit, multi-head mini-split, and/or outdoor unit with no match system) is distributed in commerce without a specific refrigerant specified or not charged with a specified refrigerant from the point of manufacture, a manufacturer must determine the represented value as an outdoor unit with no match.

Under this proposal, if an outdoor unit manufacturer (OUM) indicates as an acceptable refrigerant for a model of outdoor unit a refrigerant that is banned for inclusion in CAC/HP distributed as systems, such as HCFC-22, the OUM would have to determine represented values (

e.g.,

SEER) for the model of outdoor unit tested as an outdoor unit with no match. Within the same basic model, the manufacturer must determine a represented value for all individual split-system combinations using the same model of outdoor unit for any acceptable refrigerants with which the model of outdoor unit can legally be sold as a system. DOE has tentatively determined that specification by an OUM as to the acceptable refrigerant indicates the ultimate use or uses for which the unit was designed and manufactured.

Inclusion of HCFC-22 as an acceptable refrigerant by the manufacturer indicates that the model of outdoor unit was designed and manufactured to be sold separately as a replacement component (

i.e.,

as a model of outdoor unit with no match), because manufacturers are prohibited from selling and distributing central air conditioning systems and heat pump systems that use HCFC-22 refrigerant,

except as replacement components (

i.e.,

outdoor units with no match).

As indicated previously in this discussion, it is DOE's understanding that the listing of acceptable refrigerants also impacts the unit's warranty. In order for a unit to remain under warranty, the unit generally must be operated and maintained as recommended by the manufacturer. If a manufacturer indicates that HCFC-22 is an acceptable refrigerant, its use in an outdoor unit would not be expected to void the warranty. Again, DOE understands conformance with the warranty to be an indication of the intended use for which a model is designed and manufactured. Additionally, DOE understands that manufacturer literature for some models may not explicitly state which refrigerants may be used without voiding the warranty and may instead generally refer to specific refrigerant characteristics for the warranty to remain valid. If for such a case, HCFC-22 meets the specified characteristics, DOE's proposal would require that the manufacturer certify, within the same basic model, an individual split-system combination or outdoor unit with no match for each refrigerant that meet these warranty criteria or characteristics.

Under the certification requirements proposed in this SNOPR, an outdoor unit for which both R-407C and HCFC-22 are acceptable refrigerants would need to be certified as a split-system combination and as an outdoor unit with no match, with representations for each. Per DOE's regulations established in the June 2016 final rule, outdoor units with no match cannot be certified using an AEDM, and the model of outdoor unit must be tested with an indoor unit meeting specified criteria. 81 FR at 37051 (June 8, 2016). Therefore, for a model of outdoor unit for which both R-407C and HCFC-22 are acceptable refrigerants, the outdoor unit with no match (with HCFC-22) must be tested and certified. In addition, DOE proposes to require that any split-system combination (with R-407C) must also be tested. The proposed certification requirements would represent the energy efficiency of an outdoor unit during a representative average use cycle for each intended sales scenario (

i.e.,

either sold as a split system and installed with a new matching indoor unit, or sold as a replacement component and installed with a legacy indoor unit).

In addition, DOE recognizes that concerns regarding warrantee coverage for a given refrigerant may not be a concern for all installers and consumers. Consequently, DOE is concerned that the lack of explicit indication that a unit is acceptable for use with HCFC-22 may not prevent installation of such units with the refrigerants, if the installers and consumers have reasonable confidence that the unit can operate with this refrigerant. Because of the similarity of HCFC-22 and R-407C and the history of CAC/HP being used interchangeably with both of these refrigerants, this issue could very well arise for any unit certified and warranted for use with R-407C. Hence, DOE proposes that any outdoor unit intended for use in a split system with R-407C,

i.e.

any unit shipped with a charge of any amount of R-407C, would also have to be rated as an outdoor unit with no match.

Nearly all outdoor units of split systems are shipped with a quantity of refrigerant charge that is close to the required charge for installation. This has been confirmed by observation of units tested by DOE. Line sets for connecting indoor units to outdoor units also are sold with an appropriate pre-charge to compensate for the different amount of charge that remains in the lines of different-length line sets. During set-up, the refrigerant charge of the assembled system is adjusted, and the pre-charging of the components limits the amount of refrigerant that is needed to be added or removed in order to match the charging conditions specified in the manufacturer's installation instructions. Because of this general practice to ship outdoor units with close to full charge, DOE considers use of a charge quantity that is much less than the charge specified by the instructions to be equivalent to shipping a unit without refrigerant. Hence, DOE proposes to require a no-match rating for outdoor units that are shipped with a charge amount such that adjustment of charge as specified in manufacturer's instructions requires addition of more than one pound of refrigerant.

As an example illustrating the certification requirement proposals discussed in this section, assume a manufacturer advertises a model of outdoor unit for use with either HCFC-22 or R-407C.

In 10 CFR 430.2 (as amended in the June 2016 final rule), DOE defines “basic model” for OUMs as “all individual combinations having the same model of outdoor unit, which means comparably performing compressor(s) [a variation of no more than five percent in displacement rate (volume per time) as rated by the compressor manufacturer, and no more than five percent in capacity and power input for the same operating conditions as rated by the compressor manufacturer], outdoor coil(s) [no more than five percent variation in face area and total fin surface area; same fin material; same tube material], and outdoor fan(s) [no more than ten percent variation in air flow and no more than twenty percent variation in power input].” According to this definition, the model of outdoor unit intended to be sold with both HCFC-22 and R-407C would represent multiple individual combinations within the same basic model. Therefore, a manufacturer has to determine a represented value for each single-split-system combination (sold for use with R-407C) as well as determine a represented value for the outdoor unit with no match (sold for use with HCFC-22).

See

10 CFR 429.16(a)(1) (as amended in the June 2016 final rule), 81 FR 36001, 37056 (June 8, 2016).

Paragraph 10 CFR 429.16(b)(2)(i) (as amended in the June 2016 final rule) details the minimum testing requirements for each basic model, specified by equipment category. In this SNOPR, DOE is proposing to further specify in that same paragraph that when a basic model spans listed categories, as in this example, multiple testing requirements apply. Therefore, the manufacturer would have to test at least one single-split-system combination as well as the model of outdoor unit with a model of coil-only indoor unit meeting the requirements of section 2.2e of Appendix M or M1 to subpart B of part 430 (

i.e.,

test as an outdoor unit with no match). Under 10 CFR 429.16(c)(1)(i) (as amended in the June 2016 final rule), any other single-split combinations within the basic model may be tested or rated using an AEDM according to the applicable requirements. 81 FR 36001, 37049 (June 8, 2016).

In the event that DOE determines a basic model is noncompliant with an applicable energy conservation standard, DOE may issue a notice of noncompliance determination that, among other things, informs the manufacturer of its obligation to cease distribution of the basic model immediately. (10 CFR 429.114(a)) Therefore, if any individual combination (including the outdoor unit with no match) fails to comply with the applicable standard, whether the combination has been tested or rated using an AEDM, the entire basic model must be removed from the market and the model of outdoor unit may not be sold at all.

DOE also notes that although the discussion in this section of the SNOPR is directly related to refrigerants, a basic model may span listed categories in

other situations. For example, as mentioned in the June 2016 final rule, a model of outdoor unit may be sold both as part of a single-split system and as part of a multi-split system. 81 FR at 37005. In this case, the manufacturer would have to determine represented values within each of these categories as required by 429.16(a)(1) and would have to meet the testing requirements for each category in 429.16(b)(2)(i). Furthermore, if an individual combination that is either a single-split or multi-split system fails to comply with the standard, the model of outdoor unit may not be sold for use in either category.

DOE also proposes to add information to the items required to be provided in certification reports to address outdoor units with no match. The general certification requirements for air conditioners and heat pumps as amended in the June 2016 final rule already apply to outdoor units with no match. These requirements include reporting of SEER, the average off mode power consumption, the cooling capacity, the region(s) in which the basic model can be sold, HSPF (for heat pumps), and EER (for air conditioners), and non-public information including indoor air volume rate for the relevant operating modes (

e.g.,

full-load cooling, part-load cooling, full-load heating). 81 FR 36991, 37053 (June 8, 2016). In this SNOPR, DOE proposes to require reporting of additional non-public information for the indoor unit that is tested with an outdoor unit with no match. This would include the indoor coil face area, depth in the direction of airflow, fin density (fins per inch), fin material, fin style (

e.g.,

wavy or louvered), tube diameter, tube material, and numbers of tubes high and deep. These additional requirements would apply to outdoor units with no match, whether or not the outdoor unit was also certified as part of an individual combination.

Issue 1:

DOE requests comment on its proposed certification requirements for outdoor units with no match. Also, DOE seeks comment on what fin style options should be considered as options for CCMS database data entry.

6. Representation Limitations for Independent Coil Manufacturers

In the June 2016 final rule, DOE discussed compliance with Federal (base national or regional) standards for CAC/HP. Specifically DOE cited a proposal in the November 2015 SNOPR to amend 10 CFR 430.32 to clarify that the least-efficient combination within each basic model must comply with the regional SEER and EER standards. 80 FR 69277, 69290 (Nov. 9, 2015). However, DOE declined to modify section 430.32 in the June 2016 final rule, instead stating that it would do so in the regional standards enforcement rulemaking. 81 FR 36991, 37012 (June 8, 2016). Instead, DOE adopted language in 10 CFR 429.16 specifying that a basic model may only be certified as compliant with a regional standard if all individual combinations within that basic model meet the regional standard for which that basic model would be certified and that an ICM cannot certify a basic model containing a representative value that is more efficient than any combination certified by an OUM containing the same outdoor unit. 81 FR at 37050.

In response to the June 2016 final rule, Advanced Distributor Products (ADP) and Lennox International submitted separate but essentially identical letters and AHRI submitted a similar letter (Docket No. EERE-2016-BT-TP-0029-0006, -0005, and -0003) stating that this language, while intended to define that ICM ratings cannot provide a means for an outdoor unit to span regions, is inconsistent with the Regional Standards ASRAC Working Group agreement (Docket No. EERE-2011-BT-CE-0077-0070). ADP, Lennox, and AHRI suggested that language proposed in the regional standards enforcement NOPR (80 FR 72389-72390), but not finalized, captured the enforcement working group intent and avoids inadvertent limitations on independent coil manufacturers. Mortex also submitted a letter (Docket No. EERE-2016-BT-TP-0029-0004) commenting on the same language, also stating that it seems inconsistent with agreements made during the Regional Standards ASRAC Working Group. Mortex suggested that the requirement be removed from the test procedure.

DOE did not adopt the language proposed in the regional standards enforcement NOPR in response to comments submitted in that rulemaking. DOE agrees, however, that the language adopted at 429.16 inadvertently constrains ICMs beyond the bounds agreed to in the Regional Standards ASRAC Working Group. Accordingly, DOE proposes to remove the sentence: “An ICM cannot certify a basic model containing a representative value that is more efficient than any combination certified by an OUM containing the same outdoor unit.” and replace it with the following language in 429.16(a)(4)(i): An ICM cannot certify an individual combination with a rating that is compliant with a regional standard if the individual combination includes a model of outdoor unit that the OUM has certified with a rating that is not compliant with a regional standard. Conversely, an ICM cannot certify an individual combination with a rating that is not compliant with a regional standard if the individual combination includes a model of outdoor unit that an OUM has certified with a rating that is compliant with a regional standard.

Issue 2:

DOE requests comment on its proposed language in 429.16 related to allowable ICM ratings and compliance with regional standards.

7. Reporting of Low-Capacity Lockout for Air Conditioners and Heat Pumps With Two-Capacity Compressors

The current SEER and HSPF equations (4.1-1 and 4.2-1) in the DOE test procedure for a CAC/HP having a two-capacity compressor require different calculations of quantities depending on whether the test unit would operate at low capacity, cycle between low and high capacity, or operate at high capacity in response to the building load (see sections 4.1.3 and 4.2.3). To determine which calculations to use for units that lock out low capacity operation at higher outdoor temperatures, the outdoor temperature at which the unit locks out low capacity operation must be known. Section 4.1.3 of Appendix M indicates that this information must be provided by the manufacturer. Similarly, a two-stage heat pump may lock out low capacity heating operation below a certain lock-out temperature, as indicated in section 4.2.3 of Appendix M. Therefore, DOE proposes to add language to require that the lock-out temperatures for such systems for both cooling and heating modes be provided in the certification report.

8. Represented Values of Cooling Capacity

In the November 2015 SNOPR, DOE proposed adding a requirement that the represented values of cooling capacity and heating capacity must be the mean of the values measured for the sample. In response, AHRI, Lennox, JCI, Ingersoll Rand, Goodman, UTC/Carrier, Nortek, and Rheem disagreed with the requirement that the represented capacity values must be the mean of the tested values, and recommended that DOE allow manufacturers to rate capacity conservatively. (CAC TP: AHRI, No. 70 at p. 10; Lennox, No. 61 at p. 8, 15; JCI, No. 66 at p. 15-16; Ingersoll Rand, No. 65 at p. 5; Goodman, No. 73 at p. 15; UTC/Carrier, No. 62 at p. 8; Nortek, No. 58 at p. 6; Rheem, No. 69 at p. 8) The commenters provided additional detail as summarized in the

June 2016 final rule. 81 FR 37014-15 (June 8, 2016).

After reviewing the comments, in the June 2016 final rule DOE required the represented value of cooling (or heating) capacity to be a self-declared value that is no less than 95 percent of the mean of the cooling (or heating) capacities measured for the units in the sample selected for testing or of the output simulated by the AEDM. DOE stated that this would allow manufacturers the flexibility to derate capacity with conservative values as requested by multiple commenters, while still providing consumers with information that is reasonably close to the performance they may expect when purchasing a system.

Id.;

10 CFR 429.16(b)(3) and 429.16(d).

Upon review, DOE has determined that the regulatory text adopted allows for unlimited overrating of capacity but only underrating of 5 percent. Consequently, in this SNOPR, DOE is proposing to revise the regulatory text in three locations (10 CFR 429.16(b)(3), 10 CFR 429.16(d), 10 CFR 429.70(e)(5)(iv)) to allow a one-sided tolerance on cooling and heating capacity that allows underrating of any amount but only overrating up to 5 percent (

i.e.,

the certified capacity must be no greater than 105 percent of the mean measured capacity or the output of the AEDM), as intended in the June 2016 final rule. As adopted in that final rule, DOE would still use the mean of the measured capacities in its enforcement provisions.

Issue 3:

DOE requests comment on its proposal to allow a one-sided tolerance on represented values of cooling and heating capacity that allows underrating of any amount but only overrating up to 5 percent.

B. Proposed Amendments to Appendix M Testing To Determine Compliance With the Current Energy Conservation Standards

In this SNOPR, DOE proposes revisions to appendix M to subpart B of 10 CFR part 430. This section provides a discussion of those proposed changes. DOE proposes to make these changes to Appendix M effective 30 days after publication of a final rule in the

Federal Register.

Representations related to the efficiency of CAC/HP basic models must be based on testing in accordance with the final rule procedures not later than 180 days following publication of the final rule.

1. Measurement of Off Mode Power Consumption: Time Delay for Units With Self-Regulating Crankcase Heaters

DOE finalized an off-mode test procedure in the June 2016 final rule. 81 FR, 36991, 37022-5 (June 8, 2016). However, DOE recognizes that the current regulations may not account for excessive variation in the test results for units with self-regulating crankcase heaters or for units where the crankcase heater power measurement could be affected by the ambient temperature. These potential variations could be due to the large thermal mass of the compressor and the resulting time required for the compressor temperature to reach equilibrium. Because the power input of a self-regulating heater would depend on the compressor temperature, the test result would depend on the temperature of the unit just prior to the test. If conducted shortly after the B test, which is one of the steady-state wet coil cooling-mode tests conducted in an 82 °F ambient temperature, the compressor would still be quite warm, and the measured power input would be significantly lower than if the test were conducted after the compressor equilibrates with the surrounding space temperature. DOE proposes further revision to the test procedure to resolve this issue. The proposal in this section would not impact the measured off-mode power input beyond potentially reducing variation in the measured result.

In the off-mode test procedure established in the June 2016 final rule, DOE established a test method for units with self-regulating crankcase heaters that called for start of the test in a room conditioned to 82 °F temperature, with the compressor at a temperature no lower than 81 °F. The room temperature is then adjusted at a rate of change of no more than 20 °F per hour to approach 72 °F for conducting a first heater power measurement, and then to approach a manufacturer-specified lower temperature, again at a rate of change no more than 20 °F per hour, before conducting the second power measurement. 81 FR at 37022 (June 8, 2016). A half-hour duration in the initial reduction in room temperature from 82 °F to 72 °F would be compliant with the prescribed 20 °F maximum temperature reduction rate. However, DOE testing shows that the time constant for compressor cooldown, or for approach to equilibrium of the power input a self-regulating crankcase heater attached to a compressor, is much longer than a half-hour. This issue would be exacerbated if the compressor has a sound blanket. Self-regulating crankcase heaters draw less power when they are warmer. Hence, if the temperature cooldown from 82 °F is initiated when the compressor is hot (

e.g.,

after running the B test), the compressor will still be very warm when the test is conducted, and the measured power input will be lower than for a test initiated with a compressor at the minimum 81 °F.

To determine the reasonable delay time for units to reach thermal equilibrium, DOE conducted tests using a 5-ton residential condensing unit. DOE connected a self-regulating crankcase heater to the compressor and measured heater power input, compressor shell temperature, and ambient temperature. DOE observed cooldown behavior and the corresponding increase in heater input power in a 60 °F environment both with and without a sound blanket covering the compressor after initially preheating the compressor to 120 °F to simulate warmup associated with refrigeration system operation. DOE used an exponential equation for the power input to the heater as a function of time to fit to the test data. The time constant for approach to equilibrium (time for the difference between the power input and the value it would attain after an infinite amount of time to drop by 63 percent) DOE observed in the tests was approximately 2 hours for tests without the sound blanket (bare shell) and 4 hours for tests with the sound blanket. DOE also observed that the crankcase heater power input generally approached to within 10 percent of its final value after passage of about two time constants (4 hours for bare-shell testing and 8 hours for sound blanket testing).

Based on the testing and analysis described in this preamble, DOE proposes adopting a time delay for testing units with self-regulating crankcase heaters or crankcase heating systems in which the heater control temperature sensor is affected by the heater. DOE proposes a 4-hour time delay for units where the compressors have no sound blanket, and an 8-hour time delay for units where the compressors do have sound blankets. The delay would take place after the room temperature reaches the lower target value and before making each of the power measurements (P

1x

and P

2x

). Also, the proposal would eliminate the 20 °F per hour room temperature reduction rate limit for any unit where ambient temperature can affect the measurement of crankcase heater power because the roughly half hour required for the temperature to transition at this rate from 82 °F to 72 °F would add unnecessarily to the compressor's equilibration time—equilibration would occur sooner if the ambient temperature more quickly drops to the final value rather than approaching it slowly.

Issue 4:

DOE seeks comments from interested parties about its proposal to impose time delays to allow approach to equilibrium for measurements of off-mode power for units with self-regulating crankcase heaters. DOE requests comment regarding the 4-hour and 8-hour delay times proposed for units without and with compressor sound blankets, respectively.

2. Refrigerant Pressure Measurement Instructions for Cooling and Heating Heat Pumps

In DOE's current test procedures at Appendix M, refrigerant pressure measurement is required when using the refrigerant enthalpy method as the secondary capacity measurement (see section 2.10.3 of 10 CFR part 430, subpart B, appendix M). Refrigerant pressure measurement is also required for some methods for setting or confirming refrigerant charge (see section 2.2.5 of 10 CFR part 430, subpart B, appendix M), unless otherwise instructed by the manufacturer's installation instructions.

DOE is aware that the pressure measurement devices may be installed at a location where the refrigerant state switches between liquid and vapor under different cooling and heating modes. In this case, the actual refrigerant charge in the unit could be different under different modes due to the transfer of refrigerant to and from the extra internal volumes in the refrigerant pressure lines, connections, and transducers or gauges.

DOE is also aware that the refrigerant charge in pressure measurement systems may affect cyclic testing. In a cooling test, the liquid refrigerant in the liquid refrigerant pressure measurement system is cooler than the refrigerant in the condenser. For a system with a fixed orifice expansion device, allowing the cooler refrigerant from the pressure measurement systems to flow into the evaporator before the fan delay ends could affect the cyclic performance.

These issues have the potential to impact test reproducibility and repeatability, in particular for small capacity mini-split heat pump systems with low system refrigerant charges, depending on the differences in internal volumes of the tubing, connections, and transducers, particularly from one laboratory to the next.

As part of the compressor calibration method, ASHRAE 37-2009 section 7.4.2 provides instructions for making refrigerant pressure measurements. For equipment not sensitive to refrigerant charge, the pressure measurement instruments may be connected via pressure measurement lines to the refrigerant lines without requiring that any preliminary tests be conducted to confirm that displacement of refrigerant into the pressure lines does not affect performance. The test standard sets a threshold for sensitivity to refrigerant charge, indicating that for equipment that is not sensitive to the charge, the refrigerant pressure lines must not affect the total charge by more than 0.5%.

To limit the amount of refrigerant charge that can transfer to and from the pressure measurement system, DOE proposes to require manufacturers to limit the total internal volume of pressure lines and pressure measurement devices connected at locations that can switch states from liquid to vapor for different operating modes or conditions. Based on the ASHRAE 37-2009 precedent, DOE selected a maximum internal volume connected at these locations that would represent at most 0.5 percent of the total system charge for the lowest-charge systems for which DOE collected information. The proposed maximum total internal volume of the pressure lines, connections and gauges would be 0.25 cubic inches per 12,000 Btu/hr certified cooling capacity. DOE selected this maximum volume based on a survey of refrigerant charge in mini-split heat pumps with capacities ranging from 9,000 to 33,000 Btu/hr.

DOE notes that the charge adjustment approach prescribed by ASHRAE 37-2009 for systems that are sensitive to refrigerant charge would not resolve the issue of displacement of refrigerant into the pressure lines because that approach is based on steady-state testing, for which the displaced refrigerant would remain in the lines. The required adjustment would add that same amount of refrigerant so that the charge actively circulating in the refrigerant circuit would be the same as if no pressure lines had been connected. In the present case, where refrigerant would be displaced between heating and cooling mode or between cycles of a cyclic test, simply adding the “missing” charge would not resolve the issue.

The internal volume of pressure measurement lines and connections can be determined using the tubing inner diameter or internal volume values found on pressure gauge or transducer manufacturer specification sheets. However, DOE is aware that the manufacturer specification sheets may not provide the internal volume of pressure gauges or pressure transducers, and they may not be easy to measure. Thus, DOE proposes to use 0.1 cubic inches as the default internal volume for each pressure transducer and 0.2 cubic inches for each pressure gauge, if internal volume is not provided in specification sheets. DOE proposes to include this requirement in section 2.2 of 10 CFR part 430, subpart B, appendix M.

Issue 5:

DOE requests comment on its proposal to limit the internal volume of pressure measurement systems for cooling/heating heat pumps where the pressure measurement location may switch from liquid to vapor state when changing operating modes and for all systems undergoing cyclic tests. DOE also requests comment specifically on (a) the proposed 0.25 cubic inch per 12,000 Btu/h maximum internal volume for such systems, and (b) the proposals for default internal volumes to assign to pressure transducers and gauges of 0.1 and 0.2 cubic inches, respectively.

3. Revised EER and COP Interpolation Method for Units Equipped With Variable Speed Compressors

In the current DOE test procedure specified in section 3.2.4 and 3.6.4 of 10 CFR part 430, subpart B, appendix M, the building load is determined as a function of temperature, for both cooling and heating. Units equipped with variable speed compressors are tested at full, intermediate and minimum speeds. In calculating SEER and HSPF for variable speed units, there are three possible scenarios: (a) When the building load requires less than the minimum-speed capacity, the unit cycles at the minimum compressor speed to meet the load; (b) when the load requires more than the maximum-speed capacity, the unit operates constantly at full load; and (c) when the unit operates at an intermediate speed to meet a building load that is between the minimum-speed and maximum-speed capacities. Three outdoor temperatures are calculated for cooling and/or heating units equipped with variable speed compressors to bound the conditions in which scenario c would apply. These three outdoor temperatures are the balance points (temperatures at which the building load and delivered capacity are equal) for operation at the tested minimum, intermediate, and full compressor speeds. For all variable speed units operating in cooling mode and non-multi-split variable speed units operating in heating mode, the unit's EER and COP are calculated using quadratic functions. These quadratic functions are determined based on the EER or COP evaluated for the three calculated outdoor temperatures representing the minimum, intermediate, and full speed balance points.

In a final rule published October 22, 2007, DOE adopted a different approach for multi-split heat pumps. 72 FR 59906 (October 2007 Final Rule). DOE determined in that final rule that the quadratic fit would not be well-suited for multi-split units because the intermediate speed initially defined for variable-speed units is not likely the peak efficiency point for multi-split units. (see 71 FR 41320, 41325 (July 20, 2006)). In addition to allowing multi-split manufacturers some flexibility in selecting intermediate speeds for testing, DOE also adopted in the October 2007 final rule a two-piece linear relationship to represent EER and COP vs. temperature, rather than the quadratic fit used for other variable-speed units. 72 FR 59906 (Oct. 22, 2007).

As discussed in section III.C.3.d, AHRI provided variable speed and two stage heat data (under a Non-Disclosure Agreement to DOE's contractor) to allow evaluation of the impact on the HSPF differential associated with the new heating load line equation. In reviewing AHRI's variable speed heat pump heating test data, DOE's contractor discovered that the quadratic interpolation in some cases provides very poor estimation of COPs in the intermediate-speed operating range—in some cases predicting higher or lower COP values than all of the measured COP results. DOE has found similar issues with prediction of the cooling EER using the quadratic function, although DOE has less cooling mode data to review, and the most egregious errors in EER prediction for cooling mode are not as bad as the observed COP errors. Nevertheless, DOE believes such issues could very well cause significant errors in calculation of SEER for variable-speed units.

In this SNOPR, DOE evaluated two alternative interpolation methods for calculating SEER and HSPF for variable-speed CAC/HP in addition to the current quadratic function approach: (1) The linear interpolation method which currently applies only to multi-split units in heating mode (section 4.2.4.2 of 10 CFR part 430, subpart B, appendix M); and (2) a bin-by-bin interpolation method. The bin-by-bin method uses interpolation of EER or COP for each temperature bin based on the estimates of capacity and power input for the specific bin temperature (EER is equal to cooling capacity divided by power input, while COP is proportional to heating capacity divided by power input). Under the bin-by-bin method, an interpolation factor is first calculated, which represents the compressor operating speed needed to achieve balance between house load and delivered capacity. For example, if, for the specific temperature bin, the heating load is between the minimum-speed capacity and the intermediate-speed capacity, the interpolation factor is equal to the difference between the heating load and the minimum-speed capacity divided by the difference between the intermediate-speed capacity and the minimum-speed capacity. This factor is then applied to the COP values to determine COP when operating at the speed needed to deliver the desired heating load. The desired load is divided by this COP to determine power input. The interpolation is between the minimum speed and the intermediate speed performance values if the load is between the minimum and intermediate-speed capacities, or between the intermediate speed and the full speed performance values, if the load is between the intermediate and full speed capacities.

DOE found that HSPFs calculated with the current quadratic method deviated from HSPFs calculated using the bin-by-bin method up to 7.4 percent and the linear interpolation method deviated up to 2.9 percent from the bin-by-bin method. Calculations conducted for cooling mode SEER showed that SEER for the quadratic method deviated from the SEER calculated for the bin-by-bin method up to 2.5 percent. DOE believes that the bin-by-bin interpolation method is the most accurate of the three approaches (

i.e.,

DOE's current quadratic approach and the two alternative approaches considered for this SNOPR), because it is based on the best estimates of performance at the different compressor speeds for the specific ambient temperature considered for each bin. Hence, DOE proposes to require use of the bin-by-bin interpolations for all variable speed units (including variable-speed multi-split and multi-head mini-split systems), to calculate performance when operating at an intermediate compressor speed to match the building cooling or heating load. Because DOE believes that the bin-by-bin method is the most accurate, DOE does not propose for all variable-speed systems to adopt the linear approach currently used for multi-split systems. DOE would implement this change by revising the intermediate speed EER and COP equations in section of 4.1.4.2 and 4.2.4.2 of appendix M of 10 CFR part 430 subpart B.

Issue 6:

DOE requests comment on the proposal to require the use of a bin-by-bin method to calculate EER and COP for intermediate-speed operation for SEER and HSPF calculations for variable-speed units.

4. Outdoor Air Enthalpy Method Test Requirements

In DOE's current test procedure in Section 2.10 of appendix M to subpart B of part 430, the outdoor air enthalpy method is an allowable secondary test method for split systems and single-package units. DOE currently requires that the outdoor air-side test apparatus be connected to the outdoor unit and used for measurements for the outdoor air enthalpy method during the “official” test. Additionally, DOE requires a preliminary test be conducted prior to conduct of the official test, in which the unit operates without the outdoor air-side test apparatus connected. After operating without the apparatus, the apparatus is connected, and the apparatus exhaust fan speed is adjusted until performance is verified as consistent with performance prior to attaching the apparatus. Specifically, the unit must operate for 30 minutes without the apparatus connected, followed by at least five consecutive readings with the apparatus connected (with measurements taken at one-minute intervals). The apparatus exhaust fan speed must be adjusted so that the averages for the evaporator and condenser temperatures, or the saturated temperatures corresponding to the measured pressures, agree within ± 0.5 °F between the tests with and without the apparatus connected. Additionally, a preliminary test is only required prior to the first steady-state cooling mode test and the first steady-state heating mode test, as long as the outdoor fan operates during all cooling mode steady-state tests at the same speed and during all heating mode steady-state tests at the same speed. However, the test procedure requires that a preliminary test be conducted prior to each cooling mode test where a different fan speed is used, and a similar requirement applies for heating mode tests.

The outdoor air enthalpy method includes two steps in order to verify the capacity determined from the indoor air enthalpy method during the official test. However, DOE is concerned that the tolerances on achieving the same condensing and evaporating conditions in the tests with and without the airflow measurement apparatus attached inherently introduces variability to the test results that could be eliminated by shifting to an official test with the apparatus not attached. DOE proposes to make such a change for the official test.

In this SNOPR, DOE proposes to require two-step measurements in the

outdoor air enthalpy method only for cooling and heating mode tests that currently require preliminary tests (

i.e.,

the first cooling mode and heating mode tests, and any cooling mode and heating mode tests where a different outdoor fan speed is used). For example, if the unit uses a different outdoor fan speed for each test, the two-step approach would be required for each test condition. On the other hand, if the unit is a single-capacity unit and the outdoor fan uses the same fixed speed for all tests, the two-step approach would be required only for the A and H1 tests. DOE proposes that for all cooling and heating mode tests, a 30-minute test be conducted without the outside-air apparatus connected (“non-ducted” test). For tests that do not require measurements for the outdoor air enthalpy method, this 30-minute test non-ducted test would constitute the official test. For tests that do require measurements using the outdoor air enthalpy method, DOE proposes to maintain the current approach, except for changing designation of what constitutes the official test. First, the current 30-minute preliminary test would be conducted without the outside-air apparatus attached (now the “non-ducted” test). Next, the outside-air apparatus would be attached. For this test, now termed the “ducted” test, the airflow would be adjusted so that condensing and evaporating conditions are matched within tolerances, and five consecutive readings would be required (as is required for the current test) to verify the primary capacity measurements. For the tests that require measurements using the outdoor air enthalpy method, DOE proposes that the following conditions must be met for the test to be considered valid:

(1) The energy balance specified in section 3.1.1 of appendix M to subpart B of part 430 is achieved for the ducted test (

i.e.,

compare the capacities determined using the indoor air enthalpy method and the outdoor air enthalpy method).

(2) The capacities determined using the indoor air enthalpy method from the ducted and non-ducted tests cannot deviate more than 2.0 percent.

If the test is valid, the non-ducted test would be used as the official measurement for the specific test condition.

DOE believes that use of the outdoor air enthalpy method for only certain tests sufficiently measures and verifies the capacity determined from the indoor air enthalpy method, and that losing the benefit of two-step verification of the capacity determined during all of the official tests is outweighed by the three following benefits to DOE's proposal:

•

Better Representativeness of Field Use.

First, attachment of an apparatus for measurements for the outdoor air enthalpy method inherently affects the airflow pattern for the condenser (for example, by blocking any potential for partial recirculation of condenser discharge air to the inlet) and adds external static pressure for the outdoor fan to overcome. While DOE's procedure requires adjustment of apparatus exhaust fan speed to achieve similar performance to operation without the outdoor air-side apparatus, there is still a tolerance on this deviation in performance. Also, it may be impossible to exactly match no-discharge-duct performance—for example, if the discharge duct blocks partial air recirculation, total condenser fan airflow may have to be reduced to achieve the same condensing temperature, thus altering the condenser fan operating point. Therefore, DOE believes that removal of the requirement to connect the outdoor air-side test apparatus during the official test would allow for performance that better matches performance in the field.

•

Improved Test Reproducibility and Repeatability.

Second, to maintain similar performance to operation without the outdoor air-side apparatus, DOE currently requires that the apparatus exhaust fan speed be adjusted. Specifically, the averages for the evaporator and condenser temperatures, or the saturated temperatures corresponding to the measured pressures, must agree within ± 0.5 °F of the averages achieved when the apparatus was disconnected. However, if the outdoor air-side apparatus is connected during the official test, two different test labs could measure evaporate and condenser temperatures that differ by up to 1.0 °F when testing the same unit. This variation could, in turn, affect the measured cooling and/or heating capacity of the unit, and therefore would change the calculated SEER and/or HSPF. DOE believes that removing the ducted test requirement from the official test would reduce this variation in performance and therefore improve the reproducibility and repeatability of its test procedure.

•

Reduced Test Burden.

Third, for cooling mode and heating mode tests requiring a preliminary test, DOE's current test procedure requires a 30-minute non-ducted test and 5-minute ducted test be conducted as part of the preliminary test, in addition to the 30-minute official test. However, in DOE's proposal, separate 30-minute tests would not be required for the preliminary and official tests—only a single 30-minute non-ducted test would be performed as the official test, assuming the required tolerances and test conditions are met. DOE expects this removal of a required test to reduce the burden of testing units with the outdoor air enthalpy method as a secondary method.

Issue 7:

DOE requests comment on its proposed modifications to requirements when using the outdoor air enthalpy method as the secondary test method, including its proposal that the official test be conducted without the outdoor air-side test apparatus connected.

5. Certification of Fan Delay for Coil-Only Units

In the cyclic dry-coil cooling-mode tests, the current regulatory text requires coil-only units to be tested with a time-delay relay. Section 3.5.1 of the current Appendix M states that the automatic controls that are normally installed with the test unit must govern the OFF/ON cycling of the air moving equipment on the indoor side. (10 CFR 430 Subpart B, App. M, 3.5.1) Under that section, the manufacturer is to control the indoor coil airflow for ducted coil-only units according to the rated ON and/or OFF delays provided by the relay. However, DOE understands that in typical installations, a time-delay relay, if it exists, would be part of the furnace function. DOE reviewed furnace product literature collected during the furnace fan rulemaking (see Docket Number EERE-2010-BT-STD-0011) representing a broad range of furnaces sold by major furnace manufacturers to determine whether they have time-delay relays available for cooling mode when installed with coil-only air conditioners. DOE found that in many furnace series, both old and new, from multiple manufacturers, cooling time delays are common, but they are exclusively used for the compressor off-cycle, and they have varying time-delay durations. Thus, DOE concludes that coil-only units are likely to be installed with time-delay relay control for cooling, but that the duration of the delay varies by furnace. DOE is proposing no change in the use of time delays for testing of coil-only units, but proposes to amend its certification report requirements to require coil-only ratings specify whether a time delay is included, and if so, the duration of the delay used. DOE would use the certified time delay for any testing to verify performance. Section 3.5.1 would indicate that the time delay used for testing of a coil-only system shall be as listed in the certification report.

Issue 8:

DOE requests comments on its proposal to require certification reports for coil-only units to indicate whether testing was conducted using a time-delay relay to provide an off-cycle time delay, and the duration of the time delay.

6. Normalized Gross Indoor Fin Surface Area Requirements for Split Systems

DOE must establish test procedures that are reasonably designed to measure energy efficiency during a representative average use cycle as determined by DOE. (42 U.S.C. 6293 (b)(3)) DOE is aware that many potential combinations of single-split-system condensing units and indoor coils could be tested even if they are not typically installed as a combination. Ratings of single-split-system coil-only combinations, for which the outdoor unit and indoor unit are not typically installed as a combination, would not be representative of an average use cycle. The CAC/HP ECS Working Group discussed this concept and the potentially undesirable impacts of rating combinations that are not distributed in commerce or installed for consumers. Specifically, the CAC/HP ECS Working Group addressed ratings based on a combination using a blower coil indoor unit consisting of a low-efficiency condensing unit paired with an indoor blower with unusually low input power, a concept the participants referred to as a “golden blower.” Such a combination would result in an inflated rating for a low-efficiency condensing unit that is not representative of its typical installed performance. (CAC ECS: ASRAC Public Meeting, No. 87 at p. 88) The concept of unrepresentative, high performance can apply to other design aspects of indoor units, such as units with an indoor coil size far larger than would be installed for the given system capacity. To help ensure that the test procedure results in ratings that are representative of average use, DOE proposes to include a provision that would prevent testing certain combinations that are not representative of single-split systems with coil-only indoor units that are commonly distributed in commerce.

Specifically, DOE proposes to limit the normalized gross indoor fin surface (NGIFS) for the indoor unit used for single-split-system coil-only tests be no greater than 2.0 square inches per British thermal unit per hour (sq.in./Btu/hr). NGIFS is equal to total fin surface multiplied by the number of fins and divided by system capacity. An NGIFS greater than 2.0 sq.in./Btu/hr indicates that the system combines a low-capacity condensing unit with a high capacity indoor coil,

e.g.,

a 1.5-ton condensing unit paired with a 5-ton indoor coil. First, a house requiring a 1.5-ton air conditioner would be expected to have a commensurately-sized furnace, and a much larger indoor coil may not fit with the furnace or the existing available space. Second, such a combination might have good rated efficiency, but would provide poor dehumidification performance, due to the elevation of coil surface temperature (potentially above incoming air dew point temperature) associated with the large coil surface area. Because of the size compatibility and poor dehumidification performance, DOE understands that systems with an NGIFS greater than 2.0 sq.in/Btu/hr are not typically installed.

DOE evaluated the NGIFS for a representative data set of single-split-system coil-only combinations currently offered in the market to set this value. DOE's dataset included close to 100 two, three, and five-ton single-split-system coil-only combinations from multiple manufacturers that represent a majority of market share and span the available range of efficiency. Testing with a NGIFS no greater than 2.0 sq.in/Btu/hr would still reflect approximately 95 percent of the split-system coil-only combinations reviewed by DOE. DOE understands a single-split-system coil-only combination with an NGIFS that exceeds 2.0 sq.in/Btu/hr to be unrepresentative because it is unlikely to be distributed in commerce, which is supported by the review of NGIFS values for numerous rated combinations, as noted previously.

Issue 9:

DOE requests comment on its proposal to limit the NGIFS of tested coil-only single-split systems to 2.0 sq.in/Btu/hr.

7. Modification to the Test Procedure for Variable-Speed Heat Pumps

In the November 2015 SNOPR, DOE proposed several changes to the test procedure for variable-speed heat pumps. First, DOE proposed that the maximum compressor speed used for the test be fixed at the absolute maximum speed at which the compressor operates for the given operating mode (heating or cooling). In other words, the maximum compressor speed used in different cooling mode test conditions would be the same, equal to the absolute maximum speed used for cooling at any operating condition. DOE proposed a similar approach for heating, allowing for a different maximum speed than for cooling. 80 FR at 69307 (Nov. 9, 2015).

The June 2016 final rule discussed comments on this proposal, several of which indicated that the compressors of variable speed heat pumps very often operate at higher speeds at colder temperatures, which can enhance measured HSPF. 81 FR at 37029 (June 8, 2016). The comments indicated that for some of these heat pumps, the compressor cannot operate in a 47 °F ambient temperature at the same full speed that it uses in a 17 °F ambient temperature. Although DOE did not in that final rule modify the test procedure to allow different compressor speeds for the full-speed tests conducted at 17 °F, 35 °F, and 47 °F ambient temperatures, DOE did acknowledge that addressing this issue would improve the test method's representation of the improved performance of variable speed heat pumps that use higher speeds at lower temperatures, indicating that consideration would be given to such a test procedure revision in the future.

7

Id.

In this SNOPR, DOE proposes such a test procedure revision.

7

The June 2016 final rule also changed the terminology for the highest compressor speed from “maximum speed” to “full speed,” as requested by several comments responding to the November 2015 SNOPR. 81 FR at 37030 (June 8, 2016).

The possible adoption of a 2 °F test for rating of variable speed heat pumps was proposed in the November 2015 SNOPR. 80 FR 69323 (Nov. 9, 2015) It was also discussed during the CAC/HP ECS Working Group meetings, ultimately leading to Recommendation #5 in the Term Sheet, that a 5 °F ambient temperature optional test be adopted for variable speed heat pumps under the new Appendix M1. (CAC ECS: ASRAC Term Sheet, No. 76 at p. 3) This proposed revision is discussed in greater detail in section III.C.4. Because the Appendix M1 test procedure changes would be required as the basis for efficiency representations on the effective date of any new energy conservation standards (January 1, 2023), the 5 °F test for variable speed heat pumps would not become an option for several years. Based on the stakeholder comments discussed in this preamble, some variable-speed heat pumps may be unable to operate as required by the appendix M procedure as finalized by the June 2016 final rule. In order to resolve this issue sooner than 2021, DOE proposes that the test procedure revisions to address it be adopted in appendix M rather than appendix M1. Hence, DOE proposes the following amendments for appendix M.

• A 47 °F full-speed test used to represent the heating capacity would be required and designated as H1

N

. However, the 47 °F full-speed test would not have to be conducted using the same compressor speed (determined based on revolutions per minute (RPM)

or power input frequency) as the full-speed tests conducted at 17 °F and 35 °F ambient temperatures, nor at the same compressor speeds used for the full-speed cooling test conducted at 95 °F. For Appendix M, the compressor speed for the 47 °F full-speed test would be at the manufacturer's discretion, except that it would have to be no lower than the speed used in the 95 °F full-speed cooling test. Prior to the June 2016 final rule amendments, the heating capacity was represented either by the H1

2

test (for which the compressor speed guidance was not explicit), or, if a manufacturer chose to conduct what was then the optional H1

N

test, this latter test (using the same compressor speed as the full-speed cooling mode test) represented the heating capacity. In the current proposal, heating capacity would be represented only by the H1

N

test, which would be mandatory, while the compressor speed would be at the manufacturer's discretion within a range from the speed used for the 95 °F full-speed cooling test to the speed used for the full-speed 17 °F test.

• The full-speed tests conducted at 17 °F and 35 °F ambient temperatures would still have to use the same speed, which would be the maximum speed at which the system controls would operate the compressor in normal operation in a 17 °F ambient temperature, although the 35 °F full-speed test is and would remain optional.

• It would be optional to conduct a second full-speed test at 47 °F ambient temperature at the same compressor speed as used for the 17 °F test, if this speed is higher than the speed used for the H1

N

test described in this preamble. This test would be designated the H1

2

test. Because DOE does not expect that an H1

N

test would ever use a higher compressor speed than used for the full-speed 17 °F test, the test procedure would not provide for this situation.

• If no 47 °F full-speed test is conducted at the same speed as used for the 17 °F full-speed test, standardized slope factors for capacity and power input would be used to estimate the performance of the heat pump for the 47 °F full-speed test point for the purpose of calculating HSPF.

• The capacity measured for the H1

N

test would be used in the calculation to determine the design heating requirement.

Development of these proposals and decisions regarding their details is explained further below.

As discussed in the June 2016 final rule, DOE believes that extrapolations of performance to lower temperatures should be based on tests conducted at the same speed and used to estimate performance where there is a good expectation that the speeds are also the same or at least not very different. Hence, DOE believes that calculation of performance below 17 °F must be based on a same-speed extrapolation (or on an interpolation using measurements for a lower-temperature test, such as for the proposed 5 °F test discussed in section III.C.4). For those heat pumps which cannot operate in the 47 °F ambient temperature at the same compressor speed used for the 17 °F full-speed test, DOE proposes use of average performance trends to represent the 47 °F test point so that a representative same-speed extrapolation can be done.

DOE evaluated the 17 °F-to-47 °F same-speed performance trends of heat pumps based on several sources including the AHRI database, data for two stage and variable speed heat pumps provided to DOE's contractor by AHRI during the CAC/HP ECS meetings, and product data sheets for 51 single-package heat pumps. The ratios for capacity and power input for the 17 °F test condition as compared to the 47 °F test condition are presented in Table III.4. The AHRI database provides capacity information for both 17 °F and 47 °F test conditions, but not power input for both. DOE did not consider variable speed models from the AHRI database in this analysis because of questions about whether the compressor speeds were the same for both test conditions for tests of these units. For the data provided by AHRI during the CAC/HP ECS meetings, DOE evaluated the two stage units and the variable speed units with a capacity ratio within a narrow range, to be sure that the results for these units were based on use of the same speed for both test conditions. Evaluation of the data for single-package units shows that they have a significantly lower capacity ratio, but roughly the same power input ratio, as compared with split systems. Consequently, DOE is proposing in this SNOPR a different standard capacity slope factor for single-package units.

Table III.3—Average Heat Pump Capacity and Power Input Ratios for 17 °F and 47 °F Tests

Data source

Capacity

ratio

(17 °F vs. 47 °F)

Power input ratio

(17 °F vs. 47 °F)

AHRI Database, Single-Stage and Two stage

Split-System

0.618

Not available.

Single-Package

0.558

Data Provided by AHRI During ASRAC Meetings:

Two stage

0.623

0.886.

Variable speed *

0.637

0.875.

Data Sheets for Single-Package Units

0.557

0.874.

* Just for VS units with capacity ratio between 0.59 and 0.67, indicating high probability that compressor speed was the same for both 17 °F and 47 °F tests.

Based on the reviewed data, DOE selected capacity ratios equal to 0.62 for split systems and 0.56 for single-package units in order to calculate capacity slope factors. Also, DOE selected 0.88 as the power input ratio to use for calculating the power input slope factor. DOE proposes adopting slope factors that would be multiplied by the capacity or power input measured for the 17 °F ambient temperature in order to obtain the slope of the evaluated parameter per degree temperature rise. For example:

Capacity Slope = Q

h

k=2

(17) * CSF

Where:

Capacity Slope is the change in capacity per change in temperature in Btu/h-°F,

Q

h

k=2

(17) is the capacity measured in the H3

2

Test in Btu/h, and

CSF is the Capacity Slope Factor in 1/°F.

The CSF is calculated from the selected capacity ratio as follows:

EP24AU16.001

Where CR is the capacity ratio.

The resulting values for the capacity slope factors are 0.0204/°F for split

systems and 0.0262/°F for single-package systems. DOE adopted a similar approach for development of the Power Slope Factor (PSF), which is calculated to be 0.00455/°F for all systems.

DOE proposes use of these slope factors for any variable speed heat pumps for which the 47 °F full-speed test cannot be conducted at the same speed (represented by RPM or power input frequency) used in the 17 °F full-speed test. The slope factors would be used for calculation of representative capacity and power for operation at 47 °F ambient temperature for the purposes of calculating HSPF.

As mentioned in this preamble, DOE proposes that the 17 °F test be conducted using the maximum speed at which the system controls would operate the compressor during normal operation in this ambient temperature. This would help to ensure that the test procedure be representative of field operation, since, for cold temperatures close to 17 °F, the heat pump would be expected to be operating at full speed to satisfy the high heating loads expected for these temperatures. Further, DOE proposes that the 35 °F full-speed test, if conducted, use the same compressor speed as the 17 °F test, so that the impact of frosting and defrost for this test is not masked by an adjustment in compressor speed.

Issue 10:

DOE requests comments on its proposal to require that full-speed tests conducted in 17 °F and 35 °F ambient temperatures use the maximum compressor speed at which the system controls would operate the compressor in normal operation in a 17 °F ambient temperatures. DOE requests comment on the proposed approach of using standardized slope factors for calculation of representative performance at 47 °F ambient temperature for heat pumps for which the 47 °F full-speed test cannot be conducted at the same speed as the 17 °F full-speed test. Further, DOE requests comment on the specific slope factors proposed, and/or data to show that different slope factors should be used.

In addition, DOE proposes that the H1

N

test, at 47 °F ambient temperature, be conducted to represent nominal heat pump heating capacity, but that there would be no specific compressor speed requirement associated with it for Appendix M, except that it be no lower than the speed used for the 95 °F full-speed cooling test. If the H1

N

test does not use the same speed as is used for the 17 °F full-speed heating test, it would affect the HSPF calculation only through its influence on the design heating requirement, since the standardized slope factors would be used to represent full-speed heat pump performance. DOE proposes that the 47 °F full-speed test used to represent heat pump capacity would use the same maximum compressor speed that the control system would use during normal operation in 47 °F ambient temperatures in Appendix M1 (see section III.C.4) However, proposing flexibility in the selection of compressor speed for the test would be more consistent with the recent approach for measuring nominal heating capacity (prior to publication of the June 2016 final rule) because compressor speed requirements on the H1

2

test may not have been clearly defined at that time (see Appendix M to subpart B of part 430 as of January 1, 2016).

Issue 11:

DOE requests comments on its proposal to allow the full speed test in 47 °F ambient temperature that is used to represent heat pump heating capacity, to use any speed that is no lower than used for the 95 °F full-speed cooling test for Appendix M.

8. Clarification of the Requirements of Break-in Periods Prior to Testing

In the June 2016 final rule, DOE maintained its proposal from the November 2015 SNOPR to allow manufacturers the option of specifying a break-in period to be conducted prior to testing under the DOE test procedure. DOE limited the optional break-in period to 20 hours, which is consistent with the test procedure final rule for commercial HVAC equipment (10 CFR 431.96). The duration of the compressor break-in period, if used, must be included in the certification report for CAC/HP (10 CFR 429.16). DOE also adopted the same provisions as the commercial HVAC rule regarding the requirement for manufacturers to record the use of a break-in period and its duration as part of the test data underlying their product certifications, the use for testing conducted by DOE of the same break-in period specified in product certifications, and use of the 20 hour break-in period for DOE testing of products certified using an AEDM. 81 FR at 37033 (Jun. 8, 2016).

Section 3.1.7 of Appendix M, “Test Sequence” indicates that manufacturers have the option to operate the equipment for a break-in period on to exceed 20 hours, and that this break-in period must be recorded in the test data underlying the certified rating if the manufacturer uses a break-in period. DOE has made reporting of the break-in period a certification report requirement. 81 FR at 37053 (June 8, 2016). Hence, the instructions to record the break-in period in the test report is not necessary in section 3.1.7. Also, DOE intends that tests conducted by third-party testing facilities should use the break-in period that is certified and proposes to modify the language to clarify that the certified break-in period is used for the test (whether conducted by a manufacturer or other party). DOE also proposes to clarify that each compressor should undergo the break-in according to the certified number of hours, for units with multiple compressors. Finally, DOE proposes to clarify that the break-in period should be conducted prior to the first 30 minutes test data collection period as required by the test methods in section 3 of Appendix M.

Issue 12:

DOE requests comments on its clarifications regarding use of break-in, including use of the certified break-in period for each compressor of the unit, regardless of who conducts the test, prior to any test period used to measure performance.

9. Modification to the Part Load Testing Requirement of VRF Multi-Split Systems

In addition to the adopted portions of the AHRI Standard 1230-2010, DOE proposed additional provisions in the November 2015 SNOPR for testing of VRF Multi-Split Systems. This included a provision adopted as part of section 2.2.3.a of Appendix M in the June 2016 final rule requiring that for part load tests, the sum of the nominal heating or cooling capacities of the operational indoor units be within 5 percent of the intended system part load heating or cooling capacity. 81 FR at 37066 (June 8, 2016). DOE recognizes the intended system part load heating or cooling capacity is not clearly defined in the test procedure and that the sum of nominal capacities of the indoor units may very well be higher than the system part load capacity during the test (since the indoor units would be expected to be operating at part load, less than their nominal capacity, during a part load test). Therefore, DOE proposes to remove this 5 percent tolerance requirement.

Issue 13:

DOE requests comments on removing from section 2.2.3.a of Appendix M the 5 percent tolerance for part load operation when comparing the sum of nominal capacities of the indoor units and the intended system part load capacity.

10. Modification to the Test Unit Installation Requirement of Cased Coil Insulation and Sealing

The June 2016 final rule provided instructions in 2.2.c of Appendix M for uncased coils, including instructions

regarding the addition of internal insulation and/or sealing consistent with manufacturer's instructions. The section ends with a requirement that no extra insulating or sealing is allowed for cased coils. This statement was intended to indicate that no extra internal insulating or sealing is allowed. DOE believes that the statement as it stands may suggest that sealing is not allowed between a cased coil and its connections to inlet and outlet ducts. To prevent such confusion, DOE proposes to remove the statement about cased coils.

Issue 14:

DOE requests comment on whether removing the statement about insulating or sealing cased coils in Appendix M, section 2.2.c would be sufficient to avoid confusion regarding whether sealing of duct connections is allowed.

C. Appendix M1 Proposal

The November 2015 SNOPR proposed to establish a new Appendix M1 to Subpart B of 10 CFR part 430, which would be required to demonstrate compliance with any new energy conservation standards. 80 FR 69278, 69397 (Nov. 9, 2015) In this SNOPR, DOE also proposes to establish a new Appendix M1. The appendix would include all of the test procedure provisions in Appendix M as finalized in the June 2016 final rule, all of the proposed changes to Appendix M that are discussed in section III.B, and all of the additional proposals discussed in this section III.C, which would be included only in the new Appendix M1. DOE proposes to make Appendix M1 mandatory for representations of efficiency starting on the compliance date of any amended energy conservation standards for CAC/HP (however, note that phase-in of testing requirements for certain proposed new requirements for split systems would be as discussed in section III.A.1).

1. Minimum External Static Pressure Requirements

Most of the CAC/HP in the United States use ductwork to distribute air in a residence, using either a fan inside the indoor unit or housed in a separate component, such as a furnace, to move the air. External static pressure (ESP) for a CAC/HP is the static pressure rise between the inlet and outlet of the indoor unit that is needed to overcome frictional losses in the ductwork. The external static pressure imposed by the ductwork affects the power consumed by the indoor fan, and therefore also affects the SEER and/or HSPF of a CAC/HP.

a. Conventional Central Air Conditioners and Heat Pumps

The current DOE test procedure

8

stipulates that certification tests for “conventional” CACs and heat pump blower coil systems (

i.e.,

CACs and heat pump blower coil systems which are not small-duct, high-velocity systems) must be performed with an external static pressure at or above 0.10 in. wc. if cooling capacity is rated at 28,800 Btu/h or less; at or above 0.15 in. wc. if cooling capacity is rated from 29,000 Btu/h to 42,500 Btu/h; and at or above 0.20 in. wc. if cooling capacity is rated at 43,000 Btu/h or more.

8

Table 3 of 10 CFR part 430 subpart B appendix M.

DOE did not propose revisions to minimum external static pressure requirements for conventional blower coil systems in the June 2010 test procedure NOPR, stating that new values and a consensus standard were not readily available.

9

75 FR 13223, 31228 (June 2, 2010). However, between the June 2010 test procedure NOPR and the November 2015 test procedure SNOPR, many stakeholders submitted comments citing data that suggested the minimum external static pressure requirements were too low and a value of 0.50 in. wc. would be more representative of field conditions. These comments are summarized in the November 2015 test procedure SNOPR. 80 FR 69317-18 (Nov. 9, 2015). Ultimately, in the November 2015 SNOPR, DOE proposed to adopt, for inclusion into 10 CFR part 430, subpart B, appendix M1, for systems other than multi-split systems and small-duct, high-velocity systems, minimum external static pressure requirements of 0.45 in. wc. for units with a rated cooling capacity of 28,800 Btu/h or less; 0.50 in. wc. for units with a rated cooling capacity from 29,000 Btu/h to 42,500 Btu/h; and 0.55 in. wc. for units with a rated cooling capacity of 43,000 Btu/h or more. DOE reviewed available field data to determine the external static pressure values it proposed in the November 2015 test procedure SNOPR. DOE gathered field studies and research reports, where publically available, to estimate field external static pressures. DOE previously reviewed most of these studies when developing test requirements for furnace fans. The 20 studies, published from 1995 to 2007, provided 1,010 assessments of location and construction characteristics of CAC and/or heat pump systems in residences, with the data collected varying by location, representation of system static pressure measurements, equipment's age, ductwork arrangement, and air-tightness.

10

79 FR 500 (Jan. 3, 2014). DOE also gathered data and conducted analyses to quantify the pressure drops associated with indoor coil and filter foulants.

11

The November 2015 test procedure SNOPR provides a detailed overview of the analysis approach DOE used to determine an appropriate external static pressure value using this data. 80 FR 69318-19 (Nov. 9, 2015). DOE did not consider revising the minimum external static pressure requirements for SDHV systems in the November 2015 test procedure SNOPR. DOE did, however, propose to establish a new category of ducted systems, short duct systems, which would have lower external static pressure requirements for testing. DOE proposed to define “short duct system” to mean ducted systems whose indoor units can deliver no more than 0.07 in. wc. external static pressure when delivering the full load air volume rate for cooling operation. 80 FR at 69314. DOE proposed in the November 2015 SNOPR to require short duct systems to be tested using the minimum external static pressure previously proposed in the June 2010 NOPR for “multi-split” systems: 0.03 in. wc. for units less than 28,800 Btu/h; 0.05 in. wc. for units between 29,000 Btu/h and 42,500 Btu/h; and 0.07 in. wc. for units greater than 43,000 Btu/h. 75 FR at 31232 (June 2, 2010)

9

In the June 2010 NOPR, DOE proposed lower minimum ESP requirements for ducted multi-split systems: 0.03 in. wc. for units less than 28,800 Btu/h; 0.05 in. wc. for units between 29,000 Btu/h and 42,500 Btu/h; and 0.07 in. wc. for units greater than 43,000 Btu/h. 75 FR at 31232 (June 2, 2010).

10

DOE has included a list of citations for these studies in the docket for the furnace fan test procedure rulemaking. The docket number for the furnace fan test procedure rulemaking is EERE-2010-BT-TP-0010.

11

Siegel, J., Walker, I., and Sherman, M. 2002. “Dirty Air Conditioners: Energy Implications of Coil Fouling” Lawrence Berkeley National Laboratory report, number LBNL-49757.

ACCA. 1995. Manual D: Duct Systems. Washington, DC, Air Conditioning Contractors of America.

Parker, D.S., J.R. Sherwin, et al. 1997. “Impact of evaporator coil airflow in air conditioning systems” ASHRAE Transactions 103(2): 395-405.

In response to the November 2015 SNOPR, Lennox supported DOE's proposal to increase the minimum test static pressure to more accurately reflect field installation conditions. Lennox recommended that this level be set to 0.50 in. wc. for all capacities, commenting that the single set point simplifies the test procedure, is consistent with levels found in field studies, and avoids compliance issues related to minimum static pressure settings based upon capacity. (CAC TP:

Lennox, No. 61 at p. 11) Lennox also commented that improvements in field practices to reduce installed static pressure in parallel with optimizing products for lower static pressures are a more effective measure to optimize field performance and reduce energy consumption. Lennox commented that products optimized for increased static pressures will likely result in increased energy consumption. (Lennox, No. 61 at p. 11) Unlike Lennox, Rheem did not agree in its comments that the assumption of poorly designed ductwork should be built into the test procedure. (CAC TP: Rheem, No. 69 at p. 16)

Many interested parties supported the proposal to increase the external static pressure requirement. NEEA and NPCC commented that the minor adjustments on either side of 0.50 in. wc. on the basis of system capacity would be a needless complication of the test procedure because NEEA and NPPC's field data does not suggest any correlation between the external static pressure a system faces and the system capacity. (CAC TP: NEEA and NPCC, No. 64 at p. 8) The California IOUs recommended that all capacities use 0.50 in. wc. to simplify testing. (CAC TP: California IOUs, No. 67 at p. 2) ACEEE, NRDC, and ASAP fully supported adopting 0.50 in. wc. for all units (in blower coil configuration), as 0.5 in. wc. would be closer to the levels found in thousands of residential duct systems tested. (CAC TP: ACEEE, NRDC, ASAP, No. 72 at p. 4)

Lennox and Rheem commented that DOE's assumption that a CAC system would be poorly maintained, such as containing fouled coils and filters, should not be built into the test procedure. (CAC TP: Lennox, No. 61 at p. 19; Rheem, No. 69 at p. 16) Lennox further commented that any accommodation for poor field conditions should be administered equitably across all product types. (CAC TP: Lennox, No. 61 at p. 19) Rheem also commented that although dirty filters and fouled coils can increase system static, Rheem considers undersized duct work as the leading cause of high pressure drop measured in field applications. (CAC TP: Rheem, No. 69 at p. 16) Rheem believed that requiring higher minimum external static pressure would reduce published ratings, which could confuse installers and consumers. Rheem commented that a new energy metric should be introduced that would distinguish ratings based on appendix M from ratings based on appendix M1. The California IOUs commented that, as shown in the ACCA Manual D,

12

the filter pressure drop value of 0.20 in. wc. is normal, and supported DOE's proposal. (CAC TP: California IOUs, No. 67 at p. 6)

12

Manual D: Residential Duct Systems.

Arlington, VA: Air Conditioning Contractors of America (ACCA).

After discussions that included the concerns from the comments summarized previously in this section, the CAC/HP ECS Working Group members weighed in on appropriate minimum external static pressure requirements. (CAC ECS: CAC/HP ECS Working Group meeting, No. 86 at pp. 31-128) Recommendation #2 of the CAC/HP ECS Working Group Term Sheet states that the minimum required external static pressure for CAC/HP blower coil systems other than mobile home systems, ceiling-mount and wall-mount systems, low and mid-static multi-split systems, space constrained systems, and small-duct, high-velocity systems should be 0.50 in. wc. for all capacities. (CAC ECS: ASRAC Term Sheet, No. 76 at p. 2) In comments in response to the November 2015 SNOPR, Unico supported the values discussed during the ASRAC meetings. (CAC TP: Unico, No. 63 at p. 12) JCI and Carrier commented that this topic has already been resolved through the ASRAC meetings.

13

(CAC TP: JCI, No. 66 at p. 21; Carrier, No. 62 at p. 20)

13

The comment period for the November 2015 SNOPR was still open during the CAC/HP ECS Working Group negotiations.

Based on DOE's analysis and consistent with the CAC/HP ECS Working Group Term Sheet, DOE proposes to adopt, for inclusion into 10 CFR part 430, subpart B, appendix M1, for systems other than mobile home, ceiling-mount and wall-mount systems, low and mid-static multi-split systems, space-constrained systems, and small-duct, high-velocity systems, a minimum external static pressure requirement of 0.50 in. wc. DOE is aware that such changes will impact the certification ratings for SEER, HSPF, and EER and is addressing such impact in the current energy conservation standards rulemaking.

14

For this reason, DOE is not proposing to make this change in appendix M.

14

Docket No. EERE-2014-BT-STD-0048.

b. Non-Conventional Central Air Conditioners and Heat Pumps

In response to the November 2015 SNOPR and during the CAC/HP ECS Working Group negotiations, DOE also received comment regarding the minimum external static pressure requirements for mobile home systems, ceiling-mount and wall-mount systems, low and mid-static multi-split systems, space-constrained systems, and small-duct, high-velocity systems. In its comments, First Co. proposed to reduce the minimum static pressure for space-constrained and multi-family blower coils to 0.25 in. wc. or lower. (CAC TP: First Co., No. 56 at p. 2) The CAC/HP ECS Working Group included in its Final Term Sheet Recommendation #2, which is summarized in Table III.4 below. (CAC ECS: ASRAC Term Sheet, No. 76 at p. 2)

Table III.4—CAC/HP ECS Working Group Recommended Minimum External Static Pressure Requirement

Product description

Minimum

external static pressure

(in. wc.)

All central air conditioners and heat pumps except (2)-(7) below

0.50.

(2) Ceiling-mount and Wall-mount Blower Coil System

TBD by DOE.

(3) Manufactured Housing Air Conditioner Coil System

0.30.

(4) Low-Static System

0.10.

(5) Mid-Static System

0.30.

(6) Small Duct, High Velocity System

1.15.

(7) Space Constrained

0.30.

Recommendation #1 of the CAC/HP ECS Working Group included suggested definitions for distinguishing the CAC/HP varieties included in Recommendation #2 (Table III.4) to enable the proper administration of the CAC/HP ECS Working Group's recommended minimum external static pressure requirements. Recommendation #1 stated:

• Suggested definitions capture the intent of the Working Group and DOE should adopt them as is or modify them in a manner that captures the same intent.

• For those definitions that contain a maximum external static pressure requirement, the unit's maximum external static pressure would be determined using a dry coil test without electric heat installed and without an air filter installed at the unit's certified airflow, or, if the airflow is not certified, at an airflow of 400 cfm per ton of certified capacity.

• For those condensing units distributed in commerce with different indoor unit combinations, each specific combination would need to meet the applicable definition in order to be rated with the associated static.

The CAC/HP ECS Working Group's recommended definitions are as follows:

• A ceiling-mount blower coil system is a split-system central air conditioner or heat pump that contains a condensing unit and an indoor unit intended to be exclusively installed by being secured to the ceiling of the conditioned space, with return air directly to the bottom of the unit (without ductwork), having an installed height no more than 12 inches (not including condensate drain lines) and depth (in the direction of airflow) of no more than 30 inches, with supply air discharged horizontally. The certified cooling capacity must be less than or equal to 36,000 Btu/h.

• A wall-mount blower coil system is a split-system central air conditioner or heat pump that contains a condensing unit and an indoor unit intended to be exclusively installed by having the back side of the unit secured to the wall within the conditioned space, with capability of front air return (without ductwork) and not capable of horizontal airflow, having a height no more than 45 inches, a depth of no more than 22 inches (including tubing connections), and a width no more than 24 inches. The certified cooling capacity must be less than or equal to 36,000 Btu/h.

• Manufactured housing air conditioner coil system is a split-system air conditioner or heat pump that contains a condensing unit with an indoor unit that: (1) Is distributed in commerce for installation only in a manufactured home with the home and equipment complying with HUD Manufactured Home Construction Safety Standard 24 CFR part 3280; (2) has an external static pressure that must not exceed 0.4 inches of water; and (3) has an indoor unit that must bear a label in at least

1/4

inch font that reads “For installation only in HUD Manufactured Home per Construction Safety Standard 24 CFR part 3280.” Note, manufacturers must certify which combinations are manufactured housing air conditioner coil system.

• Low-static system means a ducted multi-split or multi-head mini-split system where all indoor sections produce greater than 0.01 and a maximum of 0.35 inches of water of external static pressure when operated at the full-load air volume rate not exceeding 400 cfm per rated ton of cooling.

• Mid-static system means a ducted multi-split or multi-head mini-split system where all indoor sections produce greater than 0.20 and a maximum of 0.65 inches of water of external static pressure when operated at the full-load air volume rate not exceeding 400 cfm per rated ton of cooling.

UTC/Carrier supported the low and medium static definitions as presented during the CAC/HP ECS Working Group meetings, in place of the short-duct unit definition DOE proposed in the November 2015 SNOPR. (CAC TP: UTC/Carrier, No. 62 at p. 3-4,19) AHRI and Mitsubishi recommended in their comments nearly identical definitions to those recommended in the CAC/HP ECS Working Group term sheet. (CAC TP: AHRI, No. 70 at p. 17; Mitsubishi, No. 68 at p. 2-3) Goodman generally supported the comments made by industry during the initial meetings of the CAC/HP ECS Working Group, in which additional sub‐categories of “short-ducted” systems were proposed. Goodman recommended that DOE only include CAC/HP ECS Working Group's definitions and modifications to the test procedure in the “M1” test procedure and not part of “M” test procedure because the proposed modification to the test procedure would increase the measured energy consumption for those “short-ducted” systems being marketed under the current “M” test procedure. (CAC TP: Goodman, No. 73 at p. 6-7)

DOE agrees with the intent of Recommendation #1 and #2 of the CAC/HP ECS Working Group Term Sheet. DOE recognizes that the CAC/HP varieties included in these recommendations have unique installation characteristics that result in different field external static pressure conditions, and in turn, indoor fan power consumption in the field. While conventional split systems are typically installed in attics or basements and require long ductwork to deliver conditioned air to the conditioned space, ceiling-mount systems, wall-mount systems, space-constrained systems, low-static systems and mid-static systems are installed in or in closer proximity to the spaces they condition, typically requiring shorter ductwork than conventional split systems. The field external static pressure for these non-conventional systems is lower than the external static pressure for conventional split systems as a result. In this SNOPR, DOE proposes to adopt the CAC/HP ECS Working Group recommended minimum external static pressure requirements for space-constrained systems, low-static systems, and mid-static systems to be more reflective of field conditions for these reasons, with one modification. DOE understands that when some space-constrained outdoor units are paired with conventional indoor units, the minimum external static pressure requirement for space constrained systems recommended by the CAC/HP ECS Working Group, 0.30 in. wc., would not be appropriate for these installations. Therefore, DOE also proposes to limit the CAC/HP ECS Working Group recommended minimum external static pressure requirement for space-constrained systems only to space-constrained indoor units and single-package space-constrained units.

The CAC/HP ECS Working Group tasked DOE with the determination of the appropriate minimum external static pressure for ceiling-mount and wall-mount systems. During the CAC/HP ECS Working Group meetings, manufacturers of these systems suggested a minimum external static pressure requirement of 0.30 in. wc. (CAC ECS: CAC/HP ECS Working Group meeting, No. 88 at p. 31) However, the CAC/HP ECS Working Group did not adopt this as a recommendation primarily due to lack of time to thoroughly review the subject. DOE proposes to specify a minimum external static pressure requirement of 0.30 in. wc. for ceiling-mount and wall-mount systems, consistent with manufacturers' recommendations.

Mobile home

15

systems also have lower field external static pressure than conventional split systems. Mobile home systems are installed in homes that meet the HUD Manufactured Home Construction Safety Standard 24 CFR part 3280, which includes a maximum threshold of 0.30 in. wc. for the restrictiveness of ductwork. Consistent with these HUD requirements, the CAC/HP ECS Working Group recommendation, and the external static pressure requirements for mobile home systems in the DOE furnace fan test procedure, DOE proposes to adopt 0.30 in. wc. as the minimum external static pressure required for testing mobile home central air conditioning and heat pump systems.

15

In previous rulemaking documents for the furnace fan test procedure and, DOE used the term “manufactured home” to be synonymous with “mobile home,” as used in some definitions in the

Federal Register

. 10 CFR 430.2. DOE will use the term “mobile home” in place of “manufactured home” hereinafter to be consistent with the

Federal Register

definitions that use “mobile home”, such as for “mobile home furnace.” All provisions and statements regarding mobile homes and mobile home products are applicable to manufactured homes and manufactured home products.

In this SNOPR, DOE proposes to adopt the CAC/HP ECS Working Group recommendations for minimum external static pressure requirements for low-static and mid-static systems. By the definitions recommended by the Working Group, these systems are not capable of producing external static pressure significantly higher than the recommended minimum external static

pressure requirements. Consequently, DOE expects that any system that would meet these definitions would be incapable of properly conditioning a home that has ductwork with an external static pressure significantly higher than the proposed minimum.

The CAC/HP ECS Working Group did not recommend a change to the current minimum external static pressure required (1.15 in. wc.) for SDHV systems with a cooling or heating capacity between 29,000 to 42,500Btu/h. However, the CAC/HP ECS Working Group recommended that 1.15 in. wc. also be used as the minimum external static pressure requirement for SDHV systems of all other capacities. Using a single minimum external static pressure value for all capacities of a given CAC/HP variety is consistent with the approach recommended by the Working Group for all CAC/HP varieties. DOE proposes to adopt the Working Group recommendation for the minimum external static pressure requirement for SDHV systems.

Table III.5 summarizes DOE's proposed minimum external static pressure requirements.

Table III.5—Proposed Minimum External Static Pressure Requirements

CAC/HP Variety

Minimum

external static pressure

(in. wc.)

Conventional (

i.e.,

all central air conditioners and heat pumps not otherwise listed in this table)

0.50

Ceiling-mount and Wall-mount

0.30

Mobile Home

0.30

Low-Static

0.10

Mid-Static

0.30

Small Duct, High Velocity

1.15

Space-Constrained (indoor and single-package units only)

0.30

Issue 15:

DOE requests comments on the proposed minimum external static pressure requirements.

DOE also agrees with the intent of the definitions recommended by the CAC/HP ECS Working Group. DOE proposes to adopt those definitions with minor modifications to make them consistent with other proposed regulatory language. For example, DOE is proposing to replace the term “condensing unit” in the CAC/HP ECS Working Group recommended definition for mobile home systems with the term “outdoor unit” to ensure that the definition applies to both mobile home air conditioners and heat pumps. DOE proposes to adopt the following definitions for the CAC/HP varieties included in Recommendations #1 and #2 in the CAC/HP ECS Working Group Term Sheet:

•

Ceiling-mount blower coil system

means a split system for which the outdoor unit has a certified cooling capacity less than or equal to 36,000 Btu/h and the indoor unit is shipped with manufacturer-supplied installation instructions that specify to secure the indoor unit only to the ceiling of the conditioned space, with return air directly to the bottom of the unit (without ductwork), having an installed height no more than 12 inches (not including condensate drain lines) and depth (in the direction of airflow) of no more than 30 inches, with supply air discharged horizontally.

•

Low-static blower coil system

means a ducted multi-split or multi-head mini-split system for which all indoor units produce greater than 0.01 in. wc. and a maximum of 0.35 in. wc. external static pressure when operated at the cooling full-load air volume rate not exceeding 400 cfm per rated ton of cooling.

•

Mid-static blower coil system

means a ducted multi-split or multi-head mini-split system for which all indoor units produce greater than 0.20 in. wc. and a maximum of 0.65 in. wc. when operated at the cooling full-load air volume rate not exceeding 400 cfm per rated ton of cooling.

•

Mobile home blower coil system

means a split system that contains an outdoor unit and an indoor unit that meet the following criteria: (1) Both the indoor and outdoor unit are shipped with manufacturer-supplied installation instructions that specify installation only in a mobile home with the home and equipment complying with HUD Manufactured Home Construction Safety Standard 24 CFR part 3280; (2) the indoor unit cannot exceed 0.40 in. wc. when operated at the cooling full-load air volume rate not exceeding 400 cfm per rated ton of cooling; and (3) the indoor unit and outdoor unit each must bear a label in at least

1/4

inch font that reads “For installation only in HUD manufactured home per Construction Safety Standard 24 CFR part 3280.”

•

Wall-mount blower coil system

means a split system for which the outdoor unit has a certified cooling capacity less than or equal to 36,000 Btu/h and the indoor unit is shipped with manufacturer-supplied installation instructions that specify to secure the back side of the unit only to a wall within the conditioned space, with the capability of front air return (without ductwork) and not capable of horizontal airflow, having a height no more than 45 inches, a depth of no more than 22 inches (including tubing connections), and a width no more than 24 inches (in the direction parallel to the wall).

c. Certification Requirements

DOE proposes to establish the certification requirements for Appendix M1 to require manufacturers to certify the kind(s) of CAC/HP associated with the minimum external static pressure used in testing or rating (

i.e.,

ceiling-mount, wall-mount, mobile home, low-static, mid-static, small duct high velocity, space constrained, or conventional/not otherwise listed). In the case of mix-match ratings for multi-split, multi-head mini-split, and multi-circuit systems, manufacturers may select two kinds. In addition, models of outdoor units for which some combinations distributed in commerce meet the definition for ceiling-mount and wall-mount blower coil system are still required to have at least one coil-only rating (which uses the 441W/1000 scfm default fan power value) that is representative of the least efficient coil distributed in commerce with the particular model of outdoor unit. Mobile home systems are also required to have at least one coil-only rating that is representative of the least efficient coil distributed in commerce with the particular model of outdoor unit. DOE proposes to specify a default fan power value of 406W/1000 scfm, rather than 441W/1000 scfm, for mobile home coil-only systems. Details of this proposal are discussed in detail in section III.C.2.

Issue 16:

DOE requests comment on the proposed definitions for kinds of CAC/HP associated with administering minimum external static pressure requirements.

d. External Static Pressure Reduction Related to Condensing Furnaces

In the November 2015 SNOPR, DOE requested comment on its proposal to implement a 0.10 in. wc. reduction in the minimum external static pressure requirement for air conditioning units tested in blower coil (or single-package) configuration in which a condensing furnace is in the airflow path during the test. This issue was also discussed as part of the CAC/HP ECS Working Group negotiation process. ADP, Lennox, NEEA, NPCC, California IOUs, Rheem, ACEEE, NRDC, and ASAP did not support the proposal because it would make the ratings for units paired with condensing furnaces less reflective of field energy use. (CAC TP: ADP, No. 59 at p. 12; Lennox, No. 61 at p. 20; NEEA and NPCC, No. 64 at p. 8; California IOUs, No. 67 at p. 6; Rheem, No. 69 at p. 17; ACEEE, NRDC, ASAP, No. 72 at

p. 4) JCI commented that this topic has already be resolved through the CAC/HP ECS Working Group meetings. (CAC TP: JCI, No. 66 at p. 21) Carrier commented to refer to the agreement on external static pressure from the CAC/HP ECS Working Group and expressed the view that this credit is contrary to better aligning the rating procedure with real world data. (CAC TP: Carrier, No. 62 at p. 21) As Carrier and JCI point out, Recommendation #2 of the CAC/HP ECS Working Group Term Sheet also states that the proposed reduction in minimum external static pressure required for units paired with condensing furnaces should not be used. (CAC ECS: CAC/HP ECS Working Group Term Sheet, No. 76 at p. 2)

In light of public comments and the consensus of the CAC/HP ECS Working Group, DOE is not proposing to adopt a reduced minimum external static pressure requirement for air conditioning units tested in blower coil (or single-package) configuration in which a condensing furnace is in the airflow path during the test.

Issue 17:

DOE requests comments on not including a reduced minimum external static pressure requirement for blower coil or single-package systems tested with a condensing furnace.

2. Default Fan Power for Rating Coil-Only Units

The default fan power value (hereafter referred to as “the default value”) is used to represent fan power input when testing coil-only air conditioners, which do not include their own fans.

16

In the current test procedure, the default value is 365 Watts (W) per 1,000 cubic feet per minute of standard air (scfm) and there is an associated adjustment to measured capacity to account for the fan heat equal to 1,250 British Thermal Units per hour (Btu/h) per 1,000 scfm (10 CFR part 430, subpart B, Appendix M, section 3.3.d). The default value was discussed in the June 2010 NOPR, in which DOE did not propose to revise it due to uncertainty on whether higher default values would better represent field installations. 75 FR 31227 (June 2, 2010). In response to the June 2010 NOPR, Earthjustice commented that the existing default values for coil-only units in the DOE test procedure were not supported by substantial evidence. Earthjustice stated that external static pressures measured from field data showed significantly higher values than DOE's default values in its existing test procedure. (CAC TP: Earthjustice, No. 15 at p. 2) In the November 2015 SNOPR, DOE proposed to update the default value to be more representative of field conditions (

i.e.,

consistent with indoor fan power consumption at the minimum required external static pressures proposed in the November 2015 SNOPR). In the November 2015 SNOPR, DOE used indoor fan electrical power consumption data from product literature, testing, and exchanges with manufacturers collected for the furnace fan rulemaking (79 FR 506, January 3, 2014) to determine an appropriate default value for coil-only products.

17

(80 FR 69318)

16

See 10 CFR part 430, subpart B, appendix M, section 3.3.d.

17

For a complete explanation of DOE's methodology, see 80 FR 69278, 69319-20 (Nov. 9, 2015).

DOE calculated the adjusted default fan power to be 441 W/1000 scfm. In the November 2015 SNOPR, DOE proposed to use this value in Appendix M1 of 10 CFR part 430 subpart B where Appendix M included a default fan power of 365 W/1000 scfm. DOE proposed not to make such replacements in Appendix M of 10 CFR part 430 subpart B.

In response to the November 2015 SNOPR, NEEA, NPCC, ACEEE, NRDC, ASAP, and the California IOUs supported raising the coil-only test default fan power to 441 W/1000 scfm to allow for more representative ratings of units. (CAC TP: NEEA and NPCC, No. 64 at p. 8; ACEEE, NRDC, ASAP, No. 72 at p. 4; California IOUs, No. 67 at p. 2) ACEEE, NRDC, and ASAP also commented that they would be happy with 440 W/1000 scfm, as the implied precision of using 441W/1000 scfm is artificial. (CAC TP: ACEEE, NRDC, ASAP, No. 72 at p. 4)

The CAC/HP ECS Working Group also discussed the default value as part of the negotiation process. Ultimately, the Working Group came to a consensus on a recommendation for the default value. Recommendation #3 of the CAC/HP ECS Working Group Term Sheet states that the default fan power for rating the performance of all coil-only systems other than manufactured housing products shall be 441W/1000 scfm. (CAC ECS: ASRAC Working Group Term Sheet, No. 76 at p. 3)

Consistent with the CAC/HP ECS Working Group Term Sheet, DOE maintains its previous proposal to use a default value of 441 W/1000 scfm for split-system air conditioner, coil-only tests. DOE proposes to use this value in appendix M1 of 10 CFR part 430 subpart B in place of the default fan power of 365 W/1000 scfm that has been used previously in Appendix M.

Recommendation #3 of the CAC/HP ECS Working Group Term Sheet also stated that DOE should calculate an alternative default fan power for rating mobile home air conditioner coil-only units based on the minimum external static pressure requirement for blower coil mobile home units (0.30 in. wc.) that it suggested in recommendation #2 of the Term Sheet. (CAC TP: ASRAC Working Group Term Sheet, No. 76 at p. 3) As discussed in section III.C.1, the CAC/HP ECS Working Group included this recommendation because HUD requires less restrictive ductwork for mobile homes than for other types of housing, which reduces electrical energy consumption of the indoor fan. The default value used to rate coil-only mobile home systems should reflect this difference in field energy consumption to improve the field representativeness of the test procedure.

DOE agrees with the CAC/HP ECS Working Group's recommendation to use a different default value for coil-only mobile home systems to reflect the difference in ductwork and, in turn, external static pressure of field installations of these systems. In this SNOPR, DOE used the same aforementioned furnace fan power consumption data and methodology to calculate the appropriate default value for mobile home fan power consumption. However, in this case, DOE evaluated furnace fan power consumption at 0.54 in. wc., which is the 0.30 in. wc. recommended by the CAC/HP ECS Working Group plus 0.24 in. wc. to account for filter and indoor coil pressure drop. The resulting average indoor fan power consumption at the external static pressure representative of mobile home systems is 8% lower than the average indoor fan power consumption at the external static pressure representative of conventional systems. Applying the 8% reduction to the 441W/1000 scfm representing conventional indoor fan power consumption yields 406 W/1000 scfm. Thus, DOE proposes to use 406 W/1000 scfm as the default value for mobile home systems.

DOE notes that it used data from all of the furnaces in its database to calculate this value, instead of only mobile home furnaces, because its database includes a small number of mobile home furnaces that do not represent all capacities or motor technologies. DOE recognizes that including non-mobile home furnaces in this analysis may bias the result. Due to the space constraints typical of mobile home system installations, mobile home indoor units generally have more restrictive cabinets compared to conventional indoor units, which would be expected to increase the static pressure experienced by the indoor fan

and, in turn, increase indoor fan power consumption. Consequently, DOE expects that a default value calculated based on mobile home indoor fan performance data may result in a higher default value for these systems than the value proposed. In addition to the new default power values, DOE proposes to adjust measured capacity to account for the fan heat consistent with 441W/1000 scfm and 406 W/1000 scfm: 1,505 and 1,385 Btu/h per 1,000 scfm.

Issue 18:

DOE requests comment on the proposed default fan power value for coil-only mobile home systems. DOE also requests mobile home indoor fan performance data for units of all capacities and that use all available motor technologies in order to allow confirmation that the proposed default value is a good representation for mobile home units.

The DOE test procedure needs a definition for a mobile home coil-only unit to appropriately apply the proposed default value for these kinds of CAC/HP. DOE proposes to define mobile home coil-only unit as:

•

Mobile home coil-only system

means a coil-only split system that includes an outdoor unit and coil-only indoor unit and coil-only indoor unit that meet the following criteria: (1) The outdoor unit is shipped with manufacturer-supplied installation instructions that specify installation only for mobile homes that comply with HUD Manufactured Home Construction Safety Standard 24 CFR part 3280, (2) the coil-only indoor unit is shipped with manufacturer-supplied installation instructions that specify installation only in a mobile home furnace, modular blower, or designated air mover that complies with HUD Manufactured Home Construction Safety Standard 24 CFR part 3280, and (3) the coil-only indoor unit and outdoor unit each has a label in at least

1/4

inch font that reads “For installation only in HUD manufactured home per Construction Safety Standard 24 CFR part 3280.”

Issue 19:

DOE requests comments on its proposed definition for mobile home coil-only unit.

3. Revised Heating Load Line Equation

a. General Description of Heating Season Performance Factor (HSPF)

In the current test procedure, the HSPF determined for heat pumps in heating mode is calculated by evaluating the energy usage of both the heat pump unit (reverse refrigeration cycle) and the resistive heat component when matching the house heating load for the range of outdoor temperatures representing the heating season. The temperature range is split into 5-degree “bins”, and an average temperature and total number of hours are assigned to each bin, based on weather data used to represent the heating season for each climate region. An HSPF value can be calculated for each climate region, but the HSPF rating is based on Region IV. In the HSPF calculation, the amount of heating delivered is set equal to the heating load, which increases as the bin temperature decreases. In the current test procedure, the heating load is proportional to the difference between 65 °F and the outdoor (bin) temperature. The heating load also is dependent on the size of the house that the unit heats. For the HSPF calculation the size of the house is set based on the capacity of the heat pump. For the current test procedure, the heating load is proportional to the heating capacity of the heat pump when operating at 47 °F outdoor temperature. The resulting relationship between heating load and outdoor temperature is called the heating load line equation—it slopes downward from low temperatures, dropping to zero at 65 °F. The slope of the heating load line equation affects HSPF both by dictating the heat pump capacity level used by two stage or variable speed heat pumps at a given outdoor temperature, and also by changing the amount of auxiliary electric resistance heat required when the unit's heat pumping capacity is lower than the heating load. The current test procedure defines two heating load levels, called the minimum heating load line and maximum heating load line. However, it is the minimum heating load line in Region IV that is used to determine HSPF for rating purposes.

18

18

See 10 CFR part 430, subpart B, appendix M, Section 1. Definitions.

b. HSPF Issues

Studies have indicated that the current HSPF test and calculation procedure overestimates ratings because the current minimum heating load line equation is too low compared to real world situations.

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In response to the November 2014 ECS RFI, NEEA and NPCC commented that the federal test procedure does a poor job representing balance point temperatures and electric heat energy use in the case of heat pump systems. They pointed out the inability of the test procedure to capture dynamic response to heating needs, such as the use of electric resistance (strip) heat during morning or afternoon temperature setup (

i.e.,

rewarming of the space after a thermostat setback period). They also expressed concerns about capturing the use of electric resistance heat during defrost cycles and at times when it shouldn't be needed, such as when outdoor temperatures are above 30 ºF. (CAC ECS: NEEA & NPCC, No. 19 at p. 2)

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Erbs, D.G., C.E. Bullock, and R.J. Voorhis, 1986. “New Testing and Rating Procedures for Seasonal Performance of Heat Pumps with Variable speed Compressors”, ASHRAE Transactions, Volume 92, Part 2B.

Francisco, Paul W., Larry Palmiter, and David Baylon, 2004. “Understanding Heating Seasonal Performance Factors for Heat Pumps”, 2004 Proceedings of the ACEEE Summer Study on Energy Efficiency in Buildings.

Fairey, Philip, Danny S. Parker, Bruce Wilcox, and Matthew Lombardi, 2004. “Climatic Impacts on Seasonal Heating Performance Factor (HSPF) and Seasonal Energy Efficiency Ratio (SEER) for Air-Source Heat Pumps”, ASHRAE Transactions, Volume 110, Part 2.

DOE agreed with the NEEA and NPCC regarding balance point in the November 2015 SNOPR and noted that the heating balance point determined for a typical heat pump using the current minimum heating load line equation in Region IV is near 17 °F, while the typical balance point is in the range 26 to 32 °F, resulting from installing a proper-sized unit based on the design cooling load according to ACCA Manual S, 2014.

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The low heating balance point means that the test procedure calculation adds in much less auxiliary heat than would actually be needed in cooler temperatures, thus inflating the calculated HSPF. Furthermore, the zero load point of 65 °F ambient, which is higher than the typical 50-60 °F zero load point,

21

causes the test procedure calculation to include more hours of operation at warmer outdoor temperatures, for which heat pump operation requires less energy input, again inflating the calculated HSPF. These effects result in overestimation of rated HSPF up to 30% compared to field performance, according to a paper by the Florida Solar Energy Center (FSEC).

22

For these reasons, DOE reviewed the choice of heating load line equation for HSPF ratings and proposed to modify it in the November 2015 SNOPR. 80 FR at 69320-2 (Nov. 9, 2015).

20

Manual S: Residential Equipment Selection

(2nd ed., Ver. 1.00). (2014). Arlington, VA: Air Conditioning Contractors of America (ACCA). pp. N7-N1.

21

Francisco, Paul W., Larry Palmiter, and David Baylon, 2004. “Understanding Heating Seasonal Performance Factors for Heat Pumps”, 2004 Proceedings of the ACEEE Summer Study on Energy Efficiency in Buildings.

22

Fairey, Philip, Danny S. Parker, Bruce Wilcox, and Matthew Lombardi, 2004. “Climatic Impacts on Seasonal Heating Performance Factor (HSPF) and Seasonal Energy Efficiency Ratio (SEER) for Air-Source Heat Pumps”, ASHRAE Transactions, Volume 110, Part 2.

As part of its review for the November 2015 SNOPR, DOE considered a 2015

Oak Ridge National Laboratory (ORNL) study

23

that examined the heating load line equation for cities representing the six climate regions of the HSPF test procedure in Appendix M. The study developed modified regional heating load line equations, including a heating load line equation for Region IV for calculation of a unit's HSPF. ORNL conducted building load analyses using the EnergyPlus simulation tool (see energyplus.net) using single-family Prototype Residential House models based on building characteristics specified by the 2006 International Energy Conservation Code (2006 IECC). The study concluded that a heating load line equation closer to the maximum load line equation of the current test procedure and with a lower zero-load ambient temperature would better represent field operation than the minimum load line equation presently used for HSPF rating values.

23

ORNL, Rice, C. Keith, Bo Shen, and Som S. Shrestha, 2015.

An Analysis of Representative Heating Load Lines for Residential HSPF Ratings,

ORNL/TM-2015/281, July. (Docket No. EERE-2009-BT-TP-0004-0046).

c. November 2015 SNOPR Heating Load Line Equation Proposal

In the November 2015 SNOPR, DOE proposed a new heating load line equation based on the findings of the ORNL study:

EP24AU16.002

T

j

= the outdoor bin temperature, °F

T

zl

= the zero-load temperature, °F

T

OD

= the outdoor design temperature, °F, which varies by climate region

C = the slope (adjustment) factor

Q

c

(95 °F) = the nominal cooling capacity at 95 °F, Btu/h

The proposed equation included the following changes from the current heating load line equation used for the HSPF calculation:

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24

In the current test procedure, for all climate regions but

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