Energy Conservation Program: Test Procedure for Consumer Boilers

Federal RegisterMar 13, 2023

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DEPARTMENT OF ENERGY

10 CFR Parts 429 and 430

[EERE-2019-BT-TP-0037]

RIN 1904-AE83

Energy Conservation Program: Test Procedure for Consumer Boilers

AGENCY:

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

ACTION:

Final rule.

SUMMARY:

The U.S. Department of Energy (“DOE”) amends its test procedure for consumer boilers established under the Energy Policy and Conservation Act. This rulemaking fulfills DOE's obligation to review its test procedures for covered products at least once every seven years. The revisions include: incorporating by reference the latest versions of the industry standards currently referenced in the Federal test procedure; relocating the test procedure to a new appendix separate from the residential furnace test procedure; removing an extraneous definition from its regulatory definitions; and making clarifying corrections to calculations. These revisions will improve the representativeness of the test method and will not be unduly burdensome to conduct.

DATES:

The effective date of this rule is April 12, 2023. The amendments will be mandatory for product testing starting September 11, 2023.

The incorporation by reference of certain material listed in the rule is approved by the Director of the Federal Register as of April 12, 2023. The incorporation by reference of certain other material listed in the rule was approved by the Director of the Federal Register on March 23, 2009, and February 16, 2016.

ADDRESSES:

The docket, which includes

Federal Register

notices, public meeting attendee lists and transcripts, 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, not all documents listed in the index may be publicly available, such as those containing information that is exempt from public disclosure.

A link to the docket web page can be found at

www.regulations.gov/docket/EERE-2019-BT-TP-0037.

The docket web page contains instructions on how to access all documents, including public comments, in the docket.

For further information on how to review the docket, contact the Appliance and Equipment Standards Program staff at (202) 287-1445 or by email:

ApplianceStandardsQuestions@ee.doe.gov.

FOR FURTHER INFORMATION CONTACT:

Ms. Julia Hegarty, U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Office, EE-2J, 1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: (240) 597-6737. Email:

ApplianceStandards Questions@ee.doe.gov.

Ms. Amelia Whiting, U.S. Department of Energy, Office of the General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: (202) 586-2588. Email:

Amelia.Whiting@hq.doe.gov.

SUPPLEMENTARY INFORMATION:

DOE maintains material previously approved for incorporation by reference in part 430: ANSI/ASHRAE 103-1993 and ASTM D2156-09 (Reapproved 2013). DOE incorporates by reference the following industry standards into 10 CFR part 430:

ANSI/ASHRAE Standard 41.6-2014, “Standard Method for Humidity Measurement,” ANSI-approved July 3, 2014 (“ASHRAE 41.6-2014”).

ANSI/ASHRAE 103-2017, “Method of Testing for Annual Fuel Utilization Efficiency of Residential Central Furnaces and Boilers,” ANSI-approved July 3, 2017 (“ASHRAE 103-2017”).

Copies ofANSI/ASHRAE 41.6-2014 and ANSI/ASHRAE 103-2017 can be obtained from the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE), 180 Technology Parkway NW, Peachtree Corners, GA 30092, (800) 527-4723 or (404) 636-8400, or online at

www.ashrae.org.

ASTM International (“ASTM”) Standard D2156-09 (Reapproved 2018), “Standard Test Method for Smoke Density in Flue Gases from Burning Distillate Fuels,”approved October 1, 2018 (“ASTM D2156-09 (R2018)”).

Copies of ASTM D2156-09 (R2018) can be obtained from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959 or online at

www.astm.org.

International Electrotechnical Commission (“IEC”) 62301, “Household electrical appliances—Measurement of standby power,” (Edition 2.0) 2011-01 (“IEC 62301”).

Copies of IEC 62301 can be obtained from the International Electrotechnical Commission (“IEC”), 3 Rue de Varembe, Case Postale 131, 1211 Geneva 20, Switzerland; or online at

webstore.iec.ch.

See section IV.N of this document for a further discussion of these standards.

Table of Contents

I. Authority and Background

A. Authority

B. Background

II. Synopsis of the Final Rule

III. Discussion

A. Scope of Applicability

1. Combination Space/Water Heating Boilers

2. Heat Pump Boilers

B. Definitions

C. Metric

D. Updates to Industry Standards

1. ANSI/ASHRAE 103

2. IEC 62301 and ASTM D2156-09

E. Steady-State Efficiency for Condensing Modulating Boilers

F. Corrections and Clarifications

1. Off-Cycle Losses

2. Conversion Factor for British Thermal Units

3. Oil Pressure Instrumentation Error

4. Gas Inlet Conditions

5. Active Mode Electrical Energy Consumption

6. Circulator Pumps

7. Units With Draft Hoods or Draft Diverters

8. Rounding of AFUE

G. Other Test Procedure Topics

1. Outdoor Design Temperature

2. Ambient Conditions

3. Combustion Settings

4. Supplemental Test Instructions

5. Input Rates for Step Modulating Boilers

6. Return Water Temperature

7. Standby Mode and Off Mode Electrical Energy Consumption

8. Full Fuel Cycle Efficiency

9. Idle Losses

H. Alternative Efficiency Determination Methods

I. Certification Provisions for Cast-Iron Boilers

J. Effective and Compliance Dates

K. Test Procedure Costs

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Orders 12866 and 13563

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. Congressional Notification

N. Description of Materials Incorporated by Reference

V. Approval of the Office of the Secretary

I. Authority and Background

Furnaces, which include consumer boilers, are included in the list of “covered products” for which the U.S. Department of Energy (“DOE”) is authorized to establish and amend energy conservation standards and test procedures. (42 U.S.C. 6291(23); 42 U.S.C. 6292(a)(5)) DOE's energy conservation standards and test procedures for consumer boilers are currently prescribed at 10 CFR 430.32(e)(2) and 10 CFR part 430, subpart B, appendix N,

Uniform Test Method for Measuring the Energy Consumption of Furnaces and Boilers

(“appendix N”), respectively.

The following sections discuss DOE's authority to establish test procedures for consumer boilers and relevant background information regarding DOE's consideration of test procedures for this product.

Upon the effective date of this final rule, the test procedure for consumer boilers will be relocated to 10 CFR 430, subpart B, appendix EE.

A. Authority

The Energy Policy and Conservation Act, Public Law 94-163, as amended (“EPCA”),

authorizes DOE to regulate the energy efficiency of a number of consumer products and certain industrial equipment. (42 U.S.C. 6291-6317) Title III, Part B of EPCA

established the Energy Conservation Program for Consumer Products Other Than Automobiles, which sets forth a variety of provisions designed to improve energy efficiency. These products include furnaces, which include consumer boilers, the subject of this document. (42 U.S.C. 6292(a)(5))

All references to EPCA in this document refer to the statute as amended through the Energy Act of 2020, Public Law 116-260 (Dec. 27, 2020), which reflect the last statutory amendments that impact Parts A and A-1 of EPCA.

For editorial reasons, upon codification in the U.S. Code, Part B was redesignated Part A.

The energy conservation program under EPCA consists essentially of four parts: (1) testing, (2) labeling, (3) Federal energy conservation standards, and (4) certification and enforcement procedures. Relevant provisions of EPCA specifically include definitions (42 U.S.C. 6291), test procedures (42 U.S.C. 6293), labeling provisions (42 U.S.C. 6294), energy conservation standards (42 U.S.C. 6295), and the authority to require information and reports from manufacturers (42 U.S.C. 6296).

The testing requirements consist of test procedures that manufacturers of covered products must use as the basis for (1) certifying to DOE that their products comply with the applicable energy conservation standards adopted under EPCA (42 U.S.C. 6295(s)), and (2) making other representations about the efficiency of those products (42 U.S.C. 6293(c)). Similarly, DOE must use these test procedures to determine whether the products comply with any relevant standards promulgated under EPCA. (42 U.S.C. 6295(s))

Federal energy efficiency requirements for covered products established under EPCA generally supersede State laws and regulations concerning energy conservation testing, labeling, and standards. (42 U.S.C. 6297) DOE may, however, grant waivers of Federal preemption for particular State laws or regulations, in accordance with the procedures and other provisions of EPCA. (42 U.S.C. 6297(d))

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

EPCA also requires that, at least once every 7 years, DOE evaluate test procedures for each type of covered product, including consumer boilers, to determine whether amended test procedures would more accurately or fully comply with the requirements for the test procedures to not be unduly burdensome to conduct and be reasonably designed to produce test results that reflect energy efficiency, energy use, and estimated operating costs during a representative average use cycle or period of use. (42 U.S.C. 6293(b)(1)(A))

If the Secretary determines, on her own behalf or in response to a petition by any interested person, that a test procedure should be prescribed or amended, the Secretary shall promptly publish in the

Federal Register

proposed test procedures and afford interested persons an opportunity to present oral and written data, views, and arguments with respect to such procedures. The comment period on a proposed rule to amend a test procedure shall be at least 60 days and may not exceed 270 days. In prescribing or amending a test procedure, the Secretary shall take into account such information as the Secretary determines relevant to such procedure, including technological developments relating to energy use or energy efficiency of the type (or class) of covered products involved. (42 U.S.C. 6293(b)(2)) If DOE determines that test procedure revisions are not appropriate, DOE must publish its determination not to amend the test procedures.

In addition, EPCA requires that DOE amend its test procedures for all covered products to integrate measures of standby mode and off mode energy consumption into the overall energy efficiency, energy consumption, or other energy descriptor, unless the current test procedure already incorporates the standby mode and off mode energy consumption, or if such integration is technically infeasible. (42 U.S.C. 6295(gg)(2)(A)) If an integrated test procedure is technically infeasible, DOE must prescribe separate standby mode and off mode energy use test procedures for the covered product, if a separate test is technically feasible. (

Id.

) Any such amendment must consider the most current versions of the International Electrotechnical Commission (“IEC”) Standard 62301

and IEC Standard 62087

as applicable. (42 U.S.C. 6295(gg)(2)(A))

IEC 62301,

Household electrical appliances—Measurement of standby power

(Edition 2.0, 2011-01).

IEC 62087,

Audio, video and related equipment—Methods of measurement for power consumption

(Edition 1.0, Parts 1-6: 2015, Part 7: 2018).

DOE is publishing this final rule in satisfaction of the 7-year review requirement specified in EPCA. (42 U.S.C. 6293(b)(1)(A))

B. Background

As stated, DOE's existing test procedure for consumer boilers appears at Title 10 of CFR part 430, subpart B, appendix N,

Uniform Test Method for Measuring the Energy Consumption of Furnaces and Boilers

(“appendix N”) and is used to determine the annual fuel utilization efficiency (“AFUE”), which is the regulatory metric for consumer boilers.

DOE most recently updated its test procedure for consumer boilers in a final rule published in the

Federal Register

on January 15, 2016 (“January 2016 Final Rule”). 81 FR 2628. The January 2016 Final Rule amended the existing DOE test procedure for consumer boilers to improve the consistency and accuracy of test results generated using the DOE test procedure and to reduce test burden. In particular, the modifications relevant to consumer boilers included: (1) clarifying the definition of the electrical power term “PE”; (2) adopting a smoke stick test for determining whether minimum default

draft factors can be applied; (3) allowing for optional measurement of condensate during establishment of steady-state conditions; (4) updating references to the applicable installation and operation (“I&O”) manual and providing clarifications for when the I&O manual does not specify test setup; and (5) revising the AFUE reporting precision. DOE also revised the definitions of several terms in the test procedure and added an enforcement provision to provide a method of test for DOE to determine compliance with the automatic means design requirement mandated by the Energy Independence and Security Act of 2007, Public Law 110-140 (Dec. 19, 2007). 81 FR 2628, 2629-2630.

On May 15, 2020, DOE published in the

Federal Register

a request for information (“May 2020 RFI”) seeking comments on the existing DOE test procedure for consumer boilers, which incorporates by reference ANSI/ASHRAE Standard 103-1993. 85 FR 29352. ANSI/ASHRAE 103-1993 provides test procedures for determining the AFUE of residential central furnaces and boilers. In the May 2020 RFI, DOE requested comments, information, and data about a number of issues, including: (1) the test procedure's scope and definitions; (2) updates to industry standards; (3) ambient test conditions; (4) provisions for testing boilers with manually adjustable combustion airflow; (5) calculation of steady-state heat loss for condensing, modulating boilers; and (6) provisions for testing step modulating boilers.

Id.

at 85 FR 29354-29357. DOE also sought comment generally on whether the current test procedures are reasonably designed to produce results that measure energy efficiency during a representative average use cycle or period of use, whether any potential amendments would make the test procedure unduly burdensome to conduct, whether existing test procedures limit a manufacturer's ability to provide additional features, the impact of any potential amendments on manufacturers including small businesses, whether there are any potential issues related to emerging smart technologies, and generally any other aspect of the test procedure for consumer boilers.

Id.

at 85 FR 23957.

On March 15, 2022, DOE published in the

Federal Register

a notice of proposed rulemaking (“March 2022 NOPR”) proposing to amend the current test procedure to incorporate by reference the most current revision to the applicable industry standard that was available at the time, ANSI/ASHRAE 103-2017, “Methods of Testing for Annual Fuel Utilization Efficiency of Residential Central Furnaces and Boilers,” as well as updating the definitions to reflect the changes in ANSI/ASHRAE 103-2017 as compared to the version of the standard currently incorporated by reference (

i.e.,

ANSI/ASHRAE 103-1993). 87 FR 14624. In addition, the March 2022 NOPR proposed to update appendix N to remove the provisions applicable only to consumer boilers and to rename the appendix “Uniform Test Method for Measuring the Energy Consumption of Furnaces.” Correspondingly, DOE proposed to relocate the test procedure specific to consumer boilers at 10 CFR 430 subpart B to a new appendix, EE, “Uniform Test Method for Measuring the Energy Consumption of Boilers” (“appendix EE”).

Id.

On April 7, 2022, DOE held a public meeting via webinar to solicit feedback from stakeholders on the requests for comment in the March 2022 NOPR.

DOE received comments in response to the March 2022 NOPR from the interested parties listed in Table I.1.

Table I.1—List of Commenters With Written Submission in Response to the March 2022 NOPR

Commenter(s)

Reference in this final rule

Comment

No. in

the docket

Commenter type

American Gas Association and American Public Gas Association

AGA and APGA

Utility Associations.

Air-Conditioning, Heating, and Refrigeration Institute

AHRI

Trade Association.

A.O. Smith Corporation

A.O. Smith

Manufacturer.

John Busse

Busse

Individual.

Bradford White Corporation

BWC

Manufacturer.

Pacific Gas and Electric Company, San Diego Gas and Electric, and Southern California Edison (collectively, the California Investor-Owned Utilities)

CA IOUs

Utilities.

Crown Boiler Company

Crown

Manufacturer.

Appliance Standards Awareness Project, American Council for an Energy-Efficient Economy, Consumer Federation of America, National Consumer Law Center Natural Resources Defense Council, and Northwest Energy Efficiency Alliance

Joint Advocates

Efficiency Organizations.

New York State Energy Research and Development Authority

NYSERDA

State Agency.

Rheem Manufacturing Company

Rheem

Manufacturer.

U.S. Boiler Company

U.S. Boiler

Manufacturer.

A parenthetical reference at the end of a comment quotation or paraphrase provides the location of the item in the public record.

To the extent that interested parties have provided written comments that are substantively consistent with any oral comments provided during the April 7, 2022, public meeting, DOE cites the written comments throughout this final rule. DOE did not identify any oral comments provided during the webinar that are not substantively addressed by written comments.

The parenthetical reference provides a reference for information located in the docket of DOE's rulemaking to develop test procedures for consumer boilers. (Docket No. EERE-2019-BT-TP-0037, maintained at

www.regulations.gov.

) The references are arranged as follows: (commenter name, comment docket ID number, page of that document).

II. Synopsis of the Final Rule

In this final rule, DOE updates appendix N to remove the provisions applicable only to consumer boilers and to rename the appendix “Uniform Test Method for Measuring the Energy Consumption of Furnaces.” Correspondingly, this final rule establishes a new test procedure specific to consumer boilers in a new appendix EE. In appendix EE, DOE includes all provisions currently included in appendix N relevant to consumer boilers, with the following modifications:

(1) Incorporate by reference the current version of the applicable industry standard, ANSI/ASHRAE 103-2017, “Methods of Testing for Annual Fuel Utilization Efficiency of

Residential Central Furnaces and Boilers,” which includes several updates to the test method.

(2) Incorporate by reference the current version of ASTM Standard D2156-09 (Reapproved 2018), “Standard Test Method for Smoke Density in Flue Gases from Burning Distillate Fuels.”

(3) Incorporate by reference ANSI/ASHRAE 41.6-2014, “Standard Method for Humidity Measurement.”

(4) Update the definitions to reflect the changes in ANSI/ASHRAE 103-2017 as compared to ANSI/ASHRAE 103-1993.

(5) Provide corrections to erroneous calculations and add clarifications to test conditions and setup requirements.

DOE is also removing the definition of “outdoor furnace or boiler” from 10 CFR 430.2.

The adopted amendments are summarized in Table II.1 compared to the test procedure provision prior to the amendment, as well as the reason for the adopted change.

Table II.1—Summary of Changes in the Amended Test Procedure

DOE test procedure prior to amendment

Amended test procedure

Attribution

Incorporated by reference industry standard ANSI/ASHRAE 103-1993

Incorporates by reference ANSI/ASHRAE 103-2017 in the new appendix EE

Harmonization with industry standard update.

Incorporated by reference the procedure for adjusting oil-fired burner by referencing industry standard ASTM D2156-09 (Reapproved 2013)

Incorporates by reference the procedure for adjusting oil-fired burner by referencing industry standard ASTM D2156-09 (Reapproved 2018) in the new appendix EE

Harmonization with industry standard update.

Limited the maximum relative humidity of the test room during certain tests but did not provide specific instructions for how to measure relative humidity

Incorporates by reference ANSI/ASHRAE 41.6-2014 instructions for measuring relative humidity of the test room in the new appendix EE

Referenced by industry standard ANSI/ASHRAE 103-2017, which is being incorporated by reference in this final rule.

Included a definition for “outdoor furnace or boiler” at 10 CFR 430.2

Removes the definition for “outdoor furnace or boiler”

Unused definition.

Included an undefined term, “standard cubic foot of gas”

Adds a definition for “standard cubic foot of gas” in new appendix EE

Increase clarity for testing conditions.

Defined “control” and “isolated combustion system” in appendix N

Adopts the definitions for the terms “control” and “isolated combustion system” from ASHRAE 103-2017 in new appendix EE

Harmonization with industry standard update.

Referenced calculations in ANSI/ASHRAE 103-1993 which yielded a circular reference when calculating the steady-state efficiency for condensing modulating boilers

Includes an amended calculation for balance-point temperature (T

) which resolves the circular reference in new appendix EE

Correction.

Referenced Table 9 in ANSI/ASHRAE 103-1993, which assigned fixed values for the average on-time and off-time per cycle for two-stage and modulating boilers

References Table 7 of ANSI/ASHRAE 103-2017 in the new appendix EE, which uses calculations for determining the average on-time and off-time per cycle for two-stage and modulating boilers

Harmonization with industry standard update.

Specified cycle times (t

and t

OFF

) to a fraction of a second through reference to ANSI/ASHRAE 103-1993 Table 9

Provides additional specification in appendix EE to require that calculated cycle timings shall be rounded to the nearest second

Clarification to reduce test burden.

Calculated oversize factor from a lookup table based on design heating requirement (“DHR”) in ANSI/ASHRAE 103-1993

Adopts the ANSI/ASHRAE 103-2017 methodology of assigning a constant value of 0.70 to α to represent the national average oversize factor in appendix EE

Harmonization with industry standard update.

Used a purge time limit of 5 seconds to determine whether heat-up and cool-down tests may be optionally omitted, whereas a purge time limit of 30 seconds was used to determine whether a post-purge (t

) of 0 seconds could be assigned in calculations

Applies the 30-second limit in appendix EE for determining when the heat-up and cool-down tests may be optionally omitted

Harmonization with industry standard update.

Limited the maximum value of post-purge (t

) to 180 seconds if a purge time of greater than 3 minutes was observed

Removes the maximum value of 180 seconds in appendix EE and requires an additional temperature measurement to be taken if the post-purge is greater than 3 minutes

Harmonization with industry standard update.

Referenced calculations for off-cycle infiltration losses in ANSI/ASHRAE 103-1993 which had a typographical error where the conversion from minutes to hours was performed incorrectly

Specifies the correct calculation for off-cycle infiltration losses through reference to ANSI/ASHRAE 103-2017 and corrects minutes to hours conversion error in new appendix EE

Correction.

Provided inconsistent unit conversion factor from watts (“W”) to British thermal units per hour (“Btu/h”), using values of 3.412 or 3.413

Corrects the conversion factor from W to Btu/h to 3.412 throughout new appendix EE

Correction.

Required the use of a gas having a specific gravity as shown in Table 1 of ANSI/ASHRAE 103-1993

Requires the use of a gas having a specific gravity “approximate” to what is shown in Table 1 of ANSI/ASHRAE 103-2017 in the new appendix EE

Clarification to reduce test burden.

Referenced incorrect sections of appendix N test procedure regarding average annual auxiliary electrical consumption determination provisions at 10 CFR 430.23(n)(1)

Revises 10 CFR 430.23(n)(1) to update references regarding average annual auxiliary electrical consumption to the correct sections of appendix N and the new appendix EE

Correction.

Referenced values in ANSI/ASHRAE 103-1993 for determining national average burner operating hours (“BOH”), average annual fuel energy consumption (“EF”), and average annual auxiliary electrical energy consumption (“E

”)

References values in ANSI/ASHRAE 103-2017 for determining national average BOH, average annual EF, and average annual E

in the new appendix EE

Harmonization with industry standard update.

Included instructions for the setup of boilers with draft hoods or draft diverters which specified a minimum R-value for insulation but did not specify the units of measure for R-value

Includes units of measure for R-value in the new appendix EE

Correction.

DOE has determined that the amendments described in section III of this document and adopted in this final rule will not substantively impact the measured efficiency of consumer boilers or require retesting or recertification solely as a result of DOE's adoption of the amendments to the test procedures. Additionally, DOE has determined that the amendments will not increase the cost of testing. Discussion of DOE's actions is addressed in detail in section III of this document.

The effective date for the amended test procedures adopted in this final rule is 30 days after publication of this document in the

Federal Register

. Representations of energy use or energy efficiency must be based on testing in accordance with the amended test procedures beginning 180 days after the publication of this final rule.

III. Discussion

The subsequent sections of this final rule discuss specific topics raised in this rulemaking, including comments DOE received in response to the March 2022 NOPR. These topics include: scope of applicability of the test procedure, definitions in the test procedure, the AFUE metric, updates to industry standards, clarifications and corrections to the current test procedure, and test conditions.

In addition, DOE received comments relating to the general processes by which DOE amends test procedures and energy conservation standards for covered products and equipment.

BWC urged DOE to consider the cumulative regulatory burden placed on manufacturers that produce several different types of regulated products for which there are simultaneous rulemakings. BWC noted that additional burdens on manufacturers include changes to ENERGY STAR specifications; the Securities and Exchange Commission's proposed rule to enhance and standardize climate-related disclosures; updated state and local codes; demand-response requirements for electric water heaters in Western States; lower nitrogen oxides (NO

) emissions proposals in the State of California; proposed amendments to California Proposition 65; and extended producer responsibility legislation recently enacted in both Maine and Oregon. (BWC, No. 19 at p. 4-5)

In response, DOE notes that cumulative regulatory burden on manufacturers is assessed as part of energy conservation standards rulemakings. The amendments to the consumer boilers test procedure, as promulgated by this final rule, are not expected to add burden to manufacturers because the amendments do not substantially impact efficiency ratings or alter the type of equipment necessary to perform testing. Test costs and burden are discussed in section III.K of this document.

AGA and APGA commented that DOE should implement the recommendations from the recent National Academies of Sciences, Engineering, and Medicine report (“NASEM report”)

into all of its appliance rulemakings for test procedures or energy conservation standards. AGA and APGA reiterated recommendations pertaining to analyses that DOE conducts in order to determine whether potential new or amended energy conservation standards are technologically feasible and economically justified. (AGA and APGA, No. 25, p. 3) For example, AGA and APGA highlighted the NASEM report's recommendations that DOE pay greater attention to the justification for its standards, expand the Cost Analysis segment of the Engineering Analysis for its rules, put greater weight on ex post and market-based evidence markups, place greater emphasis on providing an argument for the plausibility and magnitude of any market failure related to the energy efficiency gap, and give greater attention to a broader set of potential market failures on the supply side.

Id.

Although not specified, DOE interprets this comment to refer to the National Academies of Science, Engineering, and Medicine 2021 report entitled “Review of Methods Used by the U.S. Department of Energy in Setting Appliance and Equipment Standards.” Copies of the report are available at

nap.nationalacademies.org/catalog/25992/review-of-methods-used-by-the-us-department-of-energy-in-setting-appliance-and-equipment-standards.

Given that this is a test procedure rulemaking for which DOE must meet specific statutory criteria as outlined in 42 U.S.C. 6293(b)(3), the recommendations in the NASEM report which pertain specifically to the processes by which DOE analyzes energy conservation standards are misplaced. DOE will consider this comment in a separate rulemaking considering all product categories.

A. Scope of Applicability

As discussed, in the context of “covered products,” EPCA includes boilers in the definition of “furnace.” (42 U.S.C. 6291(23)) EPCA defines the term “furnace” to mean a product which utilizes only single-phase electric current, or single-phase electric current or DC current in conjunction with natural gas, propane, or home heating oil, and which: (1) is designed to be the principal heating source for the living space of a residence; (2) is not contained within the same cabinet with a central air conditioner whose rated cooling capacity is above 65,000 Btu/h; (3) is an electric central furnace, electric boiler, forced-air central furnace, gravity central furnace, or low pressure steam or hot water boiler; and (4) has a heat input rate of less than 300,000 Btu/h for electric boilers and low pressure steam or hot water boilers and less than 225,000 Btu/h for forced-air central furnaces, gravity central furnaces, and electric central furnaces.

Id.

DOE has codified this definition in its regulations at 10 CFR 430.2.

DOE defines “electric boiler” as an electrically powered furnace designed to supply low pressure steam or hot water for space heating application. A low pressure steam boiler operates at or below 15 pounds per square inch gauge (“psig”) steam pressure; a hot water boiler operates at or below 160 psig water pressure and 250 degrees Fahrenheit (°F) water temperature. 10 CFR 430.2.

DOE defines “low pressure steam or hot water boiler” as an electric, gas or oil burning furnace designed to supply low pressure steam or hot water for space heating application. 10 CFR 430.2. As with an electric boiler, a low pressure steam boiler operates at or below 15 pounds psig steam pressure; a hot water boiler operates at or below 160 psig water pressure and 250 °F water temperature.

Id.

The scope of the test procedure for consumer boilers is currently specified

in section 1 of appendix N, which references section 2 of ANSI/ASHRAE 103-1993. In relevant part, section 2 of ANSI/ASHRAE 103-1993 states that the industry test standard applies to boilers

with inputs less than 300,000 Btu/h; having gas, oil, or electric input; and intended for use in residential applications. Further, ANSI/ASHRAE 103-1993 applies to equipment that utilizes single-phase electric current or low-voltage DC current.

ASHRAE 103-1993 defines a boiler as “a self-contained fuel-burning or electrically heated appliance for supplying low pressure steam or hot water for space heating application.” This definition covers electric boilers and low pressure steam or hot water boilers as those terms are defined by DOE at 10 CFR 430.2.

DOE is not changing the scope of products covered by its consumer boiler test procedure in this final rule. The following sections discuss specific types of boilers that DOE addressed in the March 2022 NOPR with respect to whether such products are covered by the scope of DOE's test procedure.

1. Combination Space/Water Heating Boilers

Some consumer boilers are capable of providing both space heating and domestic hot water heating, and are often referred to as “combination” boilers. In the March 2022 NOPR, DOE responded to comments from the Northwest Energy Efficiency Alliance (“NEEA”) and Rheem recommending that DOE consider developing a separate test procedure for combination space and domestic hot water boilers. 87 FR 14622, 14626-14627. While DOE did not propose a specific definition for combination space and water heating boilers in the NOPR, DOE noted that, to the extent that a combination space and water heating product meets the definition of electric boiler or low pressure steam or hot water boiler, it is subject to the test procedure at appendix N and energy conservation standards for consumer boilers at 10 CFR 430.32(e)(2), and must be tested and rated accordingly. 87 FR 14622, 14625-14626. DOE also stated that it is unaware of any design characteristics of combination space and water heating products that would prevent their testing according to appendix N.

Id.

DOE did not receive any comments in response to the March 2022 NOPR with regard to combination space and heating water boilers. In this final rule, DOE reiterates its statements presented in the March 2022 NOPR with respect to combination boilers. To the extent that a combination space and water heating product meets the definition of electric boiler or low pressure steam or hot water boiler, it is subject to the test procedure at appendix N (or, as of the effective date of this final rule, appendix EE) and energy conservation standards for consumer boilers at 10 CFR 430.32(e)(2), and must be tested and rated accordingly.

2. Heat Pump Boilers

In the March 2022 NOPR, DOE discussed comments received in response to the May 2021 RFI with regard to hydronic air-to-water and water-to-water heat pumps. DOE tentatively determined that air-to-water and water-to-water heat pumps meet the definitional criteria to be classified as a consumer boiler. 87 FR 14622, 14625. DOE noted that these products utilize only single-phase electric current, are designed to be the principal heating source for the living space of a residence, are not contained within the same cabinet with a central air conditioner whose rated cooling capacity is above 65,000 Btu/h, meet the definition of an electric boiler,

and have a heat input rate of less than 300,000 Btu/h (

i.e.,

the requirement for electric boilers). As such, they meet the criteria of “furnace” as defined in 10 CFR 430.2.

Id.

at 87 FR 14625-14626.

“Electric boiler” means an electrically powered furnace designed to supply low pressure steam or hot water for space heating application. A low pressure steam boiler operates at or below 15 psig steam pressure; a hot water boiler operates at or below 160 psig water pressure and 250 °F water temperature. 10 CFR 430.2.

In the March 2022 NOPR, DOE also tentatively determined that the test procedure in appendix N does not address such products and would not provide a rated value that is representative of the performance of these products.

Id.

at 14626. In particular, DOE noted that the AFUE metric for electric boilers in ANSI/ASHRAE 103-1993 is calculated as 100 percent minus jacket loss,

which provides a representative measure of efficiency for electric boilers using electric resistance technology, for which an efficiency value of 100 percent (the ratio of heat output to energy input) is the maximum upper limit that technically could be achieved. DOE tentatively concluded that the AFUE metric would not provide a representative or meaningful measure of efficiency for a boiler with a heat pump supplying the heat input, because heat pump efficiency (in terms of heat output to energy input) typically exceeds 100 percent, and the AFUE metric does not allow for ratings greater than 100 percent for electric boilers.

Id.

The term “jacket loss” is used by industry to mean the transfer of heat from the outer surface (

i.e.,

jacket) of a boiler to the ambient air surrounding the boiler.

Based on these considerations, DOE tentatively determined that hydronic air-to-water and water-to-water heat pumps are consumer boilers under EPCA, but that due to the lack of a Federal test procedure, such products are not subject to the current performance standards at 10 CFR 430.32(e).

Id.

In response to the March 2022 NOPR, Crown and U.S. Boiler

stated that hydronic heat pumps should not be classified as boilers under EPCA because hydronic heat pumps cannot deliver water at the same temperatures and heating capacities as traditional boilers. Crown and U.S. Boiler further commented that it is unclear whether hydronic heat pumps are “designed to be the principal heating source for a living space of a residence” (a requirement to meet the definition of a furnace at 10 CFR 430.2) because these products are mostly incapable of reaching above 150 °F on a design day, whereas traditional boilers are designed to deliver water at a temperature of 180 °F or higher. Crown and U.S. Boiler also stated that gas, oil, and electric resistance boilers are capable of heating any hot water or steam heating system throughout the entire heating season, whereas hydronic heat pumps do not have such capabilities. Crown and U.S. Boiler stated that heat pumps and boilers provide different consumer utility, and suggested that presenting heat pumps to consumers as “boilers” could create confusion with regard to the different capabilities of each. (Crown, No. 16 at p. 1-2; -U.S. Boiler, No. 17 at p. 1-2)

DOE notes that both Crown and U.S. Boiler's comments stated that the companies are subsidiaries of Burnham Holdings, Inc. (“BHI”). The comments submitted by Crown and U.S. Boiler in response to the March 2022 NOPR were identical in content.

AHRI and AGA and APGA commented that hydronic heat pumps cannot currently provide the same functionality as boilers for high temperature installations as they are unable to provide water at or over 210 °F, and that this lack of utility should disqualify these products from being considered in the boiler test procedure. (AHRI, No. 26 at p. 2; AGA and APGA, No. 25 at p. 2)

BWC disagreed with DOE's tentative determination that air-to-water and water-to-water heat pumps should be defined as consumer boilers. BWC stated that heat pump products and consumer boilers have pronounced differences that should prevent them from being defined as the same product.

BWC noted that boilers and heat pumps

are already separate product categories on DOE's website and certified separately through DOE's Compliance Certification Management System. BWC also stated that hydronic heat pumps are rated to Coefficient of Performance (“COP”) rather than AFUE (for boilers), and that the unique technologies utilized by both product types necessitate different methods for testing and rating them. BWC further stated that consumer boilers are designed exclusively to provide a heating utility, whereas hydronic heat pumps can be used to provide both space heating and cooling. (BWC, No. 19 at p. 2-3)

DOE understands BWC is referring to central air conditioning and heat pump units.

Rheem supported DOE's tentative determination that hydronic air-to-water and water-to-water heat pumps are consumer boilers under EPCA. Rheem stated that although these products may not necessarily be able to achieve the same maximum temperatures as conventional boilers (without electric resistance or gas backup), hydronic heat pump boilers can still provide adequate space heating in many applications. Rheem recommended that DOE either add procedures to test hydronic heat pumps in this consumer boiler test procedure rulemaking or initiate a separate test procedure rulemaking. Rheem asserted that these products perform the same function as other types of boilers and should be tested and rated in a similar manner, and that DOE could use the current AFUE test procedure as a guide to produce an “AFUE metric” for hydronic heat pumps that combines the various energy use modes and input rate conditions with test conditions and operating assumptions that are representative of hydronic heat pumps. Rheem stated that any differences in ability to meet consumer heating demands should be considered in the development of energy conservation standards, as opposed to the test procedure. (Rheem, No. 18 at p. 2)

NYSERDA agreed with DOE's tentative determination that air-to-water and water-to-water heat pumps should be considered boilers under EPCA. NYSERDA recommended that DOE develop a test procedure for these heat pumps and combination space heating and water heating products. NYSERDA asserted that the adoption of these test procedures will also enable future standards revisions to adopt more efficient heat pump levels of performance. (NYSERDA, No. 23 at p. 5-6)

In consideration of the comments received on this issue, as well as further consideration of the discussion presented in the March 2022 NOPR, DOE has concluded that hydronic air-to-water and water-to-water heat pumps meet the definitional criteria to be classified as a consumer boiler. In particular, as noted initially in the March 2022 NOPR, DOE concludes that these products utilize only single-phase electric current, are designed to be the principal heating source for the living space of a residence, and are not contained within the same cabinet with a central air conditioner whose rated cooling capacity is above 65,000 Btu/h. In addition, electric heat pump boilers meet the definition of an electric boiler; and gas-fired heat pump boilers meet the definition of a low pressure steam or hot water boiler and have a heat input rate of less than 300,000 Btu/h (

i.e.,

the requirement for electric boilers and low pressure steam or hot water boilers). As such, these products meet the criteria of “furnace” as defined in 10 CFR 430.2.

With respect to comments from Crown, U.S. Boiler, AHRI, and AGA and APGA suggesting hydronic air-to-water heat pumps and water-to-water heat pumps should be excluded from the definition because they cannot provide the same maximum water temperature as non-heat pump hydronic systems, DOE notes that neither EPCA nor DOE's definitions at 10 CFR 430.2 provide a minimum water temperature requirement. In addition, in response to comments that hydronic heat pumps serve different applications than boilers, DOE notes that hydronic heat pumps are marketed as providing the principal heating source for a residence, and nothing in EPCA's or DOE's definition would exclude them based on their ability to also provide cooling.

DOE recognizes that hydronic heat pump products differ significantly from non-heat pump boilers, and that the current test procedure for consumer boilers (as well as the amended test procedure established by this final rule) would not provide test results that are representative of the energy use or energy efficiency of an air-to-water or water-to-water heat pump product. Because of these differences and uncertainty regarding the most representative approach to testing these products, DOE is not establishing separate test procedures for hydronic heat pump products in this final rule. Although air-to-water and water-to-water heat pump products meet all the definitional criteria to be considered a consumer boiler, the Department requires more information in order to determine a representative approach for testing these products. Further consideration of an appropriate test procedure for such products would be provided in a separate test procedure rulemaking. Section III.C of this document further discusses the applicability of the AFUE metric to hydronic heat pump products.

B. Definitions

In addition to the overarching definition of “furnace” (which includes boilers) and the associated definitions for “electric boiler” and “low pressure steam or hot water boiler” presented in section III.A of this document, DOE also has defined “outdoor boilers” and “weatherized warm air boilers” at 10 CFR 430.2 as follows:

• “Outdoor furnace or boiler” is a furnace or boiler normally intended for installation out-of-doors or in an unheated space (such as an attic or a crawl space).

• “Weatherized warm air furnace or boiler” means a furnace or boiler designed for installation outdoors, approved for resistance to wind, rain, and snow, and supplied with its own venting system.

In the March 2022 NOPR, DOE proposed to remove the definition of “outdoor furnace or boiler” from its regulations, noting that the definition is not used for the energy conservation standards for boilers at 10 CFR 430.32(e)(2)(iii), nor for applying the test procedure.

87 FR 14622, 14626-14627. DOE sought comment on its proposal to remove the definition of “outdoor furnace or boiler” from its regulations and whether removing the definition for “outdoor furnace or boiler” would impact the application of the test procedure or energy conservation standards for any such products.

Specifically, with respect to the test procedure, DOE noted that different jacket loss factors are applied based on whether a boiler is intended to be installed indoors, outdoors, or as an isolated combustion system. The heating seasonal efficiency (Effy

) calculation, which is an element of AFUE, is based on the assumption that all weatherized boilers are located outdoors (see section 10.1 of appendix N). Appendix N does not specify a separate jacket loss assumption for outdoor furnaces or boilers.

Rheem and BWC supported DOE's proposal to remove the definition of “outdoor furnace or boiler” from 10 CFR 430.2. (Rheem, No. 18 at p. 2; BWC, No. 19 at p. 1) A.O. Smith stated that removal of this definition from the DOE regulations would not have a negative impact on the application of the test procedure or energy conservation standards. (A.O. Smith, No. 24 at p. 2) AHRI and AGA and APGA also supported removing the definition and

stated that the removal would add clarity and consistency to the test procedure. (AHRI, No. 26 at p. 2; AGA and APGA, No. 25 at p. 2)

For the reasons discussed in the March 2022 NOPR, and in consideration of these comments, in this final rule DOE finalizes its proposal to remove the definition of “outdoor furnace or boiler” from 10 CFR 430.2.

In the March 2022 NOPR, DOE proposed to incorporate by reference ANSI/ASHRAE 103-2017, including the definitions included therein. 87 FR 14622, 14627. DOE noted that ANSI/ASHRAE 103-2017 includes definitions for “air intake terminal,” “control,” and “isolated combustion system” that are not in ANSI/ASHRAE 103-1993.

Id.

The definitions for “control” and “isolated combustion system” in ANSI/ASHRAE 103-2017 are almost identical to the definitions for those terms currently defined in sections 2.3 and 2.7 of appendix N, respectively. Therefore, DOE proposed to remove the definitions for “control” and “isolated combustion system” from DOE's consumer boiler test procedure, as they would be redundant with the definitions incorporated by reference through ANSI/ASHRAE 103-2017, if the proposal to incorporate by reference ANSI/ASHRAE 103-2017 were finalized.

Id.

Rheem, The CA IOUs, A.O. Smith, AHRI, and AGA and APGA supported incorporating by reference the definitions in ANSI/ASHRAE 103-2017 and removing the separate definitions for “control” and “isolated combustions system” from DOE's test procedure. (Rheem, No. 18 at p. 3; CA IOUs, No. 20 at p. 1; A.O. Smith, No. 24 at p. 3; AHRI, No. 26 at p. 2; AGA and APGA, No. 25 at p. 2)

For the reasons discussed in the March 2022 NOPR, and in consideration of these comments, DOE is removing the separate definitions for “control” and “isolated combustion system” from the consumer boiler test procedure, as proposed in the March 2022 NOPR. The definitions for these products are instead provided through DOE's incorporation by reference of ANSI/ASHRAE 103-2017, as discussed further in section III.D.1 of this final rule.

In response to the March 2022 NOPR, Busse suggested that DOE add a definition for “standard cubic unit of gas” as follows:

“Standard cubic foot of gas: The amount of gas that would occupy 1 cubic foot when at a temperature of 60 °F, if saturated with water vapor, and under a pressure equivalent to that of 30 inches mercury column.” (Busse, No. 22 at p. 9)

Busse stated that a definition of standard cubic foot of gas is necessary to comply with the conditions specified in section 7.1 of appendix N,

Fuel Supply.

Busse further stated that the suggested definition would be consistent with industry standards NFPA 54/ANSI Z223.1,

National Fuel Gas Code,

and CSA 4.9/ANSI Z21.13,

Gas-Fired Low Pressure Steam and Hot Water Boilers

and asserted that manufacturers are familiar with this definition when conducting performance testing. Busse noted that the difference between a saturated “wet” and unsaturated “dry” cubic foot of gas is 1.73 percent at standard temperature and pressure. Busse also recommended that DOE modify the language of section 7.3 of appendix N,

Gas Burner,

to replace “gas characteristics at a temperature of 60 °F and atmospheric pressure of 30 in of Hg” with reference to this new definition,

i.e.,

“gas characteristics to standard cubic foot of gas, as defined in section 2 of this appendix,” in specifying the conditions needed to correct the burner input rate.

(Busse, No. 22 at p. 9-10)

Section 7.1 of appendix N requires determining the actual higher heating value in Btu per standard cubic foot for the gas to be used in the test within an error no greater than 1 percent.

Busse also commented that, with respect to the current instruction to “Correct the burner input rate to reflect gas characteristics,” technically the Ideal Gas Laws can be applied only to the volume of gas consumed and the higher heating value, and not to the burner input rate.

In response, DOE notes that as proposed in the March 2022 NOPR, section 7.3 of appendix EE would require that the burner input rate be corrected to reflect gas characteristics at a temperature of 60 °F and atmospheric pressure of 30 in of Hg when adjusting the burner input rate. Therefore, an additional definition for a standard cubic foot of gas for the purpose of referencing it in sections 7.1 and 7.3 (which is consistent with the language in section 9.1.2.2.1 of both ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017) would be unnecessary; however, it may be useful for clarification.

As such, DOE is adding a definition for a “standard cubic foot of gas” to section 2 of appendix EE to specify the temperature and pressure for a standard cubic foot of gas.

C. Metric

As discussed, the energy conservation standards for consumer boilers rely on the AFUE metric. 10 CFR 430.32(e)(2). For gas-fired and oil-fired boilers, AFUE accounts for fossil fuel consumption in active, standby, and off modes, but does not include electrical energy consumption. For electric boilers, AFUE accounts for electrical energy consumption in active mode. EPCA defines the term “annual fuel utilization efficiency,” in part, as the efficiency descriptor for furnaces and boilers. (42 U.S.C. 6291(20)) In addition, DOE has established separate metrics and energy conservation standards for power consumption during standby mode and off mode (P

W,SB

and P

W,OFF

, respectively). 10 CFR 430.32(e)(2)(iii)(B).

AFUE is defined by ASHRAE 103 (both the 1993 and 2017 versions) as the ratio of annual output energy to annual input energy, which includes any non-heating-season pilot input loss but does not include electric energy for gas- or oil-fired furnaces or boilers. For gas- and oil-fired boilers, the AFUE test generally consists of steady-state, cool down, and heat up tests, during which various measurements are taken (

e.g.,

flue gas temperature, concentration of CO

in the flue gas). (

See

sections 9.1, 9.5, and 9.6 of both ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017.) For condensing boilers, condensate collection tests during steady-state and cyclic operation are also specified. (

See

sections 9.2 and 9.8 of both ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017.) The test measurements are used in conjunction with certain assumptions to calculate the AFUE. (

See

section 11 of both ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017.)

In the March 2022 NOPR, after tentatively concluding that hydronic heat pumps meet the definitional criteria to be considered a consumer boiler but that the existing test procedure does not apply to them, DOE sought comment on whether any other industry test methods exist for determining the heating efficiency of air-to-water or water-to-water heat pumps. DOE sought comment specifically on AHRI 550/590, and whether it would be appropriate for adoption as a Federal test procedure for such products, and if so, whether modifications could be made to result in an AFUE rating. 87 FR 14622, 14626.

NYSERDA urged DOE to adopt appropriate, industry-recognized test procedures to support informed consumer choice between electric resistance and heat pump products. (NYSERDA, No. 23 at p. 5-6)

BWC stated that it believes DOE has correctly identified the appropriate test procedures for both consumer boilers and hydronic heat pumps at this time, with those procedures being ASHRAE 103-2017 and AHRI 550/590 respectively. (BWC, No. 19 at p 2-3)

Rheem identified AHRI 550/590 as an industry test method to determine maximum and part-load COP values but noted this test method would have to be modified to account for standby mode and off mode energy use as well as to produce an AFUE metric. (Rheem, No. 18 at p. 2)

The Joint Advocates stated that while AHRI 550/590 is appropriate for evaluating the performance of consumer air-to-water heat pumps, it is only applicable for water-to-water heat pumps with a capacity greater or equal to 135,000 Btu/h. The Joint Advocates stated that ASHRAE/ANSI/AHRI/ISO Standard 13256-2 is more appropriate for consumer water-to-water heat pumps and referred to international standards EN 14511 and EN 14825 as starting points. The Joint Advocates asserted that a seasonal performance rating analogous to AFUE could be established and encouraged DOE to establish these procedures in a timely manner so that consumers have access to efficiency ratings based on a standardized test procedure. Finally, the Joint Advocates stated that based on 2015 Residential Energy Consumption Survey (“RECS”) data, hydronic systems are the main heating means in 8 percent of U.S. homes overall and the main heating means for 28 percent of households in the Northeastern United States. (Joint Advocates, No. 21 at p. 1-2)

A.O. Smith stated that ISO Standard 13256-2 would be the most appropriate test method for water source heat pump water heaters intended to be used as consumer hot water boilers, and that AHRI Standard 550/590 would be the most appropriate test method for air source heat pump water heaters intended to be used as consumer hot water boilers. Pertaining specifically to AHRI 550/590, A.O. Smith stated that the test procedure to measure COP has fundamental differences than the test procedure to measure AFUE, and that there is no means of deriving an AFUE value from the COP measurement. In addition, A.O. Smith claimed that if the limit for consumer heat pump water “boilers” is defined by an input rate of less than 300,000 Btu/h, then the output for these products will include products with heating capacities up to 900,000 Btu/h, which would be outside the scope of a consumer boiler. A.O. Smith recommended that DOE review the referenced performance standards, as they define the heating capacity based on the heat moved into the water being heated, whereas DOE's definition is based on the energy being consumed by the boiler. (A.O. Smith, No. 24 at p. 2)

As stated in section III.A.2 of this document, DOE has concluded that hydronic heat pumps meet the definitional criteria to be covered as a consumer boiler under EPCA's statutory definition at 42 U.S.C. 6291(23) and DOE's regulatory definition at 10 CFR 430.2. However, DOE is not adopting a separate test procedure or metric for hydronic heat pumps in this final rule because the Department requires more information in order to determine a representative approach for testing these products. DOE will continue to consider the appropriate metric to assess the efficiency of such products, and any proposed test procedure would be addressed in a separate test procedure rulemaking in the future.

D. Updates to Industry Standards

The DOE test method for consumer boilers references several industry standards, including ANSI/ASHRAE 103 for various testing requirements pertaining to determination of AFUE, certain sections of IEC 62301 (Second Edition) for determining the electrical standby mode and off mode energy consumption, and ASTM D2156-09 (Reapproved 2013) for adjusting oil burners. The following sections discuss DOE's amendments pertaining to the incorporation by reference of these industry standards.

1. ANSI/ASHRAE 103

As discussed, ANSI/ASHRAE 103-1993 is referenced throughout appendix N for various testing requirements pertaining to determination of the AFUE of consumer boilers. ANSI/ASHRAE 103-1993 provides procedures for determining the AFUE of consumer boilers (and furnaces). As mentioned previously, ANSI/ASHRAE 103-1993 has been updated multiple times. In the rulemaking that culminated in the January 2016 Final Rule, DOE initially proposed to incorporate by reference the most recent version of ANSI/ASHRAE 103 available at the time (

i.e.,

ANSI/ASHRAE 103-2007), but ultimately declined to adopt the proposal in the final rule based on concerns about the impact this change would have on AFUE ratings of products distributed in commerce at that time. 81 FR 2628, 2632-2633 (Jan. 15, 2016). DOE stated that further evaluation was needed to determine the potential impacts of ANSI/ASHRAE 103-2007 on the measured AFUE of boilers.

Id.

DOE theorized that ANSI/ASHRAE 103-2007 might better account for the operation of two-stage and modulating products and stated that DOE may further investigate adopting it or a successor test procedure in the future.

Id.

After the January 2016 Final Rule, ANSI/ASHRAE 103 was again updated in 2017 (

i.e.,

ANSI/ASHRAE 103-2017). In the May 2020 RFI, DOE identified several substantive differences between ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017 that pertain to consumer boilers and requested further comment on the differences between ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017. 85 FR 29352, 29355.

In the March 2022 NOPR, DOE discussed additional differences between ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017 raised by commenters in response to the May 2020 RFI. 87 FR 14622, 14628-14631. The differences between the two versions of the standard are discussed in detail in sections III.D.1.a through III.D.1.f of this document. After considering the differences between the standards and the potential impact, DOE proposed to incorporate by reference the most recent version (at the time) of ANSI/ASHRAE 103,

i.e.,

ANSI/ASHRAE 103-2017. 87 FR 14622, 14630. DOE tentatively concluded that the improvements included in ANSI/ASHRAE 103-2017 provide a more representative average use cycle for consumer boilers, in particular for two-stage and modulating boilers, and that the change would not materially alter the burden or cost of conducting an AFUE test.

Id.

DOE also noted that test data indicate the update to the 2017 edition of ASHRAE 103 could result in changes to the measured AFUE of two-stage and modulating boilers ranging from -0.50 percent to 0.23 percent, with no discernable trend in the direction or magnitude of change, and that several commenters indicated incorporating ANSI/ASHRAE 103-2017 would likely not impact rated values significantly. 87 FR 14622, 14631. DOE sought further comment on its proposal to incorporate by reference ANSI/ASHRAE 103-2017, the potential impact on ratings and whether retesting would be required.

Id.

Rheem agreed with DOE's tentative determination that the proposed amendments would result in minimal differences in AFUE ratings but requested that DOE test a representative sample of minimally compliant consumer boilers to determine the effect. Rheem requested that DOE provide this test data in the final rule and assess the impacts on the ongoing energy conservation standards rulemaking. Rheem additionally suggested that DOE could provide an enforcement policy to state that models tested and certified prior to the effective date of the test procedure final rule would be tested to the current appendix N test procedure during an enforcement investigation. (Rheem, No. 18 at p. 3-4)

As discussed, DOE's assessment of the changes in ANSI/ASHRAE 103-2017, along with stakeholder comments provided throughout this rulemaking, indicate that the only update in the industry test procedure with the potential to impact ratings would be the change in cycle times. This topic is discussed in detail in section III.D.2.c of this document. The updated cycle times pertain to condensing boilers, which employ heat exchanger technologies with efficiency performance that surpasses the current minimum AFUE requirements for boilers at 10 CFR 430.32(e)(2)(iii). As discussed in section III.D.2.c of this document, DOE conducted testing to determine that the impact on AFUE ratings of this change would be minimal. Based on this information, DOE has determined that the amendments to the consumer boilers test procedure will not have a significant or substantive impact on ratings, nor affect compliance of any products.

On January 10, 2022, ASHRAE and ANSI approved a 2022 edition of ASHRAE 103 (

i.e.,

“ANSI/ASHRAE 103-2022”). DOE did not discuss ANSI/ASHRAE 103-2022 in the March 2022 NOPR, and parties commenting in response to the March 2022 NOPR did not indicate that DOE should consider incorporating by reference ANSI/ASHRAE 103-2022. A March 4, 2022, online publication by ANSI states that ANSI/ASHRAE 103-2022 includes mostly editorial changes and quality improvements to test duct and plenum figure, the system number table, and figures for the surface heat transfer coefficient and coefficient of radiation.

Given that stakeholders provided general support for adopting ANSI/ASHRAE 103-2017, and that the updates in ANSI/ASHRAE 103-2022 do not substantively change the industry test procedure DOE is not considering ANSI/ASHRAE 103-2022 in this rulemaking.

Brad Kelechava, “ANSI/ASHRAE 103-2022: AFUE Testing of Residential Furnaces and Boilers,” The ANSI Blog, March 4, 2022,

blog.ansi.org/ansi-ashrae-103-2022-fuel-efficiency-afue-testing/#gref.

Last accessed October 5, 2022.

The following subsections discuss the updates in ANSI/ASHRAE 103-2017 with respect to ANSI/ASHRAE 103-1993.

a. Post-Purge Time

Power vented units, power burner units, and forced-draft units use a combustion blower to exhaust the flue gas during operation. “Post purge” is defined in both ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017 as “the design that permits the continued operation of the combustion blower in a power vented unit, power burner unit, or forced-draft unit for a period of time after the main burner is shut off for the purpose of venting of residential flue gas in the heat exchanger and the venting system.” For the determination of off-cycle flue losses, it is necessary to demarcate when the boiler has entered its off-cycle after completion of the post-purge period, especially since post-purge periods can last several minutes. Section 8.7 of appendix N specifies the timing of flue temperature measurements during the off-cycle portion of the test method based on the length of the post-purge period. Section 8.7 of appendix N generally corresponds to section 9.5.2.1 of ANSI/ASHRAE 103-1993, except that section 8.7 of appendix N specifies that when the post-purge time is less than or equal to 30 seconds, it can be set to 0 and the cool-down test be conducted as if there is no post-purge; while section 9.5.2.1 of ANSI/ASHRAE 103-1993 specifies that if post-purge time is less than or equal to 5 seconds, it shall be tested as if there is no post-purge. Additionally, the length of the post-purge cycle is used as one criterion for determining whether the heat-up and cool-down tests can optionally be omitted. Section 8.10 of appendix N generally corresponds to section 9.10 of ANSI/ASHRAE 103-1993, and both sections require a post-purge period of less than 5 seconds to optionally omit the heat-up and cool-down tests.

Section 9.5.2.1 of ANSI/ASHRAE 103 was updated in the 2017 version to match DOE's requirement that if the post-purge period is 30 seconds or less, it shall be tested as if there is no post-purge. Additionally, in the March 2022 NOPR, DOE identified the post-purge time threshold being increased to 30 seconds in the criterion for determining whether the “Optional Test Procedures for Conducting Furnaces and Boilers that have no OFF-Period Flue Loss” is applicable as a change in ANSI/ASHRAE 103-2017. DOE proposed to adopt the 30-second threshold in the newly proposed appendix EE, consistent with the change to ANSI/ASHRAE 103-2017. 87 FR 14622, 14628.

BWC stated that it appreciated DOE's inclusion of the change in post-purge time length to 30 seconds. (BWC, No. 19, p. 2-3)

Additionally, in the March 2022 NOPR, DOE proposed minor changes to the test method for models with post-purge times longer than 3 minutes, consistent with the updates included in ANSI/ASHRAE 103-2017. 87 FR 14622, 14631. Specifically, section 9.5.2.1 of ANSI/ASHRAE 103-2017 requires that for cases where the post-purge period is greater than 3 minutes, an additional measurement of the flue gas temperature during the cool-down test is required at the midpoint of the post-purge period. DOE proposed to adopt a harmonizing change in the newly proposed appendix EE. 87 FR 14622, 14631 and 14654.

DOE did not receive any comments regarding this proposal. For the reasons discussed in the March 2022 NOPR, DOE is finalizing this amendment to section 8.5(d) of appendix EE.

b. Calculations for Omission of Heat-Up and Cool-Down Tests

The current test procedure for consumer boilers allows certain units to omit the cool-down and heat-up tests. These include units that have been determined to have no measurable airflow through the combustion chamber and heat exchanger during the burner off-period and that have minimal post-purge periods (see section III.D.1.a of this document for discussion of post-purge time). For these boilers, the off-cycle losses are expected to be minimal. However, off-cycle losses (typically determined during the cool-down and heat-up tests) must be accounted for when determining the heating seasonal efficiency, Effy

. Section 8.10 of appendix N currently states, “In lieu of conducting the cool-down and heat-up tests, the tester may use the losses determined during the steady-state test described in section 9.1 of ASHRAE 103-1993 when calculating heating seasonal efficiency, Effy

.” Accordingly, sections 10.2 and 10.3 of appendix N provide the appropriate equations to use when calculating Effy

if the cool-down and heat-up tests are omitted per section 8.10 of appendix N. These equations are provided in sections 10.2 and 10.3 of appendix N because they were not included in ANSI/ASHRAE 103-1993.

As discussed in the March 2022 NOPR, ANSI/ASHRAE 103-2017 makes several updates to include these equations, and the equations in ANSI/ASHRAE 103-2017 are identical to those in appendix N. 87 FR 14622, 14629. Due to this harmonizing update, DOE proposed not to include these equations in the new appendix EE and to instead directly reference the relevant sections in ANSI/ASHRAE 103-2017 (11.3.11.3, 11.5.11.1, and 11.5.11.2). 87 FR 14622, 14631. DOE did not receive comment on this topic and is finalizing this amendment as proposed in the March 2022 NOPR.

c. Cycle Timings

ANSI/ASHRAE 103-2017 includes calculations, originally included in ANSI/ASHRAE 103-2007, for determining the average on-time and off-time per cycle for two-stage and modulating boilers, rather than assigning fixed values as in ANSI/ASHRAE 103-1993. DOE received comments in response to the May 2020 RFI generally indicating that these updated cycle timings are more representative. DOE referenced test data from the previous rulemaking to ascertain the potential impact of this update and tentatively determined that the new method would be more representative and not unduly burdensome and have minimal impact on AFUE ratings. 87 FR 14622, 14628. Therefore, DOE proposed to adopt the updated cycle times via adoption of the ASHRAE 103-2017 as the reference standard in the newly proposed appendix EE. 87 FR 14622, 14630.

In addition, DOE discussed that data collected for the January 2016 Final Rule

for three models of condensing, modulating boilers showed that the changes in on-cycle and off-cycle times resulted in changes in AFUE of 0.11, −0.50, and 0.22 percent, respectively. For two models of non-condensing, modulating boilers, calculating the AFUE based on the on-cycle and off-cycle times in ANSI/ASHRAE 103-2007 changed the AFUE by 0.11 and −0.14 percent, respectively. 87 FR 14622, 14630.

These data were presented at a public meeting for the March 11, 2015, NOPR pertaining to test procedures for furnaces and boilers and can be found at

www.regulations.gov/document/EERE-2012-BT-TP-0024-0021.

In response to the March 2022 NOPR, BWC stated that it agreed with DOE's conclusion that the new average use cycle calculations from ANSI/ASHRAE 103-2017 are more representative for modulating boilers and have little impact on efficiency ratings. (BWC, No. 19 at p. 4) The CA IOUs stated the ANSI/ASHRAE 103-2017 on/off time per cycle more accurately represents the typical operation for two-stage, modulating, and condensing boiler technologies. (CA IOUs, No. 20 at p. 1)

AHRI requested that DOE provide more data regarding the impacts of cycle timing on condensing models. (AHRI, No. 26 at p. 3)

In response to this request, DOE has conducted testing on two additional modulating condensing boilers to investigate the impact of the revised cycle timings on AFUE. Data collected from this testing is shown in Table III.1. For this investigation, DOE used the updated steady-state efficiency calculation method discussed in section III.E of this final rule for both the ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017 results such that the only variable influencing differences in AFUE ratings would be the cycle timings.

Table III.1—Impact of Cycle Timings on AFUE for Modulating Condensing Boilers

Model

ANSI/ASHRAE 103-1993

Cycle timings

(mm:ss)

AFUE

(percent)

ANSI/ASHRAE 103-2017

Cycle timings

(mm:ss)

AFUE

(percent)

Change in AFUE

(percent)

Unit No. 1

15:00 on/15:00 off

90.98

23:10 on/11:05 off

91.43

+0.45

Unit No. 2

15:00 on/15:00 off

91.61

20:29 on/11:50 off

91.46

−0.15

As indicated in Table III.1, the change in cycle timings resulted in insignificant changes to the AFUE values (+0.45 percent and −0.15 percent). These additional sample points are consistent with DOE's tentative determination that impacts to AFUE would be minimal as a result of the updated cycle timings in ANSI/ASHRAE 103-2017. Therefore, manufacturers would not be required to retest and rerate consumer boilers due to this change. Based on the discussion provided in the March 2022 NOPR, consideration of comments from interested parties, and this additional test data, DOE has determined that the updated approach in ANSI/ASHRAE 103-2017 increases the representativeness of the test procedure without being unduly burdensome.

During its testing of these two boilers, DOE recognized that the determination of cycle timings in Table 7 of ANSI/ASHRAE 103-2017 does not specify the precision to which these timings (t

and t

OFF

) should be calculated (

i.e.,

to the nearest minute or second). ANSI/ASHRAE 103-2017 provides no indication of whether these cycle timings can or should be rounded. Acknowledging that many testing facilities may only be able to time the burner cycling operation of the boiler under test to the nearest second, DOE is providing additional specification in appendix EE to require that calculated cycle timings shall be rounded to the nearest second. This clarification is not expected to impact results significantly but serves to improve repeatability and reproducibility of test results by clarifying the duration of the cycle time.

d. Oversize Factor

The oversize factor for a boiler indicates the ratio between the boiler's nominal capacity and the home's heating load. This factor is represented by the symbol “α” and is determined in sections 11.2.8.3 and 11.4.8.3 of ANSI/ASHRAE 103-1993 and sections 11.2.8.2 and 11.4.8.2 of ANSI/ASHRAE 103-2017.

ANSI/ASHRAE 103-2017 updates the method for calculating the oversize factor. While the oversize factor was calculated from a lookup table based on design heating requirement (“DHR”) in ANSI/ASHRAE 103-1993, ANSI/ASHRAE 103-2017 assigns a constant value of 0.70 to α to represent the national average oversize factor. Based on DOE's assessment of its test data, DOE stated in the March 2022 NOPR that this change would be unlikely to have a substantive impact on AFUE ratings because the calculations are not particularly sensitive to changes in the oversize factor value. Specifically, DOE reviewed test data for three modulating, condensing boilers and found that the change in oversize factor from a calculated value, as specified in ANSI/ASHRAE 103-1993, to 0.7 changed the AFUE rating by 0.01 AFUE percentage points or less for all 3 models. 87 FR 14622, 14629. In the March 2022 NOPR, DOE proposed to adopt the constant 0.7 oversize factor through incorporation by reference of ANSI/ASHRAE 103-2017.

Id.

BWC supported DOE's proposal to adopt the constant 0.7 oversize factor through incorporation of ANSI/ASHRAE 103-2017. BWC's analysis of this proposal demonstrated that adopting this approach would not have a significant impact on overall product efficiency. (BWC, No. 19 at p. 3)

Busse stated that the oversize factor should be a constant value less than 0.4

based on an Air Conditioning Contractors of America (“ACCA”) equipment selection checklist

indicating to installers that the selected equipment should be less than or equal to 140 percent of the designed total heating load. Busse commented that in the last 40 years, it has become apparent that oversized equipment is less efficient, such that a more appropriate oversize factor of approximately 0.35 is justified. (Busse, No. 22 at p. 6-7)

ACCA “Verifying ACCA Manual S® Procedures” brochure,

www.acca.org/HigherLogic/System/DownloadDocumentFile.ashx?DocumentFileKey=2f0a6828-2205-e112-745f-7215c9a85541&forceDialog=0.

Last accessed October 7, 2022.

In response, DOE notes that commenters did not provide field statistics that would help to determine what a national average representative oversize factor would be, nor is DOE aware of any such data. While contractors may be oversizing boilers to a lesser degree today than in the past, DOE expects that many replacements will be made on a like-for-like basis such that the input capacity of the replacement boiler will match that of the previous boiler (and thus maintain the same oversize factor as the previous boiler). Without sufficient nationally representative data to support deviation from the industry-accepted oversize factor specified in ANSI/ASHRAE 103-2017, DOE is adopting the provision to use a constant oversize factor of 0.70 through incorporation by reference of ANSI/ASHRAE 103-2017. In addition, as discussed previously in this document and initially discussed in the March 2022 NOPR, based on a review of its test data DOE has determined that this change would not substantively impact on AFUE.

e. Annual Performance Metrics

ANSI/ASHRAE 103-2017 changes the method for determining national average burner operating hours (“BOH”), average annual fuel energy consumption (“E

”), and average annual auxiliary electrical energy consumption (“E

”),

especially for two-stage and modulating products, based on a 2002 study from NIST.

A typographical correction to the determination of E

at 10 CFR 430.23(n) is discussed in section III.F.5 of this final rule.

The CA IOUs stated that ASHRAE 103-2017 utilizes differentiating calculations for annual operating hours and reduced fuel input rates that reflect real-world operation conditions of boilers that more accurately represents the typical operation for two-stage, modulating, and condensing boilers that spend a significant amount of time operating at part-load conditions. (CA IOUs, No. 20 at p. 1)

These additional annual performance metrics are not required for representations or certifications to DOE at this time. Federal Trade Commission product labeling requirements at 16 CFR 305.8 specify that determinations of estimated annual energy consumption, estimated annual operating cost, and energy efficiency rating must be determined in accordance with the testing and sampling provisions required by DOE as set forth in subpart B of 10 CFR part 430. For boilers, the product labeling provisions are specified at 16 CFR 305.20(f) and currently only require AFUE to be presented. Thus, manufacturers are not required to report BOH, E

, or E

for consumer boilers as of this final rule. However, manufacturers may voluntarily represent these values. To ensure that any voluntary representations of these values are conducted in accordance with the DOE test procedure, DOE is adopting the revised calculation methods in ANSI/ASHRAE 103-2017 for BOH, E

, and E

f. Measurement of Relative Humidity

The current DOE test procedure at appendix N, through incorporation by reference of ANSI/ASHRAE 103-1993, specifies limitations on the relative humidity of the ambient air of the test chamber when testing a condensing boiler. Sections 9.2 and 9.8.1 of ANSI/ASHRAE 103-1993 state, “The humidity of the room air shall at no time exceed 80 percent” but do not provide instruction on the instrumentation necessary to measure the relative humidity. ANSI/ASHRAE 103-2017 provides new requirements in section 8.5.1 to follow ANSI/ASHRAE 41.6-2014 in order to measure relative humidity for testing condensing boilers. Because the DOE test method and ANSI/ASHRAE 103-1993 currently limit relative humidity allowed during testing, DOE reasoned in the March 2022 NOPR that relative humidity already must be measured under the current procedure; thus, DOE tentatively concluded that the method prescribed by ANSI/ASHRAE 103-2017 would likely be similar to current practices and requested comment on this topic. 87 FR 14622, 14636-14637.

Busse suggested that DOE should verify that ANSI/ASHRAE 41.6-2014 includes precision and calibration requirements. (Busse, No. 22 at p. 9-10) DOE has reviewed ANSI/ASHRAE 41.6-2014 in detail and notes that it provides setup and calibration methods for both psychrometers and hygrometers (two types of instruments which can be used to measure relative humidity). Section 6 of ANSI/ASHRAE 41.6-2014 provides calibration requirements, and sections 7 and 8 of ANSI/ASHRAE 41.6-2014 provide measurement methods, precision requirements, and measurement uncertainty analysis.

As discussed further in section III.K of this document, DOE received comments indicating that introducing these new requirements for measurement and instrumentation would not be unduly burdensome to industry. In this final rule, DOE is incorporating by reference ANSI/ASHRAE 41.6-2014 in appendix EE for the purpose of performing the required humidity measurement.

2. IEC 62301 and ASTM D2156-09

DOE noted in the May 2020 RFI that the version of IEC 62301 currently incorporated by reference in appendix N is still the most recent version, and the most recent iteration of ASTM D2156-09 is a version reapproved in 2018 that did not contain any changes from the 2009 version. 85 FR 29352, 29355. DOE did not receive any comments pertaining to its incorporation by reference of IEC 62301 or ASTM D2156-09 and in the March 2022 NOPR proposed to maintain the current reference to IEC 62301, and to update the reference to ASTM D2156-09 to reflect the version that was reapproved in 2018. 87 FR 14622, 14628. DOE did not receive any comments related to its incorporation by reference of these standards. In this final rule, DOE is finalizing their adoption for appendix EE as proposed.

E. Steady-State Efficiency for Condensing Modulating Boilers

In the May 2020 RFI and the March 2022 NOPR, DOE discussed that ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017 yield a circular reference when calculating the steady-state efficiency for condensing modulating boilers. 85 FR 29352, 29357; 87 FR 14622, 14629.

As discussed in the March 2022 NOPR, the circular reference arises within the calculation of steady-state efficiencies at maximum and minimum input rate, which depends in part on the steady-state heat loss due to condensate going down the drain at the maximum and reduced input rates. (

See

section 11.5.7.3 of ANSI/ASHRAE 103-2017, which refers to section 11.3.7.3.) The steady-state heat loss due to condensate going down the drain at the maximum and minimum input rates is calculated in part based on the national average outdoor air temperature at the maximum and minimum input rates.

(

See

section 11.5.7.2 of ANSI/ASHRAE 103-2017, which refers to section 11.3.7.2.) The national average outdoor air temperatures at the maximum and minimum input rates are both a function of the balance point temperature. (

See

section 11.5.8.3 of ANSI/ASHRAE 103-2017, which refers to section 11.4.8.3.) The balance point temperature is calculated based on the oversize factor at maximum input rate (which is, as discussed previously, a constant value in ANSI/ASHRAE 103-2017) and the ratio of the heating capacity at the minimum input rate to the heating capacity at the maximum input rate. (

See

section 11.5.8.4 of ANSI/ASHRAE 103-2017, which references section 11.4.8.4.) The heating capacities at the minimum and maximum input rates are calculated based in part on the steady-state efficiencies at minimum and maximum input rates, respectively. (

See

section 11.5.8.1 of ANSI/ASHRAE 103-2017, which references section 11.4.8.1.) If the calculations were interpreted to refer back to the steady-state efficiencies at minimum and maximum input rates for a modulating, condensing model, as determined by section 11.5.7.2 of ANSI/ASHRAE 103-2017, a circular reference would result.

However, since there is no specific instruction to use the values as calculated by section 11.5.7.2, DOE stated in the March 2022 NOPR that it interprets ANSI/ASHRAE 103-2017 to instruct that the steady-state efficiency at maximum and reduced input rates be determined as specified in section 11.4.8.1, which refers to section 11.4.7, which in turn refers to section 11.2.7 for the calculation of steady-state efficiency for non-condensing, non-modulating boilers. 87 FR 14622, 14629. The steady-state efficiencies at maximum and minimum input calculated using section 11.2.7 can then be used to obtain values for output capacities at the maximum and reduced input, which are needed to calculate the balance point temperature, the average outdoor air temperature at maximum and minimum input, and finally the heat loss due to condensate going down the drain at maximum and minimum input rates.

Id.

In the March 2022 NOPR, DOE proposed to add provisions to clarify the approach for calculating steady-state efficiencies at maximum and minimum input rates for condensing, modulating boilers using ANSI/ASHRAE 103-2017. 87 FR 14622, 14629. Specifically, DOE proposed to codify provisions in section 10.1.2 of appendix EE to explain how to calculate these values without a circular reference, ultimately by referring back to section 11.2.7 of ANSI/ASHRAE 103-2017. 87 FR 14622, 14655.

Crown, U.S. Boiler, BWC, Rheem, A.O. Smith, AHRI, and AGA & APGA all supported DOE's proposal to provide additional specification that would avoid a circular reference in the test procedure. (A.O. Smith, No. 24 at p. 3; AGA & APGA, No. 25 at p. 2) Rheem recommended that each subsection in section 10.1.2 of appendix EE should not say “previous step” but should refer to the appropriate subsection. Specifically, Rheem recommended that DOE present an equation for balance point temperature, T

, in which the variables used in the equation reference the relevant sections in ANSI/ASHRAE 103-2017. (Rheem, No. 18 at p. 3) Crown, U.S. Boiler, BWC, and AHRI all recommended the same revision for section 10.1.2 to improve the clarity of the section. (Crown, No. 16 at p. 3; U.S. Boiler, No. 17 at p. 2-3; BWC, No. 19 at p. 3; AHRI, No. 26 at p. 2-3) Specifically, the commenters recommended revising section 10.1.2 to replace the output capacity parameters Q

OUT,R

and Q

OUT

as follows:

10.1.2 Calculate the balance point temperature (T

) for condensing, modulating boilers by using the following equation in place of that referenced by 11.5.8.4 [of ANSI/ASHRAE 103-2017]:

ER13MR23.000

Where:

= typical average outdoor temperature at which a boiler starts operating, 65 °F

OA,T

= the typical outdoor design temperature, 5 °F

α = oversize factor, as defined in 11.4.8.2 [of ANSI/ASHRAE 103-2017]

= steady-state nameplate maximum fuel input rate

IN,R

= steady-state reduced input fuel input rate

S,SSR

= average sensible heat loss at steady state, reduced input operation

S,SS

= average sensible heat loss at steady state, maximum input operation

In reviewing this equation, DOE agrees that the recommended equation adequately resolves the circular reference issue in the same manner as DOE proposed in the March 2022 NOPR, but with a simplified approach to specifying the correct calculations for determining the steady-state efficiency for condensing modulating boilers. Rather than determining Q

OUT

and Q

OUT,R

based on the steady-state efficiencies Effy

and Effy

SS,R

(using section 11.2.7 of ANSI/ASHRAE 103-2017) to calculate T

, the suggested equation simply inserts the appropriate variables directly into the equation for T

, providing the same result. DOE is therefore adopting this revised equation in section 10.1.3 of appendix EE.

F. Corrections and Clarifications

1. Off-Cycle Losses

In response to the March 2022 NOPR, several commenters indicated that ANSI/ASHRAE 103-2017 has a typographical error in the equations used to determine L

I,OFF1

and L

S,OFF1

(off-cycle infiltration and sensible losses, respectively). Specifically, Crown and U.S. Boiler stated there is an error in section 11.2.10.8 of ANSI/ASHRAE 103-2017 for the calculation of L

I,OFF1

. Crown and U.S. Boiler stated that the equation for L

I,OFF1

in ANSI/ASHRAE 103-1993 was erroneous because Q

was multiplied by 60 when it should have been divided by 60. According to Crown and U.S. Boiler, ASHRAE attempted to correct this error in ANSI/ASHRAE 103-2007, but inadvertently copied the equation for L

S,OFF1

to L

I,OFF1

for units having post-purge times below 3 minutes, and this error was not corrected in the 2017 edition. (Crown, No. 16 at p. 3; U.S. Boiler, No. 17 at p. 3) Similarly, Rheem identified this issue involving the factor of 60 in the equations for L

S,OFF1

and L

I,OFF1

and asked DOE to evaluate the impact on ratings. (Rheem, No. 18, p. 6)

DOE has examined the equations for L

S,OFF1

and L

I,OFF1

in ANSI/ASHRAE 103-2017 and understands that the factor of 60 is used to convert the cycle times (reported in minutes) into hours because the input rate is expressed in terms of Btu/h. Thus, the cycle times must be divided by 60 to convert these values into hours. Section 11.2.10.6 of ANSI/ASHRAE 103-2017 performs this operation correctly for determining L

S,OFF1

, but the factor of 60 is used incorrectly in sections 11.2.10.6 and 11.2.10.8 of ANSI/ASHRAE 103-1993.

As Crown and U.S. Boiler indicated, industry has been aware of this error

since the development of ANSI/ASHRAE 103-2007. As such, DOE expects that current ratings are determined based on the corrected use of the factor of 60. In particular, DOE is aware that the Gas Appliance Manufacturers Association (GAMA)

developed a computer program to calculate AFUE.

DOE has reviewed a version of this program (dated October 15, 2003) and determined this calculation was corrected in the underlying code. Based on this finding, correcting the use of the factor of 60 (by incorporating by reference ANSI/ASHRAE 103-2017) should not affect the ratings of products which have already been tested and certified. Furthermore, these calculations apply only to consumer boilers that have system numbers 2, 3, or 4 with post-purge times greater than 30 seconds, which DOE understands to be a relatively low fraction of the market based on its own compliance testing.

GAMA and the Air-Conditioning and Refrigeration Institute (ARI) merged in 2008 to form AHRI.

In the May 2020 RFI, DOE discussed the industry-developed computer program that calculates AFUE based on ANSI/ASHRAE 103-1993 “AFUE v1.2.” This software was most recently updated in April 2004. 85 FR 29352, 29356.

DOE notes that section 11.2.10.8 of ANSI/ASHRAE 103-1993 provided the correct equation for L

I,OFF1

for models with post-purge periods that are less than or equal to 3 minutes (albeit with the aforementioned error with the factor of 60).

The equation for L

I,OFF1

for models with post-purge periods that are greater than to 3 minutes is corrected in ANSI/ASHRAE 103-2017 and is adopted in this final rule through incorporation by reference.

2. Conversion Factor for British Thermal Units

In the March 2022 NOPR, DOE noted inconsistencies in the conversion factors from watts (W) or kilowatts (kW) to British thermal units per hour (Btu/h), in which some sections used a conversion factor of 3.412 and other sections use 3.413. 87 FR 14622, 14634. DOE stated that the conversion factor between watts and Btu/h is generally accepted to be 1 watt = 3.412142 Btu/h (or 1 Btu/h = 0.2930711 watts), as published in the

2021 ASHRAE Handbook—Fundamentals.

Id.

This value is more appropriately rounded to 3.412 W/(Btu/h); therefore, DOE proposed correcting the test procedures to use 3.412 W/(Btu/h) in all calculations where 3.413 W/(Btu/h) was previously used.

Id.

DOE stated in the March 2022 NOPR that it did not expect this correction to affect AFUE ratings.

Id.

2021 ASHRAE Handbook—Fundamentals (I-P Edition).

Peachtree Corners, GA: American Society of Heating, Refrigeration and Air-Conditioning Engineers, 2021. Available at

www.ashrae.org/technical-resources/ashrae-handbook/description-2021-ashrae-handbook-fundamentals.

DOE did not receive comments on this topic. For the reasons discussed here and in the March 2022 NOPR, this final rule implements a conversion factor of 3.412 in each instance within new appendix EE. DOE also amends appendix N—which will remain applicable to consumer furnaces other than boilers—to use the corrected conversion factor.

3. Oil Pressure Instrumentation Error

Section 6.3 of ANSI/ASHRAE 103-2017 states, “Instruments for measuring gas, oil, air, water, and steam pressure shall be calibrated so that the error is no greater than the following.” However, the specifications that follow omit the instrumentation requirements applicable to measuring oil pressure. Section 6.3(b) of ANSI/ASHRAE 103-1993 included the oil pressure specification.

In response to the March 2022 NOPR, Rheem commented that DOE should add the oil pressure instrumentation specification from ANSI/ASHRAE 103-1993 to section 5 of the new appendix EE test procedure. (Rheem, No. 18 at p. 6)

This final rule reinstates the omitted provisions from section 6.3 of ANSI/ASHRAE 103-1993 in section 5 of appendix EE.

4. Gas Inlet Conditions

Section 7.1 of appendix N references Table 1 of ANSI/ASHRAE 103-1993 for maintaining the gas supply, ahead of all controls for a furnace,

at an acceptable test pressure. The natural gas inlet pressure shall be between the “normal” and “increased” values shown in Table 1 of ANSI/ASHRAE 103-1993. Table 1 in ANSI/ASHRAE 103-2017 provides identical gas inlet pressures to those in ANSI/ASHRAE 103-1993 (this table is presented in section 8.2.1.3 of ASHRAE 103-2017, which is excluded from reference in the current appendix N test procedure). Table 1 also specifies the specific gravity of the test gases. The pressures and specific gravity of the test gases are reproduced in Table III.2 of this document.

This term refers to the broader definition of “furnace,” which includes warm air furnaces and boilers.

Table III.2—Natural Gas Inlet Pressures and Specific Gravity of Test Gases in Table 1 of ANSI/ASHRAE 103-1993 and ANSI/ASHRAE 103-2017

Type

Test pressure

(inches water column)

Normal

Increased

Specific

gravity

(air = 1.0)

Natural

7.0

10.50

.65

Manufactured

3.5

5.25

.38

Butane

11.0

13.00

2.00

Propane

11.0

13.00

1.53

In response to the March 2022 NOPR, Crown and U.S. Boiler stated that the gas inlet pressure requirements in section 8.2.1.3 of ANSI/ASHRAE 103-2017 are appropriate and necessary for units with pilot lights because most pilots have no pressure regulation within the appliance itself, and thus the input rate of the pilot is determined in large part by the inlet pressure. Crown and U.S. Boiler noted, however, that since continuous standing pilots are prohibited by EPCA on consumer boilers, such restrictive requirements on the gas inlet pressure are no longer necessary in the Federal test procedure and may place undue burden on test labs. Crown and U.S. Boiler commented that maintaining a 7.0 inches water column (“in. w.c.”) minimum inlet pressure is not always possible in some test labs, nor is it necessary as long as the regulator outlet pressure can be maintained, and the nameplate input

achieved. Crown and U.S. Boiler further indicated that expensive gas booster equipment may be necessary to meet the 7.0 in. w.c. minimum. Crown and U.S. Boiler stated that gas appliances are generally listed for use up to 14.0 in. w.c. inlet pressure, so there is also no reason to reduce this pressure to 10.5 in. w.c. on a boiler without a continuous pilot in order to provide results that are repeatable and representative of what can be expected in the field. In order to afford labs greater flexibility while still preventing boilers from being tested at gas inlet pressures for which they are not intended to be used in the field, Crown and U.S. Boiler suggested replacing the second sentence of section 8.2.1.3 of ANSI/ASHRAE 103-2017 with: “The gas supply, ahead of all controls for a furnace, shall be maintained at a test pressure within the upper and lower limits shown in the manufacturer's instructions or on the boiler itself. In the absence of any such limits, the gas supply pressure shall be maintained between the normal and increased values shown in Table 1 of ANSI/ASHRAE 103-2017.” (Crown, No. 16 at p. 2-3; U.S. Boiler, No. 17 at p. 2)

Busse urged DOE to modify the language in section 7.1 of appendix EE to include the term “approximately” when referring to meeting the specific gravity requirements in Table 1 of ANSI/ASHRAE 103-2017, asserting that the omission of this term suggests that DOE expects the specific gravity to be exactly as shown in Table 1 without providing instrument requirements for measuring. (Busse, No. 22 at p. 10)

At 42 U.S.C. 6295(f)(3)(A), EPCA mandates that gas-fired boilers manufactured on or after September 1, 2012, must not have a constant burning pilot. DOE agrees that the test procedure requirements in appendix N (which reference Table 1 of ANSI/ASHRAE 103-1993) have a greater contribution to maintaining the reproducibility and repeatability of test results for consumer boilers with constant burning pilots; however, it is currently unclear to DOE what the impacts of updating the natural gas inlet pressure requirements as suggested would be on measured efficiency ratings for boilers without constant burning pilots. Crown and U.S. Boiler did not provide data to indicate that their suggested approach of relying on the manufacturer's instructions for setting natural gas inlet pressure will not significantly impact ratings. Manufacturers have not previously expressed concern regarding the ability to meet the inlet pressure requirements in appendix N, and no waivers have been received for consumer boilers that are not compatible with the inlet pressure provisions. This suggests that manufacturers and test laboratories have been able to meet these setup requirements since compliance with the currently applicable appendix N test procedure has been required (July 13, 2016).

For these reasons, DOE has determined that no correction to the natural gas inlet pressure requirements is necessary at this time and is adopting the reference to Table 1 of ANSI/ASHRAE 103-2017 in section 7.1 of appendix EE as proposed in the March 2022 NOPR. Regarding Busse's suggestion to include the word “approximately” in reference to the specific gravity values referenced in section 7.1, DOE agrees that the specific gravity may not be exactly as provided in Table 1 of ANSI/ASHRAE 103-2017 because variations exist due to differences in gas composition in supply sources. DOE understands that the purpose of specifying the gas characteristics in Table 1 of ANSI/ASHRAE 103-2017 is to ensure that the energy content in the gas is consistent for the repeatability and reproducibility of the test. DOE notes that explicit tolerances are provided for the higher heating value of the gas used, such that providing explicit tolerances for the specific gravity of the gas would be redundant. As such, DOE is adopting Busse's suggestion to state that the specific gravity of the gas should be “approximately” that shown in Table 1 of ANSI/ASHRAE 103-2017.

5. Active Mode Electrical Energy Consumption

As previously discussed, AFUE does not include active mode electrical consumption for gas-fired and oil-fired boilers. Instead, the DOE test procedure includes provisions for determining the average annual auxiliary electrical energy consumption for gas-fired and oil-fired boilers (E

), as a separate metric from AFUE, that accounts for active mode, standby mode, and off mode electrical consumption. (See appendix N, section 10.4.3.) E

is referenced by the calculations at 10 CFR 430.23(n)(1) for determining the estimated annual operating cost for furnaces. However, the provisions at 10 CFR 430.23(n) include several incorrect references to sections in appendix N. In the March 2022 NOPR, DOE proposed to correct 10 CFR 430.23(n)(1) to reference the appropriate sections of appendix N where the currently codified provisions point to the wrong sections. Additionally, DOE proposed to revise 10 CFR 430.23(n)(1) such that sections in appendix N are referenced for furnaces and sections in appendix EE are referenced for boilers. 87 FR 14622, 14633, and 14643.

DOE did not receive any comments on this topic. In this final rule, DOE adopts these corrections as proposed.

6. Circulator Pumps

Section 8.2 of the proposed appendix EE from the March 2022 NOPR included instructions on the electrical energy consumption measurements for various boiler components in order to calculate PE, the electrical power involved in burner operation. 87 FR 14622, 14654. It stated that the measurement of PE must include the boiler pump if so equipped.

Id.

In response to the March 2022 NOPR, Rheem noted that section 2 of the proposed appendix EE defines a “boiler pump”

as being separate from the circulating water pump; however, the term “circulating water pump” is not defined in the proposed appendix EE or ANSI/ASHRAE 103-2017. Rheem recommended that DOE add a definition for “circulating water pump” to clarify the difference between these pumps and to reduce confusion when performing the procedure in section 8.2 of appendix EE, which refers to both pump types. (Rheem, No. 18 at p. 5-6)

Section 2.2 of appendix N defines a “boiler pump” as a pump installed on a boiler that is separate from the circulating water pump.

DOE notes that the definition for “boiler pump” was established in the January 2016 Test Procedure Final Rule. 81 FR 2628, 2647. In the January 2016 Test Procedure Final Rule, in describing devices that use power during the active mode, DOE discussed a secondary pump for boilers (

i.e.,

boiler pump) used to maintain a minimum flow rate through the boiler heat exchanger, which is most typically associated with condensing boiler designs.

Id.

at 81 FR 2633. In the preamble to the January 2016 Test Procedure Final Rule, DOE stated that it would define a boiler pump as, “a pump installed on a boiler that maintains adequate water flow through the boiler heat exchanger and that is separate from the circulating water pump;” however, this definition was not codified with the additional clarification that the boiler pump maintains adequate water flow through the heat exchanger.

Id.

at 81 FR 2634. In order to improve the clarity of the boiler pump definition, DOE is revising this definition to reflect the language which was inadvertently omitted from the January 2016 Test Procedure Final Rule.

Additionally, section 9.1.2.2 of ANSI/ASHRAE 103-2017 states that, for hot water boilers, the circulating water

pump nameplate power is to be used to determine the electrical power to the circulating water pump (BE), and if the pump nameplate power is not available, use the pump power listed in the water pump manufacturer's literature or use 0.13 kW. In response to the March 2022 NOPR, Busse suggested that, because circulator pumps do not have a “nameplate” power value, the water pump manufacturer's literature could be used instead for calculating the value of BE. Busse also commented that the default value of 0.13 kW in ANSI/ASHRAE 103-2017 may not be appropriate for modern electronically commutated motor-based circulator pumps. (Busse, No. 22 at p. 11)

At this time, DOE does not have sufficient data on circulating water pumps used with consumer hot water boilers to specify a more representative power draw to be used in lieu of manufacturer-reported information (either on a nameplate or in the I&O manual). As ANSI/ASHRAE 103-2017 is currently the industry-accepted test standard

for consumer boilers, DOE expects that the provisions for circulator pump power remain representative for current installations. Additionally, DOE notes that the value of BE is not a factor that determines AFUE (see section III.C for discussion about the AFUE metric).

ANSI/ASHRAE 103-2022 does not provide substantive updates to provisions for circulator pump power.

7. Units With Draft Hoods or Draft Diverters

Section 6.4 of appendix N provides installation instructions for units with draft hoods or draft diverters. Among other requirements, this section specifies installing the stack damper in accordance with the “I&O manual.”

In response to the March 2022 NOPR, Rheem commented that section 6.4 of appendix N appeared to have been omitted from the proposed appendix EE. Rheem noted that these provisions are still relevant to boilers and should be carried over into the new appendix EE test procedure. (Rheem, No. 18 at p. 6)

The March 2022 NOPR proposed in section 6 (“Apparatus”) of appendix EE to reference section 7 of ANSI/ASHRAE 103-2017 (“Apparatus”) including sections 7.2.3.1 and 7.3.3.1. Section 7.3.3.1 of ANSI/ASHRAE 103-2017 specifies stack and flue installation requirements for boilers with draft hoods or draft diverters by referencing section 7.2.3.1 of ANSI/ASHRAE 103-2017. The language in section 7.2.3.1 of ANSI/ASHRAE 103-2017 is identical to the provisions in section 6.4 of the current appendix N, except that section 7.2.3.1 specifies that the stack damper be installed in accordance with the “manufacturer's instructions” rather than the “I&O manual” specified in section 6.4. DOE's proposal to reference sections 7.2.3.1 and 7.3.3.1 of ANSI/ASHRAE 103-2017 through reference to section 7 in the new appendix EE test procedure maintained the installation instructions for units with draft hoods or draft diverters in appendix EE. This final rule maintains the reference to section 7 of ANSI/ASHRAE 103-2017 in section 6 of appendix EE.

DOE has determined, however, that maintaining the more specific reference to the manufacturer's I&O manual, rather than a general reference to manufacturer's instructions, will ensure the reproducibility of the test procedure by providing a more specific reference to the document that must be consulted with regard to installing the stack damper. Therefore, this final rule adds an exception in section 6 of appendix EE to specify referencing the I&O manual in lieu of manufacturer's instructions in section 7.2.3.1 of ANSI/ASHRAE 103-2017.

8. Rounding of AFUE

In response to the March 2022 NOPR, Busse observed an inconsistency between requirements to round the AFUE at 10 CFR 430.23(n)(2)(iii) and requirements to truncate the AFUE at 10 CFR 429.18(a)(2)(vii). (Busse, No. 22 at p. 11)

On July 22, 2022, DOE published a final rule regarding certification requirements for several covered products and equipment, including consumer boilers (“July 2022 Certification Final Rule”). 87 FR 43952. In an amendment established by that final rule, effective August 22, 2022, DOE modified 10 CFR 429.18(a)(2)(vii) to state that AFUE must be rounded to the nearest one-tenth of a percentage point.

Id.

at 87 FR 43968. As this amendment provides consistency between the certification requirement and the test procedure, no further correction is required in this rulemaking.

G. Other Test Procedure Topics

In the course of this rulemaking, DOE solicited feedback on additional aspects of the current test procedure for consumer boilers to assess whether they remain representative of the energy consumption during an average use cycle. DOE did not propose to amend the test procedure for consumer boilers with regard to these topics in the March 2022 NOPR, and after consideration of comments received in response to that NOPR, DOE determined not to amend the test procedure accordingly. Comments received with regard to these topics are discussed in the following subsections.

1. Outdoor Design Temperature

ANSI/ASHRAE 103-2017 assigns a value of 5 °F for the typical outdoor design temperature and 42 °F for the average outdoor air temperature, represented by T

OA,T

and T

, respectively. The outdoor design temperature is the lowest expected temperature at which the boiler can satisfy the home's heating demand, while the average outdoor air temperature is the average temperature during the heating season.

In response to the March 2022 NOPR, Busse stated that the 5 °F outdoor design temperature used in ANSI/ASHRAE 103-1993

may be out of date due to climate change and suggested that different outdoor design temperatures could be assigned for furnaces and boilers. (Busse, No. 22 at p. 4) Similarly, Busse indicated that a 42 °F average outdoor air temperature may no longer be valid based on recent climate change data. (Busse, No. 22 at p. 11)

DOE notes that the same requirement is also specified in ANSI/ASHRAE 103-2017.

In response, DOE notes that homes in the United States—particularly in the Northeast region, where most boilers are installed—still experience temperatures as low as 5 °F during the heating season

despite climate change trends. DOE does not have any data, nor did Busse or other commenters provide any such data, suggesting a value other than 5 °F that would provide more representative test results. As such, DOE is maintaining 5 °F as the outdoor design temperature in the appendix EE test procedure for consumer boilers.

For example, daily temperature data for the Albany, NY, area for the winter of 2022 (December 1, 2021, through March 1, 2022) shows 13 days during which the observed temperature reached at or below 5 °F. The Duluth, MN, area experienced 55 days during which the observed temperature reached at or below 5 °F during the same time period. Data for these areas are available at

www.weather.gov/wrh/Climate?wfo=aly

and

www.weather.gov/wrh/Climate?wfo=dlh.

Last accessed October 7, 2022.

Regarding the average outdoor air temperature, DOE examined average outdoor air temperatures for the contiguous United States during the months of October, November, December, January, February, and March (

i.e.,

the months during which consumer boilers would be expected to operate).

This data indicates that from

2012 through 2022, average outdoor air temperatures during these months is 41 °F, which aligns closely with the value of 42 °F specified in ANSI/ASHRAE 103-2017. Therefore, in this final rule, DOE is maintaining the value of 42 °F for T

as specified by ANSI/ASHRAE 103-2017.

These temperatures are published by the National Oceanic and Atmospheric Administration and are available at

www.ncei.noaa.gov/access/

monitoring/climate-at-a-glance/national/time-series.

Last accessed October 7, 2022.

2. Ambient Conditions

The current test procedure for consumer boilers in appendix N, through incorporation by reference of ANSI/ASHRAE 103-1993, specifies that the ambient air temperature during testing must be between 65 °F and 100 °F for non-condensing boilers, and between 65 °F and 85 °F for condensing boilers (see section 7 of appendix N and section 8.5.2 of ANSI/ASHRAE 103-1993). In addition, the relative humidity cannot exceed 80 percent during condensate measurement (see section 8 of appendix N and section 9.2 of ANSI/ASHRAE 103-1993).

In the May 2020 RFI, DOE requested comment and data on the effects of ambient temperature and relative humidity on AFUE results, whether the current ranges of allowable conditions adversely impact the representativeness of AFUE values or repeatability of AFUE testing, and whether a narrower range of allowable ambient conditions would increase testing burden. 85 FR 29352, 29356.

As discussed in the March 2022 NOPR, DOE received comments from AHRI and manufacturers supporting the current range of allowable operating conditions, while the CA IOUs and NEEA suggested limiting this range to reflect the temperatures of spaces where boilers may be installed. 87 FR 14622, 14631.

DOE investigated concerns regarding the ambient conditions as part of the January 2016 Final Rule (

see

81 FR 2628, 2638; Jan. 15, 2016). Testing conducted in support of the January 2016 Final Rule indicated there was no definitive impact of variation of ambient conditions on the resultant AFUE, and DOE determined there was not adequate data to justify changing the test procedure to narrow the ranges. In the March 2022 NOPR, DOE provided a similar tentative determination based on the lack of sufficient evidence, and thus did not propose any changes at that time. 87 FR 14622, 14631-14632.

In response, while the CA IOUs supported incorporation by reference of ANSI/ASHRAE 103-2017, they encouraged DOE to reexamine the impacts of ambient conditions on AFUE ratings by conducting additional testing. (CA IOUs, No. 20 at p. 2) NYSERDA requested that DOE revise the test procedure to ensure that condensing and non-condensing boilers are tested under the same ambient conditions to allow consumers to make informed decisions between these products. NYSERDA also requested that DOE review the impacts of ambient temperature on boiler performance and review the jacket loss assumptions based on likely real-world operating conditions. Citing that DOE has not provided a further study on ambient conditions since the 2016 rulemaking, NYSERDA urged DOE to revisit the issue of ambient temperature impacts on consumer boiler performance and conduct additional analysis and/or testing either as part of the current rulemaking or in anticipation of the next statutorily mandated review. (NYSERDA, No. 23 at p. 5)

The Joint Advocates stated they did not believe that separate ambient conditions are necessary for non-condensing and condensing boilers, and that the range of allowable ambient temperatures is too broad to accurately measure energy use during a representative average use cycle. The Joint Advocates cited course material from Continuing Education and Development, Inc. indicating that a variation in ambient temperature of 20 °F can affect the thermal efficiency of a commercial package boiler by over 0.5 percent, and therefore suggested that DOE require the ambient temperature to be maintained between 65 °F and 85 °F for all consumer boilers. (Joint Advocates, No. 21 at p. 3)

Busse stated that a boiler tested at the current temperature and humidity limits should perform at a higher AFUE than when tested at a “normal” lab condition of 70 °F and 50 percent relative humidity due to higher water vapor content and higher dew point temperature and thus recommended limiting the test room conditions to 75 °F and 55 percent relative humidity. Busse noted that the National Bureau of Standards Information Report (“NBSIR”) recommended limits on the original test room conditions,

and that water vapor content and dew point temperature vary significantly with temperature (specifically providing information at 42 °F [average outdoor air temperature], 70 °F [“normal” lab condition], and 85 °F [maximum allowable during AFUE test]). Busse also cited Burnham Holdings, Inc. (“BHI”) test data for a single condensing boiler which showed a change in AFUE of 1.3 percent when the relative humidity was changed from approximately 30 percent to 70 percent. (Busse, No. 22 at p. 5)

Busse's comment references two reports from National Bureau of Information: NBSIR 78-1543: “Recommended Testing and Calculation Procedures for Determining the Seasonal Performance of Residential Central Furnaces and Boilers” (September 1978) and NBSIR 80-2110, “Recommended Testing and Calculation Procedures for Estimating the Seasonal Performance of Residential Condensing Furnaces and Boilers” (April 1981).

DOE notes the data collected thus far has been on a limited sample of boilers, and the information required to amend the ambient conditions should reflect the array of boiler designs on the market. The impact of the ambient air conditions would vary based on how the ambient air interacts with the boiler during its normal operation. As noted previously, in the January 2016 NOPR, DOE concluded that the test data was not definitive enough to provide justification for changing the ambient conditions. Regarding the data submitted by Busse, DOE notes that BHI also provided that data point in a comment responding to the May 2020 RFI (BHI, No. 11 at p. 2, 11). As discussed in the March 2022 NOPR, although BHI provided test data for a single unit showing a difference in performance under different conditions, DOE notes that DOE's previous test data, obtained from multiple units, did not indicate conclusively that ambient test conditions within the current bounds cause substantive differences in AFUE. As a result, DOE is not amending the test procedure for consumer boilers to narrow or revise the ambient test conditions at this time due to insufficient conclusive evidence demonstrating the impact on AFUE for various boiler types.

3. Combustion Settings

In the course of the rulemaking for the January 2016 Final Rule, to provide for greater consistency in burner airflow settings during testing, DOE proposed specifying that the excess air ratio, flue oxygen (“O

”) percentage, or flue carbon dioxide (“CO

”) percentage be within the middle 30th percentile of the acceptable range specified in the I&O manual. 80 FR 12876, 12883, 12906 (Mar. 11, 2015). In absence of a specified range in the I&O manual, DOE proposed requiring the combustion airflow to be adjusted to provide between 6.9 percent and 7.1 percent dry flue gas O

, or the lowest dry flue gas O

percentage that produces a stable flame, no carbon deposits, and an air-free flue gas carbon monoxide (“CO”) ratio below 400 parts per million (“ppm”) during the steady-state test described in section 9.1 of ANSI/

ASHRAE 103-2007, whichever is higher. 80 FR 12876, 12906. However, after considering comments regarding the representativeness of the proposal and the potential impact on rated AFUE, DOE determined in the January 2016 Final Rule that further study was needed to determine how such changes would impact AFUE ratings. 81 FR 2628, 2636.

In the May 2020 RFI, DOE requested comment on whether more specific instructions for setting the excess air ratio, flue O

percentage, and/or flue CO

percentage should be provided in the consumer boilers test procedure, and if so, what those instructions should entail. 85 FR 29352, 29356. DOE was particularly interested in understanding whether such a change would improve the representativeness of the test method, and whether it would impact test burden.

In the March 2022 NOPR, after considering comments received in response to the May 2020 RFI, DOE tentatively concluded that it lacked sufficient data and information to indicate that establishing a requirement for setting the excess air ratio, flue O

percentage, and/or flue CO

percentage would provide ratings that are more representative than the ratings provided under the current approach. Therefore, DOE tentatively determined to maintain the current test procedure and did not propose to establish a requirement for setting the excess air ratio, flue O

percentage, and/or flue CO

percentage. 87 FR 14622, 14633.

In response to the March 2022 NOPR, the CA IOUs encouraged DOE to examine the impacts of excess air ratio, flue oxygen percentage, and flue carbon dioxide percentage on AFUE ratings by conducting additional testing. (CA IOUs, No. 20 at p. 2) The Joint Advocates also encouraged DOE to investigate the efficiency impacts of combustion airflow settings and to consider establishing criteria around those settings in the test procedure in order to provide more accurate product rankings. The Joint Advocates asserted that excess air, which can be determined by flue gas O

and CO

concentrations, affects combustion efficiency and, as an example, cited a 2002 fact sheet published by the National Renewable Energy Laboratory that indicated combustion efficiency of commercial boilers can be increased by 1 percent for each 15 percent reduction in excess air ratio.

(Joint Advocates, No. 21 at p. 3-4)

The fact sheet referenced by the Joint Advocates is available at:

https://www.nrel.gov/docs/fy02osti/31496.pdf.

(Last accessed 11/3/2022).

NYSERDA recommended that DOE study how excess oxygen impacts the efficiency of the boiler operation. NYSERDA pointed out that DOE received input from multiple stakeholders regarding changes to excess air ratio, flue O

percentage, and/or flue CO

percentage in the 2016 rulemaking cycle. NYSERDA urged DOE to either revisit this proposal regarding excess oxygen or commit to further study of this topic for a future revision. (NYSERDA, No. 23 at p. 4-5)

Busse suggested updating the test procedure to include two requirements: (1) verify reduced input rate is 98 percent or greater than nameplate minimum input rate and, if less than 98 percent, adjust controls or settings as specified in the I&O manual and restart test at maximum input rate or, if 98 percent or greater, no additional control or setting changes are allowed; and (2) verify combustion products do not exceed 400 parts per million air-free and there are no deposits of carbon on the burner, and correct these conditions, if necessary, as specified in the I&O manual. Busse stated that a reduced input rate below 98 percent of nameplate minimum input rate would likely result in a higher efficiency, and that requiring adjustment and restarting a test when above 102 percent of nameplate minimum input rate could increase test burden. Busse further stated that these provisions would strive towards more accurate AFUE results while not greatly increasing the testing burden. (Busse, No. 22 at p. 10)

In the January 2016 Final Rule, DOE explained that industry stakeholders indicated that the current practice is typically to use the CO

percentage at the “top” of the manufacturer's specified range, and in some cases, even higher than that. Stakeholders provided data suggesting that the impacts on AFUE could be significant but variable,

and there was also concern that some products may not feature any means of providing combustion setting adjustment. Finally, commenters indicated that DOE must evaluate the burden associated with potential re-testing should combustion setting specifications require manufacturers to re-rate their products. As discussed previously, DOE ultimately agreed that further study was needed on the impacts of the CO

percentage on AFUE and, therefore, declined to adopt the proposed amendments. 81 FR 2628, 2635-2636. Thus, there remained a lack of certainty regarding what settings would be most representative of field use.

AHRI stated that the results of the testing of three residential boilers that it conducted at Intertek Testing Laboratories indicate that the proposed revised burner setup requirements change AFUE by 0.3 percent for each 1 percent difference in the CO

values. By contrast, Burnham stated that based on test data that it provided, for an oil-fired hot water boiler with an 11.5 to 12.5 percent CO

adjustment range in the I&O manual, DOE's proposed adjustment would reduce AFUE by as much as 1.0 percent compared to the rating under the existing test procedure. 81 FR 2628, 2636.

DOE did not receive any information in response to the March 2022 NOPR that provided further clarity on this issue. Therefore, DOE has determined that it still lacks sufficient information to indicate that establishing a specification for excess air ratio, flue O

percentage, and/or flue CO

percentage would provide ratings that are more representative than the ratings provided under the current approach, and that doing so would not be unduly burdensome.

Therefore, DOE is maintaining the current instructions and is not establishing additional requirements specifying excess air ratio, flue O

percentage, and/or flue CO

percentage.

4. Supplemental Test Instructions

In the March 2022 NOPR, DOE responded to comments from BHI suggesting that DOE create a repository of supplemental test instructions, similar to that currently in place for commercial boilers,

instead of requiring a waiver to allow for use of specific test instructions not included in the I&O manual or the DOE test procedure. 87 FR 14622, 14635-14636. Specifically, BHI asserted that control systems are increasingly complex, which makes it impractical to run the test without special tools or codes, and that there are safety and reliability concerns with putting testing-specific instructions in the I&O manual. BHI also asserted that the use of the waiver process for these test instruction issues is burdensome, unnecessary, and inconsistent with the test procedure for commercial boilers.

For commercial boilers, DOE provides that a certification report may include supplemental testing instructions, if such information is necessary to run a valid test. Specifically, supplemental information must include any additional testing and testing set-up instructions (

e.g.,

specific operational or control codes or settings) which would be necessary to operate the basic model under the required conditions specified by the relevant test procedure. 10 CFR 429.60(b)(4).

In response, DOE noted that BHI did not provide specific examples of test instructions that would not be able to be included in the I&O manual due to concerns about safety or reliability, and that would thus need to be presented in a waiver. In addition, DOE noted it has not received any petitions for waiver for any basic models of consumer boilers,

indicating there is not a problem with testing absent such additional information. Therefore, DOE did not propose to establish a repository for test instructions for consumer boilers and stated that if testing of a consumer boiler necessitates controls or instructions other than those included in the I&O manual, manufacturers may petition for a waiver under the process established at 10 CFR 430.27. DOE sought further comment on whether supplemental test instructions are necessary for consumer boilers. 87 FR 14622, 14636.

Rheem recommended that DOE use the I&O manual provided with the product as the primary instruction for testing a consumer boiler, and where a manufacturer participates in a third-party certification program (such as AHRI's) and declares supplemental instructions for product testing, the manufacturer should have the option to use such instructions for audit or enforcement testing. (Rheem, No. 18 at p. 5) A.O. Smith recommended that some supplemental instructions from manufacturers could ensure consistency in testing, such as the need to use the recirculation loop to prevent flashing in the heat exchanger or instructions to remove a water temperature sensor and plug the opening. (A.O. Smith, No. 24 at p. 5) Busse suggested that supplemental test instructions are necessary for minimum input rate adjustment (for step-modulating condensing boilers) and for steam boiler low water cutoff (wherein the feature periodically turns off the burner to monitor the settled water level and therefore prevents the boiler from operating continuously during a steady-state test). (Busse, No. 22 at p. 9)

As discussed in the March 2022 NOPR, DOE has not received any petitions for waivers for any basic models of consumer boilers, indicating there is not a problem with testing absent such additional information. Should testing of a consumer boiler necessitate controls or instructions other than those included in the I&O manual, manufacturers may petition for a waiver under the process established at 10 CFR 430.27.

5. Input Rates for Step Modulating Boilers

Appendix N includes a number of specific provisions for consumer boilers with step modulating controls. Boilers with step modulating controls are capable of operating at reduced input rates (

i.e.,

less than that maximum nameplate input rate) and gradually or incrementally increasing or decreasing the input rate as needed to meet the heating load. The test procedure currently requires step modulating boilers to be tested at the maximum rate and the minimum (

i.e.,

reduced) input rate for the steady-state test (referencing section 9.1 of ANSI/ASHRAE 103-1993), the reduced input rate for the cool-down test (referencing section 9.5.2.4 of ANSI/ASHRAE 103-1993), and the reduced input rate for the heat-up test (referencing section 9.6.2.1 of ANSI/ASHRAE 103-1993). In addition, both the optional tracer gas test and the measurement of condensate under cyclic conditions, when conducted, are performed at the reduced input rate (referencing sections 9.7.5 and 9.8 of ANSI/ASHRAE 103-1993, respectively). ANSI/ASHRAE 103-2017 contains the same input rate requirements for modulating boilers as ANSI/ASHRAE 103-1993.

In the May 2020 RFI, DOE requested comment on whether the existing provisions for testing step modulating boilers appropriately reflect the performance of such boilers. If not, DOE sought specific recommendations on the changes that would be necessary to make the test procedure more representative for such products. 85 FR 29352, 29357. Commenters indicated these provisions were adequate, and DOE did not propose any amendments to the provisions for testing step modulating boilers in the March 2022 NOPR. 87 FR 14622, 14633.

In response to the March 2022 NOPR, BWC stated that it appreciated DOE not proposing that step modulating units account for operation at any additional input rates beyond those specified in the current test procedure. BWC stated that the test methods in ANSI/ASHRAE 103-2017 sufficiently measure the performance of these units at different input rates and are representative of a product's average use cycle. (BWC, No. 19, p. 4)

For the reasons discussed in the March 2022 NOPR, and in consideration of the comments received, DOE is not adopting any changes to the provisions for testing step modulating boilers in this final rule.

6. Return Water Temperature

The test procedure at appendix N currently requires a nominal return water temperature (“RWT”) of 120 °F to 124 °F for non-condensing boilers and 120 °F ± 2 °F for condensing boilers (

see

section 7 of appendix N and sections 8.4.2.3 and 8.4.2.3.2 of ANSI/ASHRAE 103-1993, which are incorporated by reference).

In response to the May 2020 RFI, the CA IOUs requested that DOE consider adopting multiple RWTs in the amended test procedure for consumer boilers, consistent with the methodology being developed by the ASHRAE Standard 155P Committee for testing and rating commercial boilers, which requires testing at multiple RWTs depending on the operational characteristics of the boiler. As discussed in the March 2022 NOPR, DOE considers the impact of varying RWTs on field-installed efficiency in its energy conservation standards rulemakings. In the previous energy conservation standards rulemaking for consumer boilers, DOE developed AFUE adjustment factors for low, medium, and high RWT scenarios and estimated that, on average, AFUE would vary from the rated value by 2.66 percent to +3.15 percent depending on the model characteristics and RWT (

see

81 FR 2320, 2354); however, DOE noted there is still a wide range of potential RWTs in the field. Thus, in the March 2022 NOPR, DOE sought additional comment on whether the RWT requirements in the current test method and ANSI/ASHRAE 103-2017 are representative and appropriate, and whether any specific changes to the required conditions could improve representativeness. DOE also sought comment on any associated test burden with changing RWTs. 87 FR 14622, 14633.

In response, the CA IOUs reiterated their request for DOE to review whether the 120 °F RWT requirement is appropriately representative of real-world operating conditions. (CA IOUs, No. 20 at p. 2)

AHRI and AGA & APGA urged DOE to align return water temperatures with those in ANSI/ASHRAE 103-2017. (AHRI, No. 26 at p. 3; AGA & APGA, No. 25 at p. 2)

BWC supported DOE's tentative conclusion of including the single return water temperature specified in ANSI/ASHRAE 103-2017 for ease of comparison between models and manufacturers. (BWC, No. 19 at p. 4) BWC asserted that a single condition would not increase the test burden. (BWC, No. 19 at p. 4)

A.O. Smith commented that the current return water temperature is representative of an average value for the wide range of operating temperatures in the field and indicated that requiring testing to multiple conditions may require adjustment of the standards. A.O. Smith added that non-condensing boilers are more likely to be installed in systems with higher supply and return water temperatures, and condensing boilers are more likely to be installed in systems with lower temperatures. (A.O. Smith, No. 24 at p.

3-4) A.O. Smith stated that testing at multiple water temperatures would add testing burden to a test that could already span two days to complete, and that the burden to retest and rerate products would also include updating heat output ratings and safety certifications. (

Id.

)

Rheem supported maintaining the return water temperature in the current test method, asserting that any change that could make the return water temperature more representative would be outweighed by the testing and certification burden on manufacturers. Specifically, Rheem noted that slight changes to the water temperature would not produce significantly more representative results, and major changes would require retesting of nearly all consumer boilers. (Rheem, No. 18 at p. 4)

Crown and U.S. Boiler supported the use of the water temperatures specified by ANSI/ASHRAE 103-2017 to reduce testing burden and complication. Crown and U.S. Boiler stated that a single set of water temperatures for all types of hot water boilers is appropriate to avoid consumer confusion, increased certification burden, and departure from the industry test method. Crown and U.S. Boiler added that changes to these water temperatures would cause significant changes in AFUE ratings for condensing boilers. (Crown, No. 16 at p. 3-4; U.S. Boiler, No. 17 at p. 3-4)

NYSERDA noted that return water temperature has a significant impact on boiler performance and urged DOE to incorporate return water temperatures that more accurately reflect real-world conditions. NYSERDA stated that the 120 °F return water temperature is too low, does not represent the boiler running conditions according to a research study done by The Electric and Gas Program Administrators of Massachusetts Part of the Residential Evaluation Program Area in 2015,

and should be considered closer to 140 °F. NYSERDA claimed that the rationale for choosing the 120 °F return water temperature from 1978 is outdated and inconsistent with DOE's current test procedure methodologies for commercial HVAC equipment. NYSERDA recommended that DOE test at both 120 °F and 140 °F for return water temperatures but stated that if DOE had to test at only one temperature, it should be 140 °F. (NYSERDA, No. 23 at p. 2-4)

High Efficiency Heating Equipment Impact Evaluation, Prepared for: The Electric and Gas Program Administrators of Massachusetts Part of the Residential Evaluation Program Area, March 2015 at 22, available at

ma-eeac.org/wp-content/uploads/High-Efficiency-Heating-Equipment-Impact-Evaluation-Final-Report.pdf.

The Joint Advocates urged DOE to continue to investigate return water temperatures used in the test procedure to capture more representative performance, directing attention to data presented in appendix 7B to DOE's preliminary analysis technical support document (“TSD”),

which indicated that there was an impact of return water temperature on the thermal efficiency

of a boiler. The Joint Advocates suggested that multiple temperatures (

i.e.,

108 °F and 158 °F) would be more appropriate to be able to differentiate amongst different condensing boiler models, and that non-condensing boilers should be tested at a higher temperature of 158 °F. (Joint Advocates, No. 21 at p. 2-3)

Appendix 7B of the preliminary analysis TSD is available at

www.regulations.gov

at Docket Number EERE-2019-BT-STD-0036. The data can be found in chapter 7B, page 11.

Thermal efficiency for a commercial packaged boiler is determined using test procedures prescribed under 10 CFR 431.86 and is the ratio of the heat absorbed by the water or the water and steam to the higher heating value in the fuel burned. Data presented in the May 2022 Preliminary Analysis TSD reflected the performance of commercial packaged boilers due to the absence of information on consumer boilers.

Busse stated that the current RWT settings were from NBSIR 80-2110 and asserted that the underlying assumptions for the current return water temperature found in NBSIR 80-2110, pages 1-2 are out of date or invalid.

Busse stated that the average distribution system water temperature in the current DOE test procedure should be closer to 133 °F based on heat load calculations to maintain a home at 65 °F. Busse noted that the current test procedure has an average distribution system water temperature of 130 °F (based on a return water temperature of 120 °F and an outlet temperature of 140 °F). However, Busse added that the average distribution system water temperature may be too high based on current or historically available heat distribution products, and that review literature from two cast-iron baseboard manufacturers and two finned-tube copper baseboard manufacturers suggest an average distribution system water temperature of 127 °F would be more representative. Busse stated that current industry practice for step-modulating, condensing boilers may not allow operation at the original 190 °F average boiler water temperature (200 °F supply) or deliver 140 °F supply temperature at the 42 °F average outdoor temperature at the default controller settings. (Busse, No. 22 at p. 2-4) Busse recommended that a separate test should be required for determining heating capacity using a 180 °F return supply water temperature (or the maximum supply temperature allowed by the control system, if less than 200 °F), or, alternatively, the current return water temperature could be used with consideration of sensible heat losses only in order to estimate the steady-state efficiency for a noncondensing operation at high return water temperatures. (Busse, No. 22 at p. 6) Busse also asserted that boilers with reported ratings of 95 percent or 96 percent AFUE have such ratings as a result of a flawed calculation in the current test procedure, which does not account for the portion of the season during which the boiler would operate in a non-condensing mode (due to return water temperatures being higher than 120 °F in certain conditions). (Busse, No. 22 at p. 11-12)

Kelly, George E. and Kuklewicz, Mark E., NBSIR 80-2110: Recommended Testing and Calculation Procedures for Estimating the Seasonal Performance of Residential Condensing Furnaces and Boilers, National Bureau of Standards (Sponsored by U.S. Department of Energy), April 1981.

As acknowledged by commenters, the specification of RWT has a substantive impact on the AFUE of boilers. Condensing boilers in particular achieve higher efficiency levels by extracting latent heat from the flue gases in addition to sensible heat (

i.e.,

the condensation of flue gases releases a substantial amount of energy into the water that is being heated). However, flue gases can condense only if the dew point temperature of the vapor is reached. If the return (inlet) water is hotter than this dew point temperature, then condensation of the flue gases cannot occur in the heat exchanger, and the boiler operates in a non-condensing mode, reducing AFUE.

In addition to the recommendations provided by commenters, DOE research indicates a range of RWTs in consumer applications. DOE is aware that many existing consumer boiler installations require the RWT to be 160 °F and some even as high as 180 °F.

However, as new applications such as radiant floor heating and heat pump boilers become more prevalent in the market, DOE recognizes that some new boilers may be installed in homes that require lower

RWTs. In addition, condensing boilers in new installations would be subject to lower RWTs because radiant floor heating and hydronic air handler applications represent a substantial proportion of new hot water boiler installations.

DOE research indicates some installations have RWT conditions as low as 85 °F in certain cases.

DOE notes that the midpoint of the range of RWTs observed through DOE's research (ranging between 85 °F and 160 °F) is 122 °F, which is reasonably close to the 120 °F condition specified in appendix N and the industry test procedures. Given these considerations, DOE has determined that testing a consumer boiler at a single “high” RWT, as suggested by the Joint Advocates, NYSERDA, and Busse, would be less representative than the conditions specified by the current test procedure.

On May 4, 2022, DOE published in the

Federal Register

a notice of availability of the preliminary analysis for energy conservation standards for consumer boilers (the “May 2022 Preliminary Analysis”). 87 FR 26304. DOE provided a technical support document (“TSD”) for the May 2022 Preliminary Analysis in the rulemaking docket.

Id.

In the energy use analysis of the May 2022 Preliminary Analysis TSD, DOE estimated that 90 percent of condensing boilers installed as replacements to non-condensing boilers would be subject to a higher RWT of 158 °F to 160 °F.

In the May 2022 Preliminary Analysis, DOE estimated that condensing boilers in new installations (new constructions or new owners) would be subject to an average RWT of 108 °F. See Appendix 7B of the preliminary analysis TSD, available at:

www.regulations.gov/document/EERE-2019-BT-STD-0036-0021.

See,

for example:

www.barronheating.com/blog/the-book-on-radiant-heating-when-it-makes-sense-and-when-it-might-not/#:~:text=Radiant%2Dfloor%20heating%20systems%20typically,55%E2%80%9370%C2%B0C).

(Last accessed on October 6, 2022)

DOE also acknowledges the concerns raised by manufacturers regarding the potential need to retest and recertify all consumer boilers if a new test condition were to be required in addition to the currently established 120 °F condition. EPCA requires DOE to establish test procedures that are reasonably designed to produce test results that measure energy efficiency of a consumer boiler during a representative average use cycle or period of use, as determined by the Secretary, and shall not be unduly burdensome to conduct. (42 U.S.C. 6293(b)(3)) Based on the considerations discussed in this section, DOE has determined that it lacks data and information to conclude that a different RWT (or multiple RWTs) would be more representative than the current RWT requirements such that it would justify the potential burden of such a change. Hence, in this final rule, DOE is finalizing its proposal from the March 2022 NOPR to incorporate by reference the test conditions in ANSI/ASHRAE 103-2017. Should additional data or information become available in the future, DOE would consider this topic again in a subsequent test procedure rulemaking.

7. Standby Mode and Off Mode Electrical Energy Consumption

As discussed in section I.A of this final rule, EPCA requires that DOE amend test procedures to include standby mode and off mode energy consumption, “taking into consideration the most current versions of Standards 62301 and 62087 of the International Electrotechnical Commission.” (42 U.S.C. 6295(gg)(2)(A)) The DOE test method currently references IEC 62301 (Edition 2.0 2011-01), which provides instructions for measuring standby mode and off mode energy consumption. IEC 62301 provides several options for measuring the standby mode and off mode power consumption using either the “sampling method,” “average reading method,” or “direct meter reading method.” Although these methods vary, if the standby or off mode consumption is stable, each method can be completed in under 1 hour, and the sampling method can be completed in as little as 15 minutes.

In the March 2022 NOPR, DOE tentatively determined that the provisions in IEC 62301 provide an appropriate representation of standby mode and off mode energy consumption of consumer boilers and are not unduly burdensome; hence DOE did not propose any changes. Because commenters responding to the May 2020 RFI recommended streamlining the procedure for determining standby mode and off mode energy consumption, in the March 2022 NOPR DOE requested further comment on whether a simplified approach for measuring standby mode and off mode electrical energy consumption is appropriate and would provide accurate, representative results that are comparable to those obtained with IEC 62301. 87 FR 14622, 14634.

In response, BWC commented that the standby mode and off mode test methods are appropriate and do not need to be amended at this time. (BWC, No. 19 at p. 4)

Rheem stated that the current approach for measuring standby and off mode electrical energy consumption is not overly burdensome and should be maintained. Rheem also recommended that DOE examine a combined AFUE metric that includes standby and off mode electrical energy use, asserting that an increase in standby and off mode energy use may be needed to accommodate an increase in overall efficiency, and thus a combined AFUE metric would provide for greater design flexibility. (Rheem, No. 18 at p. 4)

DOE considered an integrated AFUE metric (“AFUE

”) in a test procedure final rule published October 20, 2010 (“October 2010 Final Rule”), which established the standby mode and off mode electrical energy use metrics. 75 FR 64621, 64626-64627 (Oct. 20, 2010). In the October 2010 Final Rule, DOE explored the possibility of regulating AFUE

; however, commenters objected that the approach would provide an ineffective basis for regulation, and thus it was not “technically feasible” to integrate AFUE with standby mode and off mode energy consumption.

Id.

Separate metrics were established because the magnitude of the standby mode and off mode energy consumption was very small compared to the active mode fuel consumption, and, as a result, it was not possible to discern different levels of standby and off mode power consumption (

i.e.,

AFUE

values were essentially identical to AFUE values).

Id.

Neither Rheem nor other commenters have presented DOE with any information to suggest that the conclusions from the October 2010 Final Rule—specifically, that an integrated metric would not be technically feasible—are no longer applicable. Furthermore, DOE is not aware of any current industry-accepted test procedure that combines the current AFUE metric with the standby mode and off mode power consumption metrics. For these reasons, DOE is not adopting any new provisions for a combined metric in this final rule.

A.O. Smith recommended eliminating the standby mode and off mode power consumption testing due to the little impact the associated power consumption has on the total efficiency of a consumer boiler (less than a fraction of one percent). A.O. Smith indicated that procuring the adequate equipment and instrumentation required for this testing is burdensome. A.O. Smith also commented that removing these requirements would afford manufacturers the opportunity to potentially add safety enhancements such as carbon monoxide sensors, which require a small heating element to prevent premature failure, as well as options for control displays and ways to reduce cycling losses. (A.O. Smith, No. 24 at p. 4) A.O. Smith recommended that if DOE were to keep the standby mode and off mode tests as part of the test procedure, the standby mode and off mode power consumption should be measured with a simple current measurement with a calibrated watt meter. (A.O. Smith, No. 24 at p. 6)

As discussed, EPCA requires that DOE include in its test procedures a method

for measuring standby mode and off mode power consumption, unless technically infeasible. (42 U.S.C. 6295(gg)(2)(A)) Further, in doing so, EPCA requires that DOE must consider IEC Standard 62301 and IEC Standard 62087. (42 U.S.C. 6295(gg)(2)(A)) Section 4.4 of IEC 62301 provides instruction on selecting acceptable power measuring instrumentation by specifying power measurement uncertainty bounds, frequency response, and long-term averaging (integrating) requirements. DOE notes that if a calibrated watt meter is capable of meeting these requirements, then it may be used in accordance with section 4.4 of IEC 62301.

AHRI noted that standby mode and off mode power consumption should not count as a loss because all energy brought into the system provides useful resistive heat to the building. AHRI stated that similar logic is used to give electric boilers a rating of 100 percent efficiency. (AHRI, No. 26 at p. 3)

While electrical component power draws that dissipate small amounts of heat to the surroundings may contribute to useful heating to the building, the building does not always demand heating. During the cooling season, any heat dissipated would be counterproductive. Furthermore, not all boilers are located in conditioned spaces. In addition, as discussed previously, EPCA requires DOE to include in its test procedures a method for measuring standby mode and off mode power consumption. (42 U.S.C. 6295(gg)(2)(A)) For these reasons, DOE makes no change to its inclusion of standby mode and off mode power in this final rule.

In conclusion, DOE has determined that no changes to the standby mode and off mode test provisions are warranted. As such, the new appendix EE test procedure maintains the same test methods for measuring these metrics as specified in the current appendix N test procedure.

8. Full Fuel Cycle Efficiency

The full fuel cycle (“FFC”) accounts for the energy consumed in extracting, processing, and transporting fuels. In the March 2022 NOPR, DOE responded to comments received in response to the May 2020 RFI requesting that DOE consider incorporating an FFC analysis into the test procedure in order to allow for direct comparisons between fossil fuel-fired systems and electric systems. 87 FR 14622, 14634. DOE responded that FFC is typically considered in energy conservation standards rulemakings—not as a metric for representing product efficiency.

Id.

In the March 2022 NOPR, DOE maintained its previous conclusion from the January 2016 Final Rule that a mathematical adjustment to the test procedure to account for FFC is not appropriate because the mathematical adjustment to the site-based energy descriptor relies on information that is updated annually, which would require annual updating of the test method.

Id.

In response to the March 2022 NOPR, BWC stated that the FFC efficiency and source efficiency analysis are not appropriate to include in the Federal test procedure. (BWC, No. 19, p. 4)

For the reasons discussed in the March 2022 NOPR, DOE maintains in this final rule its previous determination not to account for FFC in the consumer boiler test procedure.

9. Idle Losses

In the March 2022 NOPR, DOE responded to comments received in response to the May 2020 RFI requesting that DOE consider “idle losses” that are not captured in the AFUE metric. 87 FR 14622, 14628. Specifically, Energy Kinetics asserted that oversizing of boilers can lead to wasted energy to heat up the boiler but not contribute to the heating of the hydronic loop. In the March 2022 NOPR, DOE stated that EPCA (42 U.S.C. 6295(f)(3)(A)-(B)) requires hot water boilers to have an automatic means for adjusting water temperature, which limits idle losses. DOE indicated that idle losses could be further addressed in the determination of AFUE; however, there was insufficient data to propose amendments to the test procedure to do so. DOE sought further comment from interested parties on the topic. 87 FR 14622, 14628.

In response to the March 2022 NOPR, Rheem agreed with DOE's statement that the prescriptive design requirements in EPCA at 42 U.S.C. 6295(f)(3) effectively reduce idle losses in the field. Rheem noted that if idle losses, both electrical and fossil fuel, were fully accounted for in the AFUE metric, then a standard could be proposed that would not require separate design requirements. (Rheem, No. 18 at p. 5)

DOE has determined that there remains insufficient information to further address idle losses in this rulemaking as it pertains to the determination of AFUE in the new appendix EE test procedure for consumer boilers.

H. Alternative Efficiency Determination Methods

At 10 CFR 429.70, DOE includes provisions for alternative efficiency determination methods (“AEDMs”), which are computer modeling or mathematical tools that predict the performance of non-tested basic models. They are derived from mathematical models and engineering principles that govern the energy efficiency and energy consumption characteristics of a type of covered equipment. These computer modeling and mathematical tools, when properly developed, can provide a relatively straight-forward and reasonably accurate means to predict the energy usage or efficiency characteristics of a basic model of a given covered product or equipment and reduce the burden and cost associated with testing. 78 FR 79579, 79580 (Dec. 31, 2013; the “December 2013 AEDM Final Rule”). Where authorized by regulation, AEDMs enable manufacturers to rate and certify their basic models by using the projected energy use or energy efficiency results derived from these simulation models in lieu of testing.

Id.

at 78 FR 79580.

DOE does not currently authorize the use of AEDMs for consumer boilers, whereas DOE does authorize the use of AEDMs for commercial packaged boilers.

Manufacturers of consumer boilers (or furnaces more generally) are not authorized to use an AEDM to determine ratings for these products. However, manufacturers of cast-iron boilers may determine AFUE for models at a capacity other than the highest or lowest of the group of basic models having identical intermediate sections and combustion chambers through linear interpolation of data obtained for the smallest and largest capacity units of the family.

See

10 CFR 429.18(a)(2)(iv)(A). These provisions already provide manufacturers with an alternative method of rating consumer boilers without testing every model, and this alternative method reduces manufacturer test burden.

In the December 2013 AEDM Final Rule, DOE explained that the AEDM provisions extend to those products or equipment which “have expensive or highly-customized basic models.” 78 FR 79579, 79580. The current AEDM provisions for commercial HVAC equipment (including commercial package boilers, for example) were in part the result of a negotiated rulemaking effort by the Appliance Standards and Rulemaking Federal Advisory Committee (ASRAC) in 2013.

Id.

Boilers designed for residential applications were not considered at the time. 78 FR 79579.

In the March 2022 NOPR, DOE requested comment on whether AEDM provisions similar to those in place for commercial equipment would be necessary and appropriate for consumer boilers. 87 FR 14622, 14635.

A.O. Smith stated that adding an AEDM option for consumer boilers would be reasonable; however, there is

greater value to have an AEDM for commercial products given that those models can be engineered to order. (A.O. Smith, No. 24 at p. 4) Busse indicated that the breadth of a product line with similar geometries and performance would not seem to justify an AEDM; however, an AEDM may be the only method to avoid testing each model. (Busse, No. 22 at p. 8)

In consideration of these comments, as well as considerations discussed in the March 2022 NOPR (

see

87 FR 14622, 14635), in this final rule, DOE concludes that manufacturer testing burden is alleviated by the linear interpolation provisions for cast-iron boilers, such that an AEDM for consumer boilers more broadly is not warranted at this time.

I. Certification Provisions for Cast-Iron Boilers

As discussed in the March 2022 NOPR, the certification provisions at 10 CFR 429.18(a)(2)(iv)(A) alleviate testing burden for cast-iron boilers, which are commonly constructed of identical cast-iron heat exchanger sections. Boilers of the same cast-iron product family are often constructed so that the heating capacity can be increased by adding more sections to the heat exchanger. When a product family is designed in this way, linear interpolation is accurate

to predict the performance of intermediately-sized boilers. The March 2022 NOPR sought data and other information that would demonstrate that using a linear interpolation method for heat exchanger materials other than cast-iron would produce representative test results. 87 FR 14622, 14635.

Test data analyzed as part of the 1979 rulemaking which established these provisions showed that the annual fuel utilization efficiency, energy consumption, and estimated annual operating cost of sectional cast-iron boilers can be accurately predicted by a linear interpolation based on data obtained from units having the smallest and largest number of intermediate sections. 44 FR 22410, 22415 (April 13, 1979).

AHRI and AGA and APGA supported extendin

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