Energy Conservation Program for Certain Commercial and Industrial Equipment: Test Procedure for Commercial Water Heating Equipment

Federal RegisterMay 9, 2016

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DEPARTMENT OF ENERGY

10 CFR Parts 429, 430, and 431

[Docket No. EERE-2014-BT-TP-0008]

RIN 1904-AD18

Energy Conservation Program for Certain Commercial and Industrial Equipment: Test Procedure for Commercial Water Heating Equipment

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NOPR) and announcement of public meeting.

SUMMARY:

The U.S. Department of Energy (DOE) proposes to revise its test procedures for commercial water heaters, unfired hot water storage tanks, and hot water supply boilers (henceforth, “commercial water heating (CWH) equipment”) established under the Energy Policy and Conservation Act of 1975 (EPCA), as amended. In this NOPR, DOE proposes several changes, including: Updating references of industry test standards to incorporate by reference the most recent versions of the industry standards; proposing modifications to the existing test methods for certain classes of CWH equipment; developing new test procedures for determining the efficiency of unfired hot water storage tanks, commercial heat pump water heaters, and flow-activated instantaneous water heaters; proposing clarifications on test set-up and settings for various classes of CWH equipment; revising the certification requirements for CWH equipment; and proposing associated implementing regulations including definitions. DOE announces a public meeting to receive comment on these proposed test procedure amendments, and it also welcomes written comments and data from the public on all aspects of this proposal.

DATES:

Meeting:

DOE will hold a public meeting on June 6, 2016, from 9:30 a.m. to 12:00 p.m., in Washington, DC. The meeting will also be broadcast as a webinar. See section V, “Public Participation,” for webinar registration information, participant instructions, and information about the capabilities available to webinar participants.

Comments:

DOE will accept comments, data, and information regarding this NOPR before and after the public meeting, but no later than July 8, 2016. See section V, “Public Participation,” for details.

ADDRESSES:

The public meeting will be held at the U.S. Department of Energy, Forrestal Building, Room 8E-089, 1000 Independence Avenue SW., Washington, DC 20585. To attend, please notify Ms. Brenda Edwards at (202) 586-2945. Further attendance instructions can be found in section V, “Public Participation.”

Instructions:

All comments submitted must identify the NOPR for Test Procedures for Commercial Water Heating Equipment, and provide docket number EERE-2014-BT-TP-0008 and/or regulatory identification number (RIN) 1904-AD18. Interested persons are encouraged to submit comments using the Federal eRulemaking Portal at

www.regulations.gov

. Follow the instructions for submitting comments. Alternatively, interested persons may submit comments by any of the following methods:

•

Email:

CommWaterHeatingEquip 2014TP0008@ee.doe.gov

. Include the docket number and/or RIN in the subject line of the message. Submit electronic comments in WordPerfect, Microsoft Word, PDF, or ASCII file format, and avoid the use of special characters or any form of encryption.

•

Postal Mail:

Ms. Brenda Edwards, U.S. Department of Energy, Building Technologies Office, Mailstop EE-5B, 1000 Independence Avenue SW., Washington, DC 20585-0121. If possible, please submit all items on a compact disc (CD), in which case it is not necessary to include printed copies.

•

Hand Delivery/Courier:

Ms. Brenda Edwards, U.S. Department of Energy, Building Technologies Office, 950 L'Enfant Plaza SW., Suite 600, Washington, DC 20024. Telephone: (202) 586-2945. If possible, please submit all items on a CD, in which case it is not necessary to include printed copies.

DOE will not accept telefacsimilies (faxes). For detailed instructions on submitting comments and additional information on the rulemaking process, see section V of this document (Public Participation).

Docket:

The docket is available for review at

www.regulations.gov

, including

Federal Register

notices, public meeting attendee lists and transcripts, comments, and other supporting documents/materials. 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 information that is exempt from public disclosure.

A link to the docket Web page can be found at:

http://www.regulations.gov/#!docketDetail;D=EERE-2014-BT-TP-0008

. This Web page contains a link to the docket for this rulemaking on the

www.regulations.gov

site. The

www.regulations.gov

Web page contains simple instructions on how to access all documents, including public comments, in the docket. See section V, “Public Participation,” for further information on how to submit comments through

www.regulations.gov.

For further information on how to submit a comment, review other public comments and the docket, or participate in the public meeting, contact Ms. Brenda Edwards at (202) 586-2945 or by email:

Brenda.Edwards@ee.doe.gov.

FOR FURTHER INFORMATION CONTACT:

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

Ashley.Armstrong@ee.doe.gov.

Mr. Eric Stas, U.S. Department of Energy, Office of the General Counsel, GC-33, 1000 Independence Avenue SW., Washington, DC 20585-0121. Telephone: (202) 586-9507. Email:

Eric.Stas@hq.doe.gov.

For more information on how to submit a comment, or review other public comments and the docket, contact Ms. Brenda Edwards, U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Office, Mailstop EE-5B, 1000 Independence Avenue SW., Washington, DC 20585-0121. Telephone: (202) 586-2945. Email:

Brenda.Edwards@ee.doe.gov.

SUPPLEMENTARY INFORMATION:

DOE intends to incorporate by reference the following industry standards into part 431:

(1) Gas Appliance Manufacturers Association (GAMA) Standard IWH-TS-1, March 2003 edition, “Method to Determine Performance of Indirect-Fired Water Heaters,” sections 4, 5, 6.0, and 6.1;

(2) American National Standards Institute (ANSI) Standard Z21.10.3-2015/Canadian Standards Association (CSA) Standard 4.3-2015, “Gas-fired Water Heaters, Volume III, Storage Water Heaters with Input Ratings Above 75,000 Btu Per Hour, Circulating and Instantaneous,” annex E.1;

(3) ANSI/American Society of Heating Refrigeration and Air-Conditioning Engineers (ASHRAE) Standard 118.1-2012, “Method of Testing for Rating Commercial Gas, Electric, and Oil Service Water-Heating Equipment”;

(4) ASTM International (ASTM) C177-13, “Standard Test Method for

Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus”;

(5) ASTM C518-10, “Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus;” and

(6) ASTM D2156-09, “Standard Test Method for Smoke Density in Flue Gases from Burning Distillate Fuels.”

Copies of GAMA IWH-TS-1, March 2003 edition, can be obtained from the Air-conditioning, Heating, and Refrigeration Institute (AHRI), 2111 Wilson Blvd., Suite 500, Arlington, VA 22201, (703) 524-8800, or by going to

http://www.ahrinet.org/App_Content/ahri/files/standards%20pdfs/Indirect-Fired%20Water%20Heater%20Testing%20Standard03.pdf.

Copies of ANSI Z21.10.3-2015/CSA 4.3-2015 and ANSI/ASHRAE 118.1-2012 can be obtained from the American National Standards Institute, 25 W. 43rd Street, 4th Floor, New York, NY 10036, (212) 642-4800, or by going to

http://webstore.ansi.org/.

Copies of ASTM C177-13, ASTM C518-10, and ASTM D2156-09 can be obtained from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, (610) 832-9585, or by going to

http://www.astm.org/Standard/index.html

See IV.M. for a further discussion of these standards.

Table of Contents

I. Authority and Background

II. Synopsis of the Notice of Proposed Rulemaking

III. Discussion

A. Updated Industry Test Methods

1. ANSI Z21.10.3 Testing Standard

2. ASTM Standard Test Method D2156

3. ASTM Test Standards C177-13 and C518-10

B. Test Method Repeatability and Ambient Test Conditions

C. Test Method for Unfired Hot Water Storage Tanks

D. Procedure for Setting the Tank Thermostat for Storage and Storage-Type Instantaneous Water Heaters

E. Clarifications to the Thermal Efficiency and Standby Loss Test Procedures

F. Definitions for Certain Consumer Water Heaters and Commercial Water Heating Equipment

1. Consumer Water Heaters

2. Commercial Water Heating Equipment

3. Residential-Duty Commercial Water Heaters

4. Storage-Type Instantaneous Water Heaters

G. Standby Loss Test for Flow-Activated Instantaneous Water Heaters

H. Test Set Up for Commercial Instantaneous Water Heaters and Hot Water Supply Boilers

I. Changes to the Standby Loss Test for Instantaneous Water Heaters and Hot Water Supply Boilers Other Than Flow-Activated Instantaneous Water Heaters

J. Test Procedure for Rating Commercial Heat Pump Water Heaters

K. Fuel Input Rate

L. Default Values for Certain Test Parameters for Commercial Water Heating Equipment

M. Certification Requirements

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Orders 12866

B. Review Under the Regulatory Flexibility Act

C. Review Under the Paperwork Reduction Act of 1995

D. Review Under the National Environmental Policy Act of 1969

E. Review Under Executive Order 13132

F. Review Under Executive Order 12988

G. Review Under the Unfunded Mandates Reform Act of 1995

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

I. Review Under Executive Order 12630

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

K. Review Under Executive Order 13211

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

M. Description of Materials Incorporated by Reference

V. Public Participation

A. Attendance at the Public Meeting

B. Procedure for Submitting Requests To Speak and Prepared General Statements for Distribution

C. Conduct of the Public Meeting

D. Submission of Comments

E. Issues on Which DOE Seeks Comment

VI. Approval of the Office of the Secretary

I. Authority and Background

Title III, Part C

of the Energy Policy and Conservation Act of 1975 (EPCA or the Act), Public Law 94-163 (42 U.S.C. 6311-6317, as codified), added by Public Law 95-619, Title IV, section 441(a), sets forth a variety of provisions designed to improve energy efficiency.

It established the “Energy Conservation Program for Certain Industrial Equipment,” a program covering certain commercial and industrial equipment (hereafter referred to as “covered equipment”), which includes the commercial water heating (CWH) equipment that is the subject of this rulemaking. (42 U.S.C. 6311(1)(K)) Title III, Part B

of EPCA (42 U.S.C. 6291-6309, as codified) sets forth a variety of provisions designed to improve energy efficiency and established the Energy Conservation Program for Consumer Products Other Than Automobiles. This includes consumer water heaters, which are also addressed in this rulemaking. (42 U.S.C. 6292(a)(4))

For editorial reasons, Part C was codified as Part A-1 in the U.S. Code.

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

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

Under EPCA, energy conservation programs generally consist of four parts: (1) Testing; (2) labeling; (3) establishing Federal energy conservation standards; and (4) certification and enforcement procedures. The testing requirements consist of test procedures that manufacturers of covered products and equipment must use as both the basis for certifying to DOE that their products and equipment comply with the applicable energy conservation standards adopted pursuant to EPCA, and for making representations about the efficiency of that equipment. (42 U.S.C. 6293(c); 42 U.S.C. 6295(s); 42 U.S.C. 6314; 42 U.S.C. 6316)

The initial test procedures for CWH equipment were added to EPCA by the Energy Policy Act of 1992 (EPACT 1992), Public Law 102-486, and correspond to those referenced in ASHRAE and Illuminating Engineering Society of North America (IESNA) Standard 90.1-1989 (

i.e.,

ASHRAE Standard 90.1-1989) which went into effect on October 24, 1992. (42 U.S.C. 6314(a)(4)(A)) EPCA requires that if an industry test procedure that is referenced in ASHRAE Standard 90.1 is amended, DOE must amend its test procedure to be consistent with the amended industry test procedure, unless DOE determines that the amended test procedure is not reasonably designed to produce test results that reflect the energy efficiency, energy use, or estimated operating costs of the equipment during a representative average use cycle. In addition, DOE must determine that the amended test procedure is not unduly burdensome to conduct. (42 U.S.C. 6314(a)(2), (3) and (4)(B))

If DOE determines that a test procedure amendment is warranted, it must publish a proposed test procedure in the

Federal Register

and offer the public an opportunity to present oral and written comments. (42 U.S.C. 6314(b)(1)-(2)) When amending a test procedure, DOE must determine to what extent, if any, the proposed test procedure would alter the equipment's energy efficiency as determined under the existing test procedure. (42 U.S.C. 6293(e); 42 U.S.C. 6314(a)(4)(C))

The Energy Independence and Security Act of 2007 (EISA 2007), Public Law 110-140, amended EPCA to require that at least once every 7 years, DOE must review test procedures for each type of covered equipment, including CWH equipment, and either: (1) Amend the test procedures if the Secretary determines that the amended test procedures would more accurately or

fully comply with the requirements of 42 U.S.C. 6314(a)(2)-(3),

or (2) publish a notice of determination not to amend a test procedure. (42 U.S.C. 6314(a)(1)(A)) Under this requirement, DOE must review the test procedures for CWH equipment no later than May 16, 2019, which is 7 years after the most recent final rule amending the Federal test method for CWH equipment.

The final rule resulting from this rulemaking will satisfy the requirement to review the test procedure for CWH equipment within 7 years.

42 U.S.C. 6314(a)(2) requires that test procedures be reasonably designed to produce test results which reflect energy efficiency, energy use, and estimated operating costs of a type of industrial equipment (or class thereof) during a representative average use cycle (as determined by the Secretary), and not be unduly burdensome to conduct.

42 U.S.C. 6314(a)(3) requires that if the test procedure is a procedure for determining estimated annual operating costs, such procedure must provide that such costs are calculated from measurements of energy use in a representative average-use cycle (as determined by the Secretary), and from representative average unit costs of the energy needed to operate such equipment during such cycle. The Secretary must provide information to manufacturers of covered equipment regarding representative average unit costs of energy.

DOE published a final rule in the

Federal Register

on May 16, 2012, that, in relevant part, amended its test procedure for commercial water-heating equipment. 77 FR 28928.

DOE's test procedure for CWH equipment is found at 10 CFR 431.106,

Uniform test method for the measurement of energy efficiency of commercial water heaters and hot water supply boilers (other than commercial heat pump water heaters).

DOE's test procedure for CWH equipment provides a method for determining the thermal efficiency and standby loss of CWH equipment. In a direct final rule for test procedures for CWH equipment, DOE incorporated by reference certain sections of the ANSI Standard Z21.10.3-1998 (ANSI Z21.10.3-1998),

Gas Water Heaters, Volume III, Storage Water Heaters With Input Ratings Above 75,000 Btu Per Hour, Circulating and Instantaneous.

69 FR 61974, 61983 (Oct. 21, 2004). On May 16, 2012, DOE published a final rule for certain commercial heating, air-conditioning, and water-heating equipment in the

Federal Register

that, among other things, updated the test procedures for certain CWH equipment by incorporating by reference ANSI Z21.10.3-2011. 77 FR 28928, 28996. These updates did not materially alter DOE's test procedure for CWH equipment.

DOE has reserved a place in its regulations for a test procedure for commercial heat pump water heaters at 10 CFR 431.107,

Uniform test method for the measurement of energy efficiency for commercial heat pump water heaters.

The American Energy Manufacturing Technical Corrections Act (AEMTCA), Public Law 112-210, was signed into law on December 18, 2012, and amended EPCA to require that DOE publish a final rule establishing a uniform efficiency descriptor and accompanying test methods for consumer water heaters and certain CWH equipment. (42 U.S.C. 6295(e)(5)) AEMTCA required DOE to replace the current efficiency metric for consumer water heaters (energy factor) and the current efficiency metrics for commercial water heaters (thermal efficiency and standby loss) with a uniform efficiency descriptor. (42 U.S.C. 6295(e)(5)(C)) Further, AEMTCA required that the uniform efficiency descriptor and accompanying test method apply, to the maximum extent possible, to all water heating technologies currently in use and to future water heating technologies. (42 U.S.C. 6295(e)(5)(H)) However, AEMTCA allowed DOE to exclude from the uniform efficiency descriptor, specific categories of covered water heaters that do not have residential uses, that can be clearly described, and that are effectively rated using the current thermal efficiency and standby loss descriptors. (42 U.S.C. 6295(e)(5)(F))

DOE published a final rule for test procedures for certain CWH equipment on July 11, 2014 (“July 2014 final rule”). 79 FR 40542. The final rule modified the current consumer water heater metric (energy factor) to create uniform energy factor (UEF), the descriptor to be used as the uniform efficiency descriptor for all consumer water heaters and certain CWH equipment that have residential uses.

Id.

at 40544. The final rule excluded certain CWH equipment from the uniform descriptor equipment that has no residential use, that can be clearly identified and described, and that are effectively rated using the current thermal efficiency and standby loss efficiency descriptors. In the July 2014 final rule, DOE defined and adopted a new test method for “residential-duty commercial water heaters,” which are commercial water heaters that have residential uses.

Id.

In this rulemaking for CWH equipment test procedures, DOE only considers amended test procedures for the CWH equipment classes that do not have residential applications and that are not “residential-duty commercial water heaters” as adopted in the July 2014 final rule.

On February 27, 2014, DOE published in the

Federal Register

a request for information (February 2014 RFI) to seek public comments on several issues associated with the current test procedure for CWH equipment. 79 FR 10999. DOE accepted comments and information on the February 2014 RFI until March 31, 2014, and considered all feedback received when developing the proposals contained in this rulemaking. Each of the issues raised in the February 2014 RFI is discussed in detail in section III, along with comments received on the issues and DOE's responses. In addition, several topics not addressed in the February 2014 RFI but brought up by interested parties in their comments are discussed in section III of this NOPR.

Although DOE did not consider amended test procedures for residential-duty commercial water heaters, DOE proposes to amend the definitions pertaining to these equipment, as discussed in section III.F.3.

In support of its rulemaking effort, DOE typically seeks comments from the public and uses them to conduct in-depth technical analyses of publicly-available test standards and other relevant information. As noted above, this NOPR discusses the comments received by DOE in response to the February 2014 RFI and summarizes all proposed updates and amendments to the current test procedure. In its efforts to continually engage the public and interested parties in the rulemaking process, DOE seeks data and public input on all aspects of this rulemaking, in order to improve the testing methodologies, to accurately reflect commercial use, and to produce repeatable results. DOE also requests feedback from interested parties and stakeholders on the proposed amendments to the current test procedures for CWH equipment.

II. Synopsis of the Notice of Proposed Rulemaking

The February 2014 RFI raised several issues regarding the thermal efficiency and standby loss test methods for CWH equipment. Several other issues which were not part of the RFI were brought up through stakeholder feedback and comments on the RFI. In this NOPR, DOE discusses all issues identified by DOE and interested parties, and proposes to modify the current test procedures based on these issues, as necessary, in order to improve the consistency and accuracy of test results generated using the DOE test procedure while minimizing test burden.

As provided in 10 CFR 431.105, the current DOE test procedure incorporates by reference the ANSI Z21.10.3-2011 test method for use in 10 CFR 431.106, and that latter provision specifically directs one to follow Exhibits G.1 and

G.2 of the industry test procedure. In 2013, ANSI updated its test method and released a more recent version,

i.e.,

ANSI Z21.10.3-2013/Canadian Standards Association (CSA) 4.3-2013,

Gas-fired Water Heaters, Volume III, Storage Water Heaters with Input Ratings Above 75,000 Btu Per Hour, Circulating and Instantaneous

(hereinafter referred to as “ANSI Z21.10.3-2013”). In the February 2014 RFI, DOE stated its plan to amend its test procedure to reference ANSI Z21.10.3-2013, the updated industry test method for measuring thermal efficiency and standby loss. 79 FR 10999, 11001-11002 (Feb. 27, 2014). However, since publication of the February 2014 RFI, ANSI updated its test method twice. First, an updated version was approved on July 2, 2014, and released in August 2014, specifically, ANSI Z21.10.3-2014/CSA 4.3-2014,

Gas-fired Water Heaters, Volume III, Storage Water Heaters with Input Ratings Above 75,000 Btu Per Hour, Circulating and Instantaneous

(hereinafter referred to as “ANSI Z21.10.3-2014”). Another updated version was then approved on October 5, 2015, and released in November 2015, specifically, ANSI Z21.10.3-2015/CSA 4.3-2015,

Gas-fired Water Heaters, Volume III, Storage Water Heaters with Input Ratings Above 75,000 Btu Per Hour, Circulating and Instantaneous

(hereinafter referred to as “ANSI Z21.10.3-2015”). DOE is proposing to incorporate by reference annexes E.1 of this latest industry test procedure (ANSI Z21.10.3-2015) for measuring thermal efficiency and standby loss.

After a careful review of ANSI Z21.10.3-2015, DOE found one significant difference between the sections of the test standard that are currently referenced by DOE (

i.e.,

Exhibits G.1 and G.2 of ANSI Z21.10.3-2011) and those contained in ANSI Z21.10.3-2015 (

i.e.,

Annexes E.1 and E.2). This difference is in the temperature differential terms used in the equations to calculate standby loss in Annex E.2 of ANSI Z21.10.3-2015 and Exhibit G.2 of ANSI Z21.10.3-2011. The equations in Annex E.2 of ANSI Z21.10.3-2015 and Exhibit G.2 of ANSI Z21.10.3-2011 are meant to calculate standby loss, which is defined as the average hourly energy required to maintain the stored water temperature expressed as a percentage of the total heat content of the stored water above room temperature. However, the temperature differential term used in the denominator of the standby loss equation in Annex E.2 of ANSI Z21.10.3-2015 does not represent the total heat content of the water heater. Therefore, DOE has tentatively concluded that it is appropriate to use the standby loss equation in Exhibit G.2 of ANSI Z21.10.3-2011, which is both accurate and best represents the standby loss expressed as a percentage per hour of the total heat content of the stored water above room temperature. Therefore, DOE proposes to include the equation for standby loss `S' presented in Exhibit G.2 of ANSI Z21.10.3-2011 in the DOE test procedure for all covered commercial storage water heaters and storage-type instantaneous water heaters (see section III.F for discussion on DOE's proposed definition for “storage-type instantaneous water heater”). However, for instantaneous water heaters and hot water supply boilers other than storage-type instantaneous water heaters, DOE proposes separate standby loss test procedures and equations, as discussed in sections III.G and III.I. DOE did not find any other significant differences between Annexes E.1 and E.2 of ANSI Z21.10.3-2015 and Exhibits G.1 and G.2 of ANSI Z21.10.3-2011. Therefore, other than the reference for the standby loss equation, DOE proposes to update the reference in its test procedures for CWH equipment (as applicable) to the most recent version of the industry test standard. Specifically, DOE proposes to incorporate by reference Annex E.1 of ANSI Z21.10.3-2015. This issue is further discussed in section III.A of this rulemaking.

DOE's current test procedure for oil-fired CWH equipment at 10 CFR 431.106 also refers to ASTM Standard D2156-80 (“ASTM D2156-80”), “Standard Test Method for Smoke Density in Flue Gases from Burning Distillate Fuels.” Specifically, this industry method is cited to determine that smoke in the flue does not exceed a No. 1 smoke spot number. A more recent version of this standard, ASTM Standard D2156-09 (“ASTM D2156-09”), “Standard Test Method for Smoke Density in Flue Gases from Burning Distillate Fuels,” was approved in 2009 and reapproved in 2013. DOE carefully reviewed the two versions of this industry method and identified no significant differences that would affect the determination of smoke spot number as referred to in DOE's test procedure. Therefore, DOE proposes to incorporate by reference ASTM D1256-09 for the purpose of determining the smoke spot number.

However, DOE also proposes clarifications to the procedure for determining the smoke spot number. First, DOE proposes to clarify that the smoke spot number must be determined prior to taking measurements for the efficiency tests (

i.e.,

the thermal efficiency test or standby loss test). Specifically, for the thermal efficiency test, DOE proposes to require that the smoke spot number be determined after a steady-state condition has been reached but before beginning measurements for the thermal efficiency test. For the standby loss test, DOE proposes to require that the smoke spot number be determined after the first cut-out before beginning measurements for the standby loss test. However, DOE proposes not to require that the smoke spot test be conducted prior to beginning an efficiency test (

i.e.,

thermal efficiency or standby loss) if no settings on the water heater have been changed and the water heater has not been turned off since the end of a previously run efficiency test. DOE also proposes that the requirements for when to conduct the smoke spot test also apply to measurement of the CO

reading, which is required by DOE's current test procedures for oil-fired CWH equipment at 10 CFR 431.106. Second, DOE proposes to require that the smoke measuring device be connected to an open-ended tube that projects into the flue

1/4

1/2

of the pipe diameter. This proposed clarification regarding the smoke measuring device is based on the requirements for commercial space-heating boilers in the ANSI/AHRI Standard 1500 (“AHRI 1500-2015”), “2015 Standard for Performance Rating of Commercial Space Heating Boilers.” Because this requirement comes from an industry-accepted test method, DOE expects this requirement to lead to minimal test burden for manufacturers and would simply serve to clarify the test set-up.

DOE's current definition for “R-value” at 10 CFR 431.102 references two industry test methods: (1) ASTM Standard Test Method C177-97 (“ASTM C177-97”), “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus”; and (2) ASTM Test Standard C518-91 (“ASTM C518-91”), “Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus.” More recent versions of ASTM C177 and ASTM C518 were published in October 2013 and June 2010, respectively: (1) ASTM Standard Test Method C177-13 (“ASTM C177-13”), “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus”; and (2) ASTM Test

Standard C518-10 (“ASTM C518-10”), “Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus.” After careful review, DOE has tentatively concluded that there are no substantive differences in the procedures for measuring R-value between the two versions of ASTM C177 or between the two versions of ASTM C518. Based upon its analysis, DOE proposes to incorporate by reference ASTM Standard Test Methods C177-13 and C518-10 and update its references to these versions in the definition for “R-value” at 10 CFR 431.102, in order to maintain up-to-date references to industry test methods.

Among the comments received by DOE on the published RFI, several commenters raised concerns with regards to the repeatability of the standby loss test method as set forth in the current DOE test method (which references Exhibit G.2 of ANSI Z21.10.3-2011). To address these concerns of test repeatability, DOE proposes several improvements to both the thermal efficiency and standby loss test methods, which are discussed in detail in section III.B of this rulemaking.

Unfired hot water storage tanks are covered equipment included in the scope of this rulemaking. These tanks store hot water and do not consume fuel or electricity for the purpose of heating water, so any energy efficiency improvements would target standby loss associated with heat loss from the stored water. Currently, unfired hot water storage tanks are required to have thermal insulation with a minimum thermal resistance (R-value) of 12.5 °F·ft

·hr/Btu.

See

10 CFR 431.110. In the February 2014 RFI, DOE requested comment on whether the R-value requirement was an appropriate energy efficiency descriptor and whether it should adopt a standby loss test and metric to replace the current R-value requirement. DOE also noted that determining the R-value of a single sample does not assess whether this value is applicable to the entire tank surface area, including bottom, top, and fitting areas. 79 FR 10999, 11002 (Feb. 27, 2014). After considering public comments from stakeholders and interested parties, DOE proposes to adopt a standby loss test for unfired storage tanks that is based, in part, on existing industry test methods (

i.e.,

GAMA Testing Standard IWH-TS-1 (March 2003 edition)). Energy conservation standards for unfired hot water storage tanks will remain in terms of the current insulation R-value requirement until DOE completes a future rulemaking to establish standards in terms of the proposed standby loss metric, presuming such metric is adopted in the test procedure final rule. This proposed standby loss test method is discussed in detail in section III.C.

Another issue raised by DOE in the February 2014 RFI regarded the method of setting the tank thermostat prior to conducting the thermal efficiency test. 79 FR 10999, 11002-03 (Feb. 27, 2014). The current Federal test procedure at 10 CFR 431.106 references Exhibits G.1 and G.2 of ANSI Z21.10.3-2011, which requires water heaters to achieve a maximum mean tank temperature of 140 °F ± 5 °F after the thermostat reduces the gas supply to a minimum. However, some CWH equipment may experience difficulty in attaining a mean tank temperature of 140 °F ± 5 °F due to the design of the heat exchanger and positioning of the thermostat sensor. Such systems may in fact be able to supply water at a temperature of 140 °F ± 5 °F, but yet not meet the mean tank temperature requirement. As a result, DOE proposes to modify the test procedure for gas-fired and oil-fired storage water heaters and storage-type instantaneous water heaters to use the outlet water temperature as the set point for setting the thermostat, rather than the mean tank temperature. This change would still ensure the water heater provides water at the specified temperature, while accommodating models that are not designed to have high mean tank temperatures (

i.e.,

condensing water heaters) or that rely upon stratification. The set point temperature value would remain the same at 140 °F ± 5 °F. However, for electric storage water heaters, DOE proposes to maintain a mean tank temperature requirement for the standby loss test because of complications with setting the thermostats for each electric heating element. Specifically, it is unclear how each thermostat could be set to provide a designated outlet water temperature in a way that would differ from the method used for a mean tank temperature requirement. Additional discussion of this issue is contained in section III.D.

In the February 2014 RFI, DOE requested information on whether any clarifications are needed in the thermal efficiency test procedure to indicate water flow requirements or to account for changes in thermal energy stored within the water heater during the duration of the test. 79 FR 10999, 11003 (Feb. 27, 2014). Based on the comments received, DOE has tentatively concluded that the current test procedure prescribed in 10 CFR 431.106 does not require any amendment to account for changes in stored thermal energy or water flow requirements during the thermal efficiency test method. The existing test procedure requires the water heater to attain steady-state conditions with no variation of outlet water temperature in excess of 2 °F over a period of 3 minutes. Once steady-state conditions are achieved, the internal tank temperature maintains a constant value, indicating that the stored energy in the water heater remains constant as long as the firing rate remains constant. While DOE has tentatively concluded that an amendment to account for stored energy changes is not needed, DOE proposes to introduce a statement clarifying that during the thermal efficiency test, the burner must continuously fire at the full firing rate (

i.e.,

no modulation or cut-outs) for the entire duration of the thermal efficiency test, and the outlet water temperature must be maintained at 70 °F ± 2 °F above the supply water temperature. DOE also proposes to clarify that during the thermal efficiency and standby loss tests, no settings on the water heating equipment can be changed until measurements for the test have finished. Additional discussion of these issues is contained in section III.E.

In this NOPR, DOE proposes several changes to the definitions included in the regulations for consumer water heaters at 10 CFR 430.2 and for CWH equipment at 10 CFR 431.102. For consumer water heaters, DOE proposes to remove exemptions from the definitions that exclude units that heat water to temperatures greater than 180 °F and units with a storage capacity greater than 120 gallons. DOE also proposes to remove the definitions for consumer “electric heat pump water heater” and “gas-fired heat pump water heater.” DOE proposes the following changes to the definitions for CWH equipment: (1) Replacing all mentions of the terms “input rating” or “rated input” with the term “fuel input rate” in the context of gas-fired or oil-fired CWH equipment, based on the proposed changes regarding fuel input rate that are further discussed in section III.K; (2) modifying DOE's definitions for “instantaneous water heater” and “storage water heater” by adding the input criteria that separate consumer water heaters and commercial water heaters and removing several phrases that do not serve to clarify coverage of units under the definitions; and (3) removing the definition of “packaged boiler.” DOE also proposes to modify the definition for “residential-duty commercial water heater” by removing from its scope the following classes, for which the input criteria indicating

residential application do not allow classification of any units: electric storage water heaters, heat pump water heaters with storage, gas-fired instantaneous water heaters, and oil-fired instantaneous water heaters. Additional discussion of these proposed changes to DOE's definitions for consumer water heaters and CWH equipment is provided in section III.F.

Water heaters with storage tanks and submerged fire-tube heat exchangers that have input ratings above 4,000 Btu/h per gallon of water stored are currently classified as instantaneous water heaters and hot water supply boilers with a storage volume greater than or equal to 10 gallons. However, DOE believes that these units that are equipped with storage tanks are fundamentally different from other instantaneous water heaters, and, therefore, the Department proposes to define the term “storage-type instantaneous water heater.” DOE also proposes that such units would be tested according to the same method as used for commercial storage water heaters. Additional discussion of these issues are contained in section III.F.4.

Instantaneous water heaters and hot water supply boilers are covered equipment subject to the current Federal test procedure as set forth in 10 CFR 431.106. In response to the February 2014 RFI, AHRI raised an issue with regards to the applicability of the standby loss test procedure described in Exhibit G.2 of ANSI Z21.10.3-2011 for instantaneous water heaters and hot water supply boilers that have no means of initiating burner operation without an active flow of water through the equipment. Additionally, ANSI Z21.10.3-2015 was updated from previous versions of the industry testing standard to include a new test method for measuring the standby loss of tube-type instantaneous water heaters, which AHRI recommended DOE use for determining the standby loss of such instantaneous water heaters and hot water supply boilers. DOE identified numerous problematic issues with this procedure and tentatively decided not to incorporate it by reference in its test procedures for CWH equipment. (The AHRI comments and this test method are discussed it in greater detail, along with DOE's proposed standby loss test procedure for flow-activated instantaneous water heaters, in section III.G.) The current standby loss test procedure involves shutting off the flow of water through the water heater and calculating the amount of energy required to raise the internally stored water temperature to a thermostatically-set value when it drops to a point at which it needs to be reheated. For such a test, it is assumed that when the stored water reaches the minimum allowable water temperature (below the thermostat set point) a control signal activates that will initiate the next firing or heating cycle. This is true for most CWH equipment; however, flow-activated instantaneous water heaters require flow of water through the heater to initiate the next firing or heating cycle. In these designs, if there is no continuous water flow, the next firing or heating cycle is not triggered even if the temperature of hot water inside the heater falls below the thermostat set point. To address this issue, DOE proposes to adopt a separate standby loss test for flow-activated instantaneous water heaters. DOE currently only prescribes standby loss standards for gas-fired and oil-fired instantaneous water heater and hot water supply boilers with a storage capacity greater than or equal to 10 gallons. The proposed test method would apply to all units that meet the proposed definition for “flow-activated instantaneous water heater,” and is described in detail in section III.G.

The current thermal efficiency and standby loss test method requires the water heater to be set up as per Figure 2 in ANSI Z21.10.3-2011, which is identical to Figure 3 in ANSI Z21.10.3-2015. Although the figures provide an unscaled pictorial arrangement of the test set up, neither Figure 2 in ANSI Z21.10.3-2011 nor Figure 3 in ANSI Z21.10.3-2015 specifies the exact location of the outlet water temperature measurement. DOE understands that this unspecified location for outlet water temperature measurement could lead to inconsistent test results and an inaccurate representation of the actual outlet water temperature, especially if the outlet water temperature represents the internal stored water temperature for instantaneous water heaters and hot water supply boilers (as proposed in this NOPR and discussed in section III.G and III.I). Moreover, the temperature-sensing installations, as set forth in Annex E.1 of ANSI Z21.10.3-2015, do not provide clear instructions for installing temperature-sensing means for instantaneous water heaters and hot water supply boilers. Considering the issues related to temperature measurement for instantaneous water heaters and hot water supply boilers, DOE proposes to specify the temperature-sensing location for the outlet water temperature such that the tip or junction of the sensor is less than or equal to 5 inches away from the water heater jacket and requirements for placement of the temperature-sensing probe in the water line for both supply and outlet water measurement. In addition to this issue, DOE also proposes to add supply and outlet water valves at locations closer to the water heater. Specifically, DOE proposes to add a supply water valve within a distance of 5 inches from the water heater jacket and an outlet water valve within a distance of 10 inches from the water heater jacket. Currently, the test set up does not clearly indicate the location of the water supply valves. These valves would be turned off at the start of the standby loss test for instantaneous water heaters and hot water supply boilers (as proposed in this NOPR and discussed in section III.G and III.I). DOE also proposes to add provisions for outlet water temperature measurement and placement of water valves for instantaneous water heaters and hot water supply boilers that have multiple supply and outlet water connections and that are shipped with piping installed by the manufacturer. Finally, DOE proposes to clarify the conditions for using a re-circulating loop. The proposed provisions are similar to those specified in ANSI Z21.10.3-2011 (and ANSI Z21.10.3-2015), and further details on this issue are contained in section III.H.

In response to the RFI, manufacturers also raised the issue of the applicability of the current Federal standby loss test procedure to instantaneous water heaters and hot water supply boilers that are not tank-type water heaters and that have a storage capacity of ten gallons or more (all comments on this topic are discussed in section III.I of this NOPR). The Federal standby loss test procedure in 10 CFR 431.106 incorporates by reference Exhibit G.2 of ANSI Z21.10.3-2011, which requires the measurement of mean tank temperature to calculate standby loss. Instantaneous water heaters and hot water supply boilers generally are not equipped with an integral storage tank, but rather the stored water is contained within the heat exchanger. Therefore, measuring the mean tank temperature for such type of equipment would not be possible (as a storage tank does not exist). Moreover, due to the complex geometry and design of the heat exchangers of such equipment, obtaining an accurate value of the mean stored water temperature inside the heat exchanger would be difficult, or in some cases, may be impossible. To address this issue, DOE proposes to use the outlet water temperature as a conservative estimate for the mean tank temperature. This approach is similar to that used for the standby loss test for

flow-activated water heaters and would be significantly less burdensome than using other means to accurately measure the stored water temperature inside the heat exchanger. Additional details on this test procedure are provided in section III.I.

In the February 2014 RFI, DOE also requested comments on development of a test procedure for commercial heat pump water heaters (CHPWHs). 79 FR 10999, 11003 (Feb. 27, 2014). Based on the comments received, DOE proposes to incorporate by reference ANSI/ASHRAE Standard 118.1-2012,

Method of Testing for Rating Commercial Gas, Electric, and Oil Service Water-Heating Equipment

(ANSI/ASHRAE Standard 118.1-2012) to use as the basis for the Federal CHPWH test method, with several modifications discussed in further detail in III.J. DOE also proposes to adopt rating conditions for four categories of CHPWHs: (1) Air-source CHPWHs; (2) direct geo-exchange CHPWHs; (3) ground water-source CHPWHs; and (4) indoor water-source CHPWHs. The proposed rating conditions are based on ANSI/AHRI Standard 1300 (I-P)-2013:

Performance Rating of Commercial Heat Pump Water Heaters.

Additional discussion of this proposed test procedure is contained in section III.J.

In its current regulations for CWH equipment in subpart G to 10 CFR part 431, DOE includes several terms referring to the input capacity, and does not include any method for determining or verifying the input capacity during testing. In this NOPR, DOE proposes to define “fuel input rate” for gas-fired and oil-fired CWH equipment and proposes a procedure for calculating the fuel input rate during the thermal efficiency test. DOE proposes that the gas consumption be measured every 10 minutes, and that the calculated fuel input rates for each 10-minute interval of the thermal efficiency test cannot vary by more than ± 2 percent between each reading. DOE also proposes means to verify the fuel input rate. Additional discussion of these proposed changes regarding fuel input rate is contained in section III.K.

In this NOPR, DOE proposes several changes to its certification requirements at 10 CFR part 429. First, DOE proposes to add requirements to 10 CFR 429.44 that manufacturers must certify whether gas-fired and oil-fired instantaneous water heaters and hot water supply boilers contain submerged heat exchangers, so that such models can be classified under DOE's proposed definition for “storage-type instantaneous water heaters.” Second, DOE proposes to require manufacturers to certify whether instantaneous water heaters and hot water supply boilers require flow through the water heater to initiate burner ignition. Further discussion of these proposed changes are included in section III.M. Additionally, DOE proposes default values for these parameters to be used in testing if the parameters are not reported in manufacturer literature shipped with the equipment or the supplemental test instructions. Further discussion of these proposed default values are included in section III.L.

In any rulemaking to amend a test procedure, DOE must determine to what extent, if any, the proposed test procedure would alter the measured energy efficiency of any covered product as determined under the existing test procedure. (42 U.S.C. 6293(e)(1); 42 U.S.C. 6314(a)(4)(C)) DOE expects that the proposed changes to the test procedure will not significantly alter the efficiency ratings for a most classes of CWH equipment. There could, however, be changes to the measured energy efficiency for unfired hot water storage tanks. If DOE adopts the changes to the existing test procedures proposed in this NOPR for those products, then DOE will establish energy conservations standards for unfired hot water storage tanks in terms of a new standby loss metric in a separate rulemaking, and the test procedure changes related to unfired hot water storage tanks will not apply until compliance is required with the new standards. DOE also proposes a new test procedure for measuring standby loss of flow-activated instantaneous water heaters with a storage capacity greater than or equal to 10 gallons. However, DOE does not believe this proposed test procedure will affect the measured energy efficiency of flow-activated instantaneous water heaters.

III. Discussion

In response to the February 2014 RFI, DOE received eight written comments from the following interested parties: Bradford White Corporation (Bradford White); A.O. Smith Corporation (A.O. Smith); HTP, Inc. (HTP); Rheem Manufacturing Company (Rheem); Edison Electric Institute (EEI); Air-Conditioning, Heating, and Refrigeration Institute (AHRI); American Public Power Association (APPA); and the American Council for an Energy-Efficient Economy (ACEEE) and National Resources Defense Council (NRDC), who filed a joint comment (henceforth referred to as “Joint Advocates”). These interested parties commented on a range of issues, including those identified by DOE in the February 2014 RFI, as well as several other pertinent issues. The issues, the comments received, DOE's responses to those comments, and the resulting proposed changes to the test procedures for CWH equipment, are discussed in the following subsections.

Updated Industry Test Methods

DOE's test procedure for measuring the energy efficiency for CWH equipment currently incorporates by reference the industry standard ANSI Z21.10.3-2011 at 10 CFR 431.105. Additionally, DOE lists ASTM Standard Test Methods D2156-80, C177-13, and C518-10 as sources of information and guidance in 10 CFR 431.104. DOE defines “ASTM Standard Test Method D2156-80” at 10 CFR 431.102, and points to this source in DOE's current test procedure at 10 CFR 431.106. DOE points to ASTM C177-13 and ASTM C518-10 in its definition for “R-value” at 10 CFR 431.102. The following subsections discuss proposed revisions to DOE's test procedure for CWH equipment vis-à-vis these industry standards.

1. ANSI Z21.10.3 Testing Standard

As noted above, DOE's test procedure for measuring the energy efficiency for CWH equipment currently incorporates by reference the industry standard ANSI Z21.10.3-2011 at 10 CFR 431.105. Specifically, the DOE test procedures at 10 CFR 431.106 directs one to follow Exhibits G.1 and G.2 of ANSI Z21.10.3-2011 for measuring thermal efficiency and standby loss, respectively. An updated edition of the industry test method, ANSI Z21.10.3-2013/CSA 4.3-2013, was approved on March 25, 2013, and released in July 2013.

In the February 2014 RFI, DOE requested feedback on the appropriateness of replacing references to ANSI Z21.10.3-2011 with equivalent references to ANSI Z21.10.3-2013 (which, at that time, was the most current industry testing standard). 79 FR 10999, 11001-02 (Feb. 27, 2014). All parties that commented on this issue agreed with DOE that ANSI Z21.10.3-2013 was an appropriate replacement for ANSI Z21.10.3-2011. (Bradford White, No. 8 at p. 1;

Rheem, No. 3 at p. 1; HTP, No. 5 at pp. 1-2; A.O. Smith,

No. 7 at p. 1; Joint Advocates, No. 4 at p. 1; and AHRI, No. 2 at p. 1)

A notation in this form provides a reference for information that is in the docket of DOE's rulemaking to develop test procedures for commercial water heating equipment (Docket No. EERE-20014-BT-TP-0008), which is maintained at

www.regulations.gov

. This notation indicates that the statement preceding the reference is document number 8 in the docket for the test procedure rulemaking for commercial water heating equipment, and appears at page 1 of that document.

However, since publication of the February 2014 RFI, ANSI updated its test method twice. First, an updated version was approved on July 2, 2014, and released in August 2014—ANSI Z21.10.3-2014/Canadian Standards Association (CSA) 4.3-2014,

Gas-fired Water Heaters, Volume III, Storage Water Heaters with Input Ratings Above 75,000 Btu Per Hour, Circulating and Instantaneous

(hereinafter referred to as “ANSI Z21.10.3-2014”). Another updated version was then approved on October 5, 2015, and released in November 2015—ANSI Z21.10.3-2015/CSA 4.3-2015,

Gas-fired Water Heaters, Volume III, Storage Water Heaters with Input Ratings Above 75,000 Btu Per Hour, Circulating and Instantaneous

(hereinafter referred to as “ANSI Z21.10.3-2015”). DOE reviewed ANSI Z21.10.3-2015 and compared it with ANSI Z21.10.3-2011, and found one significant difference between the sections of the test method that DOE currently references in its test procedures for CWH equipment (

i.e.,

Exhibits G.1 and G.2 of ANSI Z21.10.3-2011) and those contained in ANSI Z21.10.3-2015 (

i.e.,

Annexes E.1 and E.2). In Exhibit G.2 of ANSI Z21.10.3-2011, the current DOE test procedure, the equation for standby loss `S' is presented as:

EP09MY16.267

In Annex E.2 of ANSI Z21.10.3-2015, the equation is exactly the same, except that the Δ

term in the denominator of the second term of the equation is replaced by Δ

. Based on the definitions for the terms provided in both ANSI Z21.10.3-2011 and ANSI Z21.10.3-2015, Δ

refers to the difference between the average value of the mean tank temperature and the average value of the ambient room temperature expressed in °F. The term Δ

is defined as the difference between the final and the initial mean tank temperature.

DOE has tentatively concluded that the standby loss equation provided in ANSI Z21.10.3-2011 (and ANSI Z21.10.3-2013) is appropriate. If the Δ

term is replaced with the Δ

term in the second term of the standby loss equation as specified by ANSI Z21.10.3-2015, then the term Δ

would cancel out, and the equation will not include the temperature difference between the final and initial mean tank temperature that corresponds to the heat lost by the water heater during the course of the test. Therefore, DOE proposes to adopt as part of appendices A and B to subpart G of part 431 the standby loss equation as specified in Exhibit G.2 of ANSI Z21.10.3-2011 (and also included in ANSI Z21.10.3-2013) for calculating the standby loss of all storage water heaters and storage-type instantaneous water heaters. DOE also proposes to re-arrange the terms of the equation to improve the readability of the equation, and remove the gas consumption term for electric water heaters. For instantaneous water heaters and hot water supply boilers other than storage-type instantaneous water heaters, DOE proposes separate standby loss test procedures and equations in sections III.G and III.I.

DOE did not find any other substantive differences between Exhibits G.1 and G.2 of ANSI Z21.10.3-2011 and Annexes E.1 and E.2 of ANSI Z21.10.3-2015. Therefore, DOE proposes to incorporate by reference Annex E.1 of ANSI Z21.10.3-2015 in its proposed test procedures for CWH equipment. DOE does not propose to incorporate by reference Annex E.2 of ANSI Z21.10.3-2015; however, DOE has included certain language from Annex E.2 in its standby loss test procedures proposed in this NOPR.

ANSI Z21.10.3-2015 also includes a new efficiency test procedure—Annex E.3, “Method of test for measuring standby loss for tube type instantaneous water heaters with 10 or greater gallons of storage.” This procedure provides a method to test standby loss of instantaneous water heaters and hot water supply boilers, including those that require flow of water to activate the burner or heating element (

i.e.,

“flow-activated instantaneous water heaters”). DOE reviewed this test procedure, and it is discussed in further detail in section III.G, where DOE proposes a new standby loss test procedure for flow-activated instantaneous water heaters.

DOE also proposes a procedure similar to that specified in section 5.27 of ANSI Z21.10.3-2015 for determining the storage volume of CWH equipment. DOE's proposed language only includes clarifying differences from the language in section 5.27 of ANSI Z21.10.3-2015, and DOE believes that the clarifying differences would not affect conduct of the test procedure between DOE's proposed procedure and the method included in section 5.27 of ANSI Z21.10.3-2015. DOE's proposed procedure for determining storage volume is discussed in further detail in section III.G.

2. ASTM Standard Test Method D2156

DOE's current test procedure for oil-fired CWH equipment at 10 CFR 431.106 points to ASTM Standard Test Method D2156-80. Specifically, DOE requires that smoke in the flue does not exceed No. 1 smoke as measured by the procedure in ASTM D2156-80. However, there is a more recent version of ASTM D2156 that was approved on December 1, 2009, and reapproved on October 1, 2013. After careful review of D2156-80 and D2156-09, DOE has tentatively concluded that no substantive changes were made between these versions in the test method for determining the smoke spot number. Therefore, DOE proposes to incorporate by reference this newer version, ASTM D2156-09, in its test procedures for oil-fired CWH equipment, in appendices A, C, and E to subpart G of 10 CFR part 431.

DOE's current requirement for smoke spot number of flue gas for oil-fired CWH equipment requires that the smoke in the flue does not exceed No. 1 smoke, but does not specify when during the test to determine the smoke spot number. To improve consistency and repeatability of testing of CWH equipment, DOE is proposing to specify when to conduct the smoke spot test. DOE considered several options for this specification. The first option DOE considered would be to require determination of the smoke spot number after steady-state operation has been achieved, but prior to beginning measurement for the thermal efficiency test. The second option considered would be to require determination of the smoke spot number before and after conduct of the test. The third option considered would be to require determination of the smoke spot number before, after, and during the test. Specifically, in the third option, the

smoke spot number would be determined during the thermal efficiency test 15 minutes after the beginning of the test. This is similar to the requirement to determine the smoke spot number every 15 minutes during the thermal efficiency and combustion efficiency tests that is specified for commercial space heating boilers in AHRI 1500-2015.

After considering these three options and the relative benefits and test burden they might provide, DOE has tentatively concluded that determining the smoke spot number prior to conduct of efficiency testing sufficiently assesses the combustion performance while minimizing test burden for manufacturers. DOE reasoned that it is unlikely for the smoke density to change to a significant extent during a steady-state test if the burner settings are maintained throughout the test. As discussed in section III.E, DOE is also proposing to add a clarifying statement to the test procedure stating that the settings on CWH equipment during the thermal efficiency test are not be changed once steady-state conditions have been established. Therefore, DOE has tentatively concluded that it is not necessary to require determination of the smoke spot number during or after efficiency testing, and rather proposes to require determination of the smoke spot number before beginning measurement for efficiency testing. Specifically, for the thermal efficiency test, DOE proposes to require determination of the smoke spot number after steady-state condition has been reached (as determined by no variation of outlet water temperature in excess of 2 °F over a 3-minute period). For the standby loss test, DOE proposes to require determination of the smoke spot number after the first cut-out before beginning measurements for the standby loss test. DOE also proposes to require that the CO

reading, which is required to be measured when testing oil-fired CWH equipment under DOE's current test procedures specified at 10 CFR 431.106, also be measured at the time required for determination of the smoke spot number.

DOE also proposes to clarify that the smoke spot test and measurement of CO

reading are required before conduct of the thermal efficiency test or standby loss test (as applicable) of oil-fired CWH equipment with one exception. DOE proposes that, if no settings on the water heater have been changed and the water heater has not been turned off since the end of a previously run efficiency test, a second smoke spot test or CO

reading is not required prior to beginning another efficiency test (

i.e.,

thermal efficiency or standby loss).

Additionally, to further clarify the appropriate method for determining the smoke spot number, DOE proposes to adopt specifications to the test procedure for the set-up for measuring the smoke density. Specifically, DOE proposes to require that the smoke measuring device be connected to an open-ended tube, and that this tube must project into the flue

1/4

1/2

of the pipe diameter. These proposed requirements are from the same as those specified for commercial space-heating boilers in AHRI 1500-2015.

Issue 1:

DOE seeks comment on its proposed incorporation by reference of ASTM D2156-09, and on its proposed additional specifications for how to set up the smoke spot test, and when to conduct the smoke spot test and measure the CO

reading.

3. ASTM Test Standards C177-13 and C518-10

DOE's current definition for “R-value” at 10 CFR 431.102 references two industry test methods: ASTM Standard Test Method C177-97 and ASTM Test Standard Method C518-91.

A more recent version of ASTM C177 was approved in September 2013 and published in October 2013 (ASTM C177-13). After careful review, DOE has tentatively concluded that there are no substantive differences in the procedures for measuring R-value between the two versions of ASTM C177. Additionally, a more recent version of ASTM C518 was approved in May 2010 and published in June 2010 (ASTM C518-10). After careful review, DOE has tentatively concluded that there are no substantive differences in the procedures for measuring R-value between the two versions of ASTM C518. Therefore, DOE proposes to incorporate by reference ASTM Standard Test Methods C177-13 and C518-10 and to update its references to these versions in the definition for “R-value” at 10 CFR 431.102.

Issue 2:

DOE seeks comment on its proposed incorporation by reference of ASTM C177-13 and C518-10 for the definition of “R-value.”

Test Method Repeatability and Ambient Test Conditions

As discussed in section III.A of this rulemaking, the DOE test procedure for CWH equipment currently incorporates by reference ANSI Z21.10.3-2011 at 10 CFR 431.105, and DOE proposes to incorporate by reference Annex E.1 of the updated version of the standard, ANSI Z21.10.3-2015, for measuring thermal efficiency and standby loss, respectively.

The test method for thermal efficiency of CWH equipment in Annex E.1 of ANSI Z21.10.3-2015 (and also in Exhibit G.1 of ANSI Z21.10.3-2011) requires that the thermostat be set so that the gas supply is reduced to a minimum, once the mean tank temperature reaches 140 °F ± 5 °F. Then water is supplied continuously to the water heater at a temperature of 70 °F ± 2 °F. The outlet water temperature is adjusted by varying the flow rate until the temperature is constant at 70 °F ± 2 °F above the supply water temperature. After the outlet water reaches steady state, water flow (measured by weight) is recorded for a 30-minute test period, along with supply and outlet water temperatures, the ambient room temperature, and fuel and electricity consumption. These data collected during the 30-minute test period are used to calculate the thermal efficiency.

The standby loss test method in Annex E.2 of ANSI Z21.10.3-2015 (and also in Exhibit G.2 of ANSI Z21.10.3-2011) stipulates that a commercial water heater must be set up as described for the thermal efficiency test and that the unit must be put into operation with the burner gas supply opened. After the first burner cut-out,

the unit is allowed to remain in standby mode until the second burner cut-out, at which point the collection of test data begins. Test data are recorded at 15 minute intervals, and the test ends at either the first cut-out after 24 hours have elapsed, or when 48 hours have elapsed, whichever occurs first. The ambient room temperature, mean tank temperature, fuel and electricity consumption, and time are measured during the test and used to calculate the standby loss.

By “burner cut-out,” DOE refers to when the energy supply to a burner is reduced to a minimum.

In the February 2014 RFI, DOE requested information and data pertaining to the repeatability of thermal efficiency and standby loss test methods included in the ANSI Z21.10.3-2011 and ANSI Z21.10.3-2013 test methods. 79 FR 10999, 11001-02 (Feb. 27, 2014).

HTP commented that the thermal efficiency test is repeatable and is reasonably consistent between testing sites. (HTP, No. 5 at p. 2) No other interested parties provided information on the repeatability of the thermal efficiency test method in ANSI Z21.10.3.

Several parties provided comments regarding the repeatability of the standby loss test method. HTP commented that the standby loss test

method produces data with significant lab-to-lab variation in test results and attributed this variation to the physics of the test and the ambient conditions of the test. HTP suggested investigating the effects of stipulating a maximum air draft in the test environment on repeatability of the standby loss test. (HTP, No. 5 at p. 2) HTP and AHRI commented that due to the small amount of energy consumption measured during the standby loss test, the error and variation associated with the tolerances of commercially-available test instrumentation has a larger influence on test results, resulting in a greater degree of variance for the standby loss test compared to the thermal efficiency test. (HTP, No. 5 at p. 2 and AHRI, No. 2 at p. 1)

Based on these comments from interested parties, DOE investigated various potential test procedure modifications to reduce the variability of results from the test procedures for thermal efficiency and standby loss. In addition, DOE conducted investigative testing that helped inform the proposals discussed in this NOPR. DOE proposes the following seven modifications to the current thermal efficiency and standby loss test procedures, after tentatively determining that these modifications would reduce variation in results: (1) Stipulating a maximum air draft requirement of 50 ft/min as measured prior to beginning the thermal efficiency or standby loss tests; (2) tightening the ambient room temperature tolerance from ±10.0 °F to ±5.0 °F and the allowed variance from mean ambient temperature from ±7.0 °F to ±2.0 °F; (3) requiring measurement of test air temperature—the temperature of entering combustion air—and requiring the test air temperature not vary by more than ±5 °F from the ambient room temperature at any measurement interval during the thermal efficiency and standby loss tests for gas-fired and oil-fired CWH equipment; (4) establishing a requirement for ambient relative humidity of 60 percent ±5 percent during the thermal efficiency and standby loss tests for gas-fired and oil-fired CWH equipment; (5) requiring a soak-in period prior to testing in which the water heater must sit without any draws taking place for at least 12 hours from the end of a recovery from a cold start; (6) specifying the locations of inlet and outlet temperature measurements for storage water heaters, storage-type instantaneous water heaters, and UFHWSTs; and (7) decreasing the time interval for data collection from fifteen minutes to 30 seconds in the thermal efficiency and standby loss tests. While manufacturers cited concerns regarding only the repeatability of the standby loss test in response to comments to the February 2014 RFI, DOE has tentatively concluded that the following proposed modifications would improve the repeatability of both tests. Unless otherwise specified in the following paragraphs, DOE proposes that these changes would apply to thermal efficiency and standby loss tests for all CWH equipment (as applicable).

(1)

Addition of a maximum air draft stipulation, as recommended by HTP.

This modification would allow for more consistent ambient conditions between tests and testing locations, as well as limit the effect of air draft on testing results. DOE proposes to add a requirement that while conducting the thermal efficiency and standby loss tests and during the proposed soak-in period (as applicable), a water heater must be protected from drafts of more than 50 ft/min from room ventilation registers, windows, or other external sources of air movement, to be measured within three feet of the jacket of the water heater. This requirement is similar to the requirement adopted for testing consumer water heaters and certain commercial water heaters in the July 2014 final rule. 79 FR 40542, 40569 (July 11, 2014). DOE notes that Annex E.1 of ANSI Z21.10.3-2015 requires that water heater placement in the test room shall be protected from drafts. This modification simply clarifies the meaning of “protected from drafts” by setting a requirement for the maximum allowable draft during the test. DOE proposes that the air draft be measured prior to beginning the soak-in period and thermal efficiency and standby loss tests, and that no actions can be taken during the conduct of the tests or the soak-in period that would increase the air draft near the water heater being tested.

(2)

A decrease in the allowed maximum variance for ambient room temperature for both the thermal efficiency and standby loss tests.

The current test procedure at 10 CFR 431.106 references Exhibits G.1 and G.2 of ANSI Z21.10.3-2011, which require that the ambient room temperature be maintained at 75 °F ± 10 °F, and that the ambient room temperature not vary by more than ±7 °F from the average ambient room temperature during the test. DOE proposes requiring that the ambient room temperature be maintained at 75 °F ± 5 °F and that the room temperature not vary by more than ±2.0 °F from the average ambient room temperature while setting thermostats and verifying steady-state operation, between the first and second cut-outs prior to the standby loss test (as applicable), and during the thermal efficiency and standby loss tests and proposed soak-in period (as applicable) for all CWH equipment.

(3)

Addition of a requirement for measurement of test air temperature for gas-fired and oil-fired commercial water heating equipment.

DOE understands that the entering air temperature can have a significant impact on combustion in gas-fired and oil-fired CWH equipment. To improve repeatability of the thermal efficiency and standby loss tests for these classes of equipment, DOE proposes to require measurement of test air temperature, within 2 feet of the air inlet to the water heater. For CWH equipment that does not have a specific air inlet, DOE proposes that the test air temperature be measured within 2 feet of the jacket of the water heater closest to where air would be drawn for combustion. DOE also proposes a requirement that the test air temperature may not vary by more than ±5 °F from the ambient room temperature at any measurement interval during the course of the thermal efficiency or standby loss tests (as applicable) or while establishing steady-state operation prior to the thermal efficiency test for gas-fired and oil-fired CWH equipment. For units with multiple air inlets, DOE proposes that the test air temperature must be measured at each air inlet, and that the specified tolerance on deviation from the ambient room temperature must be maintained at each air inlet. This required tolerance for test air temperature was modeled after AHRI 1500-2015 in order to remain consistent with common industry practices. However, DOE proposes that this test air temperature requirement not apply to the standby loss test for flow-activated instantaneous water heaters proposed in section III.G of this NOPR, because the burner will not activate during the test. DOE also does not propose a test air temperature requirement for electric water heaters because electric water heaters are not powered by combustion, and, therefore, the test air temperature does not affect the efficiency of the heating elements.

(4)

Establishment of a requirement for ambient relative humidity of 60 percent ±5 percent for gas-fired and oil-fired commercial water heating equipment.

DOE understands that humidity can have a significant effect on the tested efficiency of gas-fired and oil-fired CWH equipment, particularly condensing equipment. High humidity would enable equipment to capture more latent heat from combustion gases, thereby resulting in a higher measured

efficiency. Therefore, the lack of a specification for ambient humidity in DOE's current test procedures for gas-fired and oil-fired CWH equipment can lead to variation in test results between test labs. DOE recognizes that this effect would be noticeable in tests for both thermal efficiency and standby loss. Therefore, DOE proposes to amend its test procedures by specifying a requirement that ambient relative humidity be set and maintained at 60 percent ±5 percent for gas-fired and oil-fired CWH equipment while verifying steady-state operation and during the thermal efficiency and standby loss tests, so as to minimize this effect, which should reduce variability in test results. However, DOE proposes that this ambient humidity requirement not apply to the standby loss test for flow-activated instantaneous water heaters proposed in section III.G of this NOPR, because the burner will not activate during the test. DOE also does not propose an ambient humidity requirement for electric water heaters because electric water heaters are not powered by combustion and, therefore, the ambient air humidity does not affect the efficiency of the heating elements. Also, DOE proposes that the ambient relative humidity be measured and recorded at the same location as the test air temperature, and at 30-second intervals during the entire test. For units with multiple air inlets, DOE proposes that the ambient relative humidity must be measured at each air inlet, and that 60 percent ±5 percent must be maintained at each air inlet. DOE proposes that the ambient relative humidity must remain within the specified range at all times during conduct of the thermal efficiency and standby loss tests.

(5)

Addition of a requirement to perform a pre-test conditioning phase, also known as a soak-in period, for storage water heaters and storage-type instantaneous water heaters.

This proposed provision would require that the water heater remain idle (

i.e.,

no water draws) for at least 12 hours with the thermostats maintained at settings that would achieve the required water temperature (see section III.D for further detail on proposed requirements for setting the tank thermostat), prior to conducting either a thermal efficiency test or standby loss test. This modification is similar to the soak-in period requirement adopted for consumer water heaters and certain commercial water heaters in the July 2014 final rule. 79 FR 40542, 40571 (July 11, 2014). This requirement would help minimize transient heat transfer effects that may reduce the reproducibility of the current standby loss test. However, DOE proposes not to require a soak-in period be conducted prior to beginning an efficiency test (

i.e.,

thermal efficiency or standby loss) if no settings on the water heater have been changed and the water heater has not been turned off since the end of a previously run efficiency test. DOE proposes a requirement for a soak-in period for unfired hot water storage tanks with different test conditions in section III.C.

(6)

Specifying the locations for inlet and outlet water temperature measurement for storage water heaters, storage-type instantaneous water heaters, and unfired hot water storage tanks.

DOE's current test procedure for CWH equipment incorporates by reference the requirement in Exhibit G.1 of ANSI Z21.10.3-2011 that the inlet and outlet piping be immediately turned vertically downward from the connections on a tank-type water heater to form heat traps and that the thermocouples for measuring inlet and outlet water temperatures be installed before the inlet heat trap piping and after the outlet heat trap piping. While DOE agrees with the general position of the inlet and outlet thermocouples relative to the heat trap piping, the precise location of the thermocouples in terms of distance away from the water heater is not specified. The absence of a clearly defined location for the thermocouples can contribute to variability in the test results. Considering this issue, DOE proposes that the thermocouples be placed with total vertical piping length of 24 inches. For water heaters with vertical connections, the 24 inches of total vertical piping distance is divided into 6 inches of vertical piping upstream from the turn for the heat trap and 18 inches downstream from the turn for the heat trap. For water heaters that have horizontal water connections, DOE proposes that the thermocouples be placed with total horizontal piping length between the thermocouple location and the connection port of six inches. For water heaters that have vertical water connections, due to the differences in the size and dimensions of water heaters, it may not be possible to have the inlet and outlet water piping be turned vertically downward after a fixed horizontal distance of 6 inches away from the connection port. Therefore, for water heaters with vertical connections (opening top or bottom), DOE proposes that the horizontal distance be equal to the distance from the connection port to the edge of the water heater plus 2 inches. Figure III.1, Figure III.2, and Figure III.3 show the three proposed configurations for placement of inlet and outlet water thermocouples for tank-type water heaters. All dimensions shown in the figures and specified in this paragraph are measured from the outer surface of the pipes or water heater jacket (as applicable).

BILLING CODE 6450-01-P

EP09MY16.268

EP09MY16.269

BILLING CODE 6450-01-C

(7)

Increasing the frequency of data collection.

To further reduce variability in test results, DOE proposes to decrease the length of the time interval between data collection during the thermal efficiency test from 1 minute to 30 seconds and during the standby loss test from 15 minutes to 30 seconds for all CWH equipment (as applicable). This time interval would apply to the measurement of ambient room temperature, test air temperature, and ambient relative humidity for both the thermal efficiency and standby loss tests (as applicable). For the thermal efficiency test, the 30-second time interval would also apply to the measurement of supply and outlet water temperatures. For the standby loss test the 30-second time interval would apply to the measurement of mean tank temperature for storage and storage-type instantaneous water heaters (storage-type instantaneous water heaters are discussed in section III.F), and to measurement of outlet water temperature for instantaneous water heaters and hot water supply boilers. Additionally, DOE proposes that the fuel (

i.e.,

gas or oil) consumption be measured at 10-minute intervals during the thermal efficiency test. These increases in frequency of data collection would increase data granularity, thereby providing more information to identify testing irregularities contributing to test result variance. This modification would also allow for more accurate timing of test start and stop, which may lead to more repeatable results.

DOE also considered three other modifications to improve standby loss test repeatability, but ultimately decided against proposing these modifications for the reasons provided. The three additional considered but rejected modifications include:

(1)

An increase in the number of temperature sensors measuring internal tank temperature from six to twelve.

These sensors would be located at the vertical midpoint of 12 equal volumes of water within the water heater. It was thought that this modification could potentially increase the reliability of the internal tank temperature data and allow better resolution of temperature stratification within the tank. However, based on preliminary test data, DOE observed that increasing the number of sensors had little effect on the outcome of the test and, thus, does not justify the additional burden.

(2)

An increase in the number of thermal probes used to measure ambient temperature from one to at least four.

These probes could be located at the vertical midpoint of the tank at a perpendicular distance of 24 inches (61 cm) from the surface of the jacket, and in each cardinal direction (

i.e.,

North, South, East, and West). It was thought that this modification could potentially help reduce uncertainty of the true ambient temperature profile around the water heater and the associated effect of this uncertainty on the measured standby loss of tested CWH equipment. However, based on preliminary test data, DOE observed that increasing the number of sensors had little effect on the ambient temperature readings, and, thus, little impact on the outcome of the test. Consequently, it would not justify the additional burden.

(3)

Lengthening the required period for establishing steady-state operation prior to the thermal efficiency test to thirty minutes.

DOE's current test procedure references Exhibit G.1 of ANSI Z21.10.3-2011, which requires that the outlet water temperature be established as constant prior to conducting the thermal efficiency test, as determined by no variation in excess of 2 °F over a 3-minute period. For some equipment, a 3-minute period may not be long enough to establish steady-state operation of gas-fired or oil-fired CWH equipment, and a water heater could conceivably exhibit no variation in excess of 2 °F over a 3-minute period before establishing steady-state operation. Additionally, DOE notes that the current test procedure does not impose requirements for maximum variation in inlet water temperature or water flow rate during this period for verifying steady-state operation. Thus, DOE believes that extending the period for determining steady-state operation could improve test method repeatability, and DOE is seeking information and data regarding such a change. DOE notes that for commercial packaged boilers, which are similar equipment to some classes of CWH equipment, AHRI 1500-2015 specifies a 30-minute warm-up period for determining steady-state operation has been achieved.

Issue 3:

DOE requests comments and data on its proposed changes to improve the repeatability of the thermal efficiency and standby loss test procedures for certain commercial water heating equipment. Specifically, DOE requests comment on its proposed requirements for ambient relative humidity. DOE does not propose this requirement for testing of electric water heaters, and seeks feedback on whether including such a requirement would improve the repeatability of the standby loss test for electric water heaters. DOE is also seeking comments regarding any additional changes that would improve the repeatability of the thermal efficiency and standby loss tests.

Issue 4:

DOE requests comment on the changes to improve test repeatability for its test procedures for certain CWH equipment that were identified but not proposed in this NOPR. If comments suggest that DOE should implement these changes, then DOE will evaluate whether it can adopt those changes in the final rule or must engage in further rulemaking. Particularly, DOE requests data showing what duration for the steady-state verification period would ensure steady-state operation is reached for gas-fired and oil-fired CWH equipment prior to the thermal efficiency test. DOE also seeks data that suggest suitable tolerances for water temperature and flow rate for this steady-state verification period. Additionally, DOE seeks comment on whether different requirements for establishing steady-state operation are warranted for each equipment class of CWH equipment.

Test Method for Unfired Hot Water Storage Tanks

EPCA defines an “unfired hot water storage tank” (UFHWST) as a tank used to store water that is heated externally. (42 U.S.C. 6311(12)(C)) The current Federal standard for this equipment type requires a minimum thermal insulation (R-value) of 12.5. 10 CFR 431.110. DOE defines “R-value” as the thermal resistance of insulating material as determined based on ASTM Standard Test Method C177-97 or ASTM Standard Test Method C518-91 and expressed in °F·ft

·h/Btu. 10 CFR 431.102. In section III.A.3 of this rulemaking, DOE proposes to update references to these standards in its definition for “R-value” by incorporating by reference ASTM C177-13 and ASTM C518-10.

DOE is aware that some manufacturers ship UFHWSTs without insulation, and that uninsulated UFHWSTs may or may not then be insulated on-site. In this rulemaking, DOE makes clear that UFHWSTs shipped without insulation are not compliant with the Federal R-value standard. All UFHWSTs must either be shipped insulated to the R-value standard or shipped together with insulation meeting the R-value standard. Manufacturers of UFHWSTs must certify that the insulation meets the R-value standard prescribed in 10 CFR 431.110, and this certification must be based on testing according to the methods prescribed in the R-value definition. A UFHWST manufacturer may demonstrate compliance with the insulation requirements either by

conducting testing itself or by using test data from the insulation material producer. Further, manufacturers of UFHWSTs are responsible for retaining records of the underlying test data used for certification in accordance with current maintenance of records requirements set forth at 10 CFR 429.71.

Because DOE includes ASTM test methods for measuring R-value in its definition of “R-value,” DOE does not currently specify a test procedure for measuring energy efficiency of UFHWSTs in 10 CFR 431.106. In the February 2014 RFI, DOE requested comment on whether the R-value is an adequate energy efficiency descriptor for UFHWSTs. DOE also requested comment on the potential for replacing R-value with standby loss, or another metric, as the energy efficiency descriptor for UFHWSTs, and how to establish a standby loss test or other test for this equipment if such a metric is appropriate. 79 FR 10999, 11002 (Feb. 27, 2014).

A.O. Smith, AHRI, and Rheem commented that there is no need for a test procedure to measure the R-value of the insulation on UFHWSTs. (A.O. Smith, No. 7 at pp. 1-2; AHRI, No. 2 at pp. 2-3; Rheem, No. 3 at pp. 1-2) AHRI also commented that the R-value requirement is in no way a measurement of the “efficiency” of an unfired storage tank, and that ASHRAE deliberately did not include a thermal efficiency or standby loss requirement for this equipment in ASHRAE Standard 90.1. (AHRI, No. 2 at pp. 2-3) Bradford White and HTP support the current requirement of a minimum insulation R-value, and Bradford White estimated that replacing the R-value metric with a metric requiring an efficiency test would require 3 days of testing per model. (Bradford White, No. 8 at p. 1; HTP, No. 5 at p. 2) AHRI, HTP, and Rheem also expressed support for the current two ASTM test methods (C177-97 and C518-91) for testing the R-value of insulation for UFHWSTs. (AHRI, No. 2 at pp. 2-3; HTP, No. 5 at p. 2; Rheem, No. 3 at pp. 1-2)

Joint Advocates noted that the two ASTM test methods are intended for flat samples, while UFHWSTs are generally pressure vessels with curved surfaces. (Joint Advocates, No. 4 at p. 2) Joint Advocates recommended replacing the present R-value requirement for UFHWSTs with a standby loss test similar to the test used for electric and fuel-fired commercial water heaters because the current R-value requirement does not ensure that all surfaces of the tank are adequately insulated, nor does it encourage other methods to reduce heat loss, such as anti-siphon connections and/or eliminating thermal bridges. Joint Advocates also recommended that for any units with legitimate needs for field insulation of UFWHSTs, DOE could either allow for a waiver or establish a separate class of uninsulated UFHWSTs. (Joint Advocates, No. 4 at p. 2)

A.O. Smith and AHRI also pointed out that there exists a group of UFHWSTs that are larger than standard volume models and are often built to order. (A.O. Smith, No. 7 at p. 2; AHRI, No. 2 at pp. 2-3) A.O. Smith and AHRI stated that these units are often shipped without insulation and subsequently field-insulated due to shipping and installation considerations that make it impractical to insulate at the site of manufacture. (A.O. Smith, No. 7 at p. 2; AHRI No. 2 at pp. 2-3)

After considering these comments, DOE has tentatively determined that a measurement of energy efficiency of UFHWSTs is necessary to more fully comply with the requirements of 42 U.S.C. 6314(a)(2)-(3), and proposes a standby loss metric and test method to replace the current R-value requirement. Although DOE recognizes that requiring use of a standby loss test will increase test burden for manufacturers, DOE has tentatively concluded that the benefits of such a metric would outweigh this additional burden. Primarily, DOE agrees with Joint Advocates that a standby loss metric would encourage and credit energy-saving technologies that are not measured by the R-value of the insulation and ensure that all surfaces are adequately insulated. As a result, DOE proposes to establish a standby loss test method for UFHWSTs that monitors the decrease in tank temperature from a set temperature. In addition, DOE proposes to amend the definition of “standby loss” at 10 CFR 431.102 to include unfired hot water storage tanks.

Regarding the points from AHRI, A.O. Smith, and Joint Advocates about UFHWSTs that are shipped without insulation and subsequently field-insulated, DOE reiterates that all UFHWSTs must have a minimum thermal insulation R-value of 12.5 when they are shipped from the manufacturer. Any units shipped without a minimum thermal insulation of R-12.5 and then insulated on-site would not be compliant with DOE's current regulations.

To determine the standby loss of an UFHWST, the storage capacity of the tank must first be determined. Section 5.27 of ANSI Z21.10.3-2015 includes a method for measuring the storage capacity, and it states that this method is applicable to water heaters including storage vessels. DOE examined this method and found no reason why it would be inapplicable to UFHWSTs. Therefore, DOE proposes to use the test method described in section 5.27 of ANSI Z21.10.3-2015 to measure the storage capacity of UFHWSTs. DOE includes a procedure for determining storage volume in its proposed test procedure for UFHWSTs that has only clarifying differences from the method presented in section 5.27 of ANSI Z21.10.3-2015. DOE's proposed procedure for determining storage volume is discussed in further detail in section III.G.

Next, DOE considered three possible test methods to determine the standby loss coefficient and hourly standby losses of an UFHWST. The first method considered—and the one that DOE proposes as the test method for UFHWSTs—is based on a method for assessing the energy efficiency of indirect water heaters, which was originally developed by the GAMA,

and set forth in Testing Standard IWH-TS-1, “Method to Determine Performance of Indirect-Fired Water Heaters” (March 2003 edition).

Under this procedure, the tank is set up as would normally be done in the field, with potable water inlet and outlet piping and supply and return piping connected to an external heat source. This procedure specifies bringing the water in the tank to a mean temperature of 140 °F by the external heat source, and then monitoring the stored water temperature while the heat source is inactive and the water temperature inside the tank decreases. A linear fit is applied to temperature data as the mean tank temperature drops from 137 °F to 133 °F to yield a temperature decay term with units of °F/h. DOE proposes to use this test method as the basis of a test method to determine the standby loss of UFHWSTs but with several modifications. DOE has tentatively concluded that the use of Testing Standard IWH-TS-1 would sufficiently capture the heat loss of UFHWSTs and reduce burden to manufacturers relative to alternative methods, because it is already an industry-accepted procedure that is used in AHRI's certification program for indirect water heaters.

The Air-Conditioning and Refrigeration Institute (ARI) and GAMA merged to become AHRI on January 1, 2008.

Available at:

http://www.org/App_Content/ahri/files/standards%20pdfs/Indirect-Fired%20Water%20Heater%20Testing%20Standard03.pdf

(last accessed February 12, 2015).

As noted in this preamble, DOE proposes several modifications to Testing Standard IWH-TS-1 to be included in DOE's proposed test

procedure for standby loss of UFHWSTs. First, because the nominal tank temperature for determining standby loss for commercial storage water heaters is 140 °F, DOE proposes to calculate standby loss of UFHWSTs using temperature data collected as the mean tank temperature drops from 142 °F to 138 °F instead of 137 °F to 133 °F. To do so, DOE proposes that the tank be filled with water that is heated sufficiently to achieve a mean tank temperature of 145 °F and then be allowed to decrease from that point. Consequently, DOE also proposes to update the water density and specific heat capacity constants used in calculation of standby loss to 8.205 lb/gallon and 0.999 Btu/°F·lb respectively, to correspond to the mid-point of DOE's proposed temperature range (140 °F), instead of the mid-point of the temperature range specified in Testing Standard IWH-TS-1 (135 °F). However, DOE notes that the value for specific heat capacity of water does not change as the temperature increases from 135 °F to 140 °F, with the number of significant figures specified in Testing Standard IWH-TS-1.

DOE also proposes to adopt the same ambient room temperature requirement for all CWH equipment that is discussed in section III.B. Specifically, DOE proposes that the ambient room temperature must be maintained at 75 °F ± 5 °F during the test (as measured at each 30-second interval), and the measured room temperature must not vary by more than ±2.0 °F from the average ambient room temperature during the test. While Testing Standard IWH-TS-1 specifies an ambient room temperature of 70 °F, DOE notes that many manufacturers of UFHWSTs also manufacture storage water heaters. Therefore, DOE expects that manufacturer burden would be reduced if storage water heaters and UFHWSTs can be tested in the same test room, and DOE's proposal is consistent with that objective. Additionally, DOE proposes a requirement for maximum air draft in section III.B that applies to the soak-in period and standby loss test for UFHWSTs. Similar to ambient room temperature, DOE expects that aligning this requirement with that for other classes of CWH equipment will reduce testing burden for CWH manufacturers. DOE also proposes a requirement for a soak-in period to be conducted prior to beginning the standby loss test for UFHWSTs. In this soak-in period, the tank must sit without any draws taking place for at least 12 hours after being filled with water such that a mean tank temperature of 145 °F ± 5 °F is achieved. After completion of the soak-in period, DOE would require that the UFHWST be filled again such that a mean tank temperature of 145 °F ± 5 °F is achieved, because the stored water temperature would decrease during the soak-in period. Additionally, DOE proposes requirements for piping insulation and water supply similar to those for other classes of CWH equipment included in Annex E.1 of ANSI Z21.10.3-2015.

DOE also proposes to collect temperature data at intervals of 30 seconds during this test, as opposed to the 15-minute intervals specified by the IWH-TS-1 test method. DOE has determined that a higher number of data points will improve the accuracy of the least-squares regression and that, given the data storage capacity of modern data acquisition equipment, the higher frequency of data collection will pose only a negligible additional burden upon laboratories, as compared to the current 15-minute data collection interval. DOE also proposes to convert the decay rate metric to the standby loss metric currently applied to commercial storage water heaters, which has units of Btu/h.

DOE also considered two other approaches to determine the standby loss for UFHWSTs and is presenting these alternatives as part of this NOPR for comment on their merits compared to the proposed method. The first alternative is similar to the method proposed, but uses a different condition to end the standby loss test. Specifically, under this approach, the test would end 24 hours after the beginning of the test, instead of after the mean tank temperature reaches a specified temperature. However, the use of such a test ending condition would result in different final water temperatures for units with different rates of heat loss. This variation in final water temperature would impart an undesirable benefit to UFHWSTs that lose heat more quickly, because the rate of heat transfer from water to the surrounding air decreases as the corresponding temperature difference decreases. Additionally, DOE believes that a change in test ending condition to a 24-hour time limit may result in unnecessary test burden for manufacturers, as it would likely extend the duration of the test. In light of the potential downsides to this alternative, DOE has tentatively concluded that the test method proposed in this document (based on the industry-accepted IWH-TS-1 test method) would sufficiently capture the rate of heat loss from the tank while potentially allowing for a shorter test time.

DOE also considered a second alternative test method that would maintain the set point of the hot water within the UFHWST, by connecting an UFHWST to an external heat source (

i.e.,

a water heater or boiler) that would replace water in the tank that has cooled down with water that has been heated by the external source. Circulation from the external heat source to the water heater would be controlled based on the internal tank temperature. The amount of water circulated into the UFHWST from the external source and the temperature of supply water and return water would be monitored during reheat cycles to determine the amount of energy supplied to the tank. This test would start one hour after a reheat cycle and would progress until one hour after completion of the first reheat cycle after 24 hours have elapsed since the start of the test. Calculation of standby loss would include the change in stored energy within the UFHWST, as well as energy supplied to the UFHWST by the external heat source. While this test method would more closely align with DOE's standby loss test procedures for electric and fuel-fired CWH equipment and be more representative of field use of UFHWSTs, DOE has tentatively concluded that this method would be overly burdensome to manufacturers and could lead to increased variability in test results. Use of other CWH equipment to heat water being supplied to the UFHWST could lead to variability based on variation in the equipment and piping used for testing. Based on preliminary test data, DOE observed similar results for a method that uses circulation with an external heat source and a method that does not; therefore, DOE has tentatively concluded that a method using circulation with an external heat source would not provide a more accurate result that would be commensurate with the additional testing burden of such an approach.

Issue 5:

DOE requests comment on the proposed test procedure to determine the standby loss for UFHWSTs, and on whether any other methods, including those detailed in this NOPR, would lead to a better test. Specifically, DOE solicits feedback on whether the proposed test would be long enough to determine an accurate standby loss rating, whether the use of a linear approximation of the temperature decay is sufficient to estimate the standby loss, whether running the test by simply letting the temperature decay (rather than providing external heat to bring the temperature of the water back to operational temperature) is appropriate, and whether the adoption of test

conditions (

i.e.,

ambient room temperature, maximum air draft, water temperature) similar to that of other classes of CWH equipment is appropriate. DOE also seeks comment on whether any of its identified alternatives could be modified to improve their repeatability and to decrease test burden, thereby supporting further consideration.

Procedure for Setting the Tank Thermostat for Storage and Storage-Type Instantaneous Water Heaters

DOE's test method for measuring the energy efficiency of CWH equipment currently requires that the thermostat be set to achieve specific conditions for the mean tank temperature before the test may begin. In particular, section g of Exhibit G.1 of ANSI Z21.10.3-2011 (which is currently incorporated by reference into the DOE test procedure) requires that before starting testing, the thermostat setting must be adjusted such that, when starting with the water in the system at 70 °F ± 2 °F, the maximum mean tank temperature will be 140 °F ± 5 °F after the thermostat reduces the gas supply to a minimum. DOE understands that some units may have difficulty achieving the required mean tank temperature condition, and in the February 2014 RFI DOE requested feedback on potential test procedure amendments to address this issue. 79 FR 10999, 11003 (Feb. 27, 2014).

In response to the February 2014 RFI, the four manufacturers among the interested parties (A.O. Smith, Bradford White, HTP, and Rheem), as well as AHRI, expressed support for changing the set point conditions to require monitoring the outlet water temperature rather than the mean tank temperature. (Bradford White, No. 8 at p. 1; Rheem, No. 3 at p. 2; HTP, No. 5 at p. 2; A.O. Smith, No. 7 at p. 2; AHRI, No. 2 at p. 4) A.O. Smith, Rheem, and AHRI expressed support for maintaining the set point condition at 140 °F ± 5 °F for the outlet water temperature. (A.O. Smith, No. 7 at p. 2; Rheem, No. 3 at p. 2; AHRI, No. 2 at p. 4) A.O. Smith stated that certain designs of CWH equipment cannot reach a mean tank temperature of 140 °F ± 5 °F, including down-fired, condensing equipment with reduced firing rates, and solar or other renewable source equipment. (A.O. Smith, No. 7 at p. 2) DOE received no comments opposing a potential change from setting the thermostat based on the mean tank temperature to setting the thermostat based on the temperature of the delivered water.

After carefully considering these comments, DOE proposes to modify the thermal efficiency and standby loss test procedures for gas-fired and oil-fired storage water heaters and storage-type instantaneous water heaters to require that before starting testing, the thermostat setting be adjusted such that, when starting with the water in the system at 70 °F ± 2 °F, the maximum outlet water temperature will be 140 °F ± 5 °F after the thermostat reduces the gas supply to a minimum. DOE has tentatively concluded that changing from a mean tank temperature requirement to an outlet temperature requirement would better accommodate designs of gas-fired and oil-fired water heaters that are not designed to have high mean tank temperatures (

e.g.,

condensing water heaters) or that rely upon stratification.

DOE does not propose changing the mean tank temperature requirement to an outlet water temperature requirement for electric storage water heaters because of complications with setting tank thermostats. Electric storage water heaters have multiple heating elements and a thermostat corresponding to each element, and each thermostat needs to be set prior to beginning the standby loss test. Therefore, DOE reasons that electric storage water heaters, which vary in configuration and number of heating elements, are not well-suited to an outlet water temperature requirement because it is unclear how the lower thermostats would be set to achieve a designated outlet water temperature. A consistent, reproducible process for setting the thermostats is essential to having a repeatable test. Therefore, DOE proposes to maintain a mean tank temperature requirement for the standby loss test for electric storage water heaters. However, DOE proposes to clarify its language specifying the method for setting thermostats in an electric storage water heater with multiple thermostats. Specifically, DOE proposes to clarify that the thermostats are to be set in immediate succession, starting from the topmost thermostat. DOE also proposes to clarify that when setting each thermostat, the mean tank temperature is calculated using only temperature readings measured at locations higher in the tank than the heating element corresponding to the thermostat being set, with the exception of the bottommost thermostat. Finally, DOE proposes to clarify that all thermostats below the thermostat being tested must be turned off so that no elements below the thermostat being tested are in operation.

Issue 6:

DOE seeks comment on its proposed change to its requirements for setting the tank thermostat in the thermal efficiency and standby loss test procedures for gas-fired and oil-fired storage and storage-type instantaneous water heaters from measurement of mean tank temperature to measurement of outlet water temperature.

Issue 7:

DOE seeks comment on its tentative decision to maintain a mean tank temperature requirement for the standby loss test for electric storage water heaters. DOE also requests comment on its clarifying language for setting tank thermostats for electric storage water heaters with multiple thermostats.

Clarifications to the Thermal Efficiency and Standby Loss Test Procedures

The calculation of thermal efficiency included in the current DOE test procedure for gas-fired and oil-fired CWH equipment at 10 CFR 431.106 (which incorporates the method used in Exhibit G.1 of ANSI Z21.10.3-2011) does not consider change in internal stored energy of the stored water.

In the February 2014 RFI, DOE sought public comment on whether it is necessary to account for the potential variation in stored thermal energy inside the water heater during the course of the test, and specifically whether there is a need to account for losses in the internal stored energy in the thermal efficiency calculation. 79 FR 10999, 11003 (Feb. 27, 2014). In addition, DOE sought feedback on whether there is need for clarification to ensure that the water flow rate is adjusted so that the burner is fired at a constant firing rate or whether cycling of the burner is allowed.

Id.

The thermal efficiency test procedure in Exhibit G.1. of ANSI Z21.10.3-2011 is a steady-state procedure where the supply water temperature is maintained at 70 °F ± 2 °F, outlet water temperature is maintained at 70 °F ± 2 °F above the supply water temperature, and the flow rate is adjusted to a constant value that can maintain these temperatures throughout the duration of the test. Because the supply and outlet water temperatures and the water flow rate are not varied while taking the measurements to calculate the thermal efficiency, rate of change of stored energy in the water heater would be zero.

In response, DOE received several comments from interested parties and stakeholders. AHRI commented that no change is required to the test procedure to address this issue. According to AHRI, the intent of the test method is that the burner be operated at a continuous, full-input firing rate, and once steady state is achieved, there would not be any issue with regards to potential changes in stored heat within the water heater. (AHRI, No. 2 at p. 4) Rheem deferred to AHRI's comments of not requiring any change in the thermal efficiency test method. (Rheem, No. 3 at p. 2) Bradford White, HTP, and A.O.

Smith also commented on this issue. Bradford White did not see any merit in modifying the test procedure to account for variation in thermal energy stored in the tank. As a possible clarification, Bradford White suggested adding a sentence stating that, “flow rate must achieve continuous full rate burner operation at the required stable outlet water temperature.” According to Bradford White, stored energy would only be a significant consideration if the test conditions are not allowed to stabilize sufficiently or if the conditions are not controlled tightly. Bradford White recommended additional investigation of any modification that is proposed if DOE decides to amend the test procedure to account for stored energy changes. (Bradford White, No. 8 at pp. 1-2) A.O. Smith commented that the current test procedure for determining thermal efficiency has been used for a very long time without any confusion, and accordingly, A.O. Smith did not recommend any changes in the current test procedure. (A.O. Smith, No. 7 at p. 2) HTP commented that units are commonly pre-conditioned before the test, and recommended requiring products be pre-conditioned as part of the DOE test method. Further, HTP asserted that if tanks are pre-conditioned, it would not expect any additional accuracy achieved by accounting for the difference in energy maintained within the storage tank during the test. (HTP, No. 5 at p. 3) Joint Advocates encouraged any changes that would minimize systematic errors if the current test procedure is insufficiently specific and if an agreement can be reached on a reasonable method whose cost is commensurate to the value of the change. (Joint Advocates, No. 4 at p. 2)

DOE considered all comments received from interested parties in response to this issue. Based on the comments received, DOE has tentatively decided not to implement any changes in the current thermal efficiency test methods or calculations for CWH equipment to account for changes in thermal energy stored in the water heater during the course of the 30-minute test. However, DOE proposes to clarify the requirements for maintaining steady-state operation throughout the thermal efficiency test. Specifically, DOE proposes to clarify that no settings on the water heater may be changed during the course of the thermal efficiency test, once steady-state operation is achieved, as determined by no variation of outlet water temperature in excess of 2 °F over a 3-minute period. This includes setting the flow rate during testing such that the heater operates at full firing rate (

i.e.,

no modulation or cut-outs) for the entire duration of the test. Although the current test method is clear in requiring the test conditions to reach steady state prior to starting the test, there could be some confusion on whether these conditions are required to be maintained for the entire duration of the test. DOE proposes to add a statement to clarify steady-state operation during the thermal efficiency test. The proposed clarifying statement specifies that the test entity must maintain the outlet water temperature at 70 °F ± 2 °F above the supply water temperature and ensure the burner fires continuously at the full firing rate (

i.e.,

no modulation or cut-outs) for the entire duration of the thermal efficiency test. Further, the proposed statement clarifies that once steady-state operation is achieved, as determined by no variation of the outlet water temperature in excess of 2 °F over a 3-minute period, no settings on the water heating equipment may be changed until measurements for the thermal efficiency test are finished.

Additionally, DOE proposes to clarify a similar requirement for the standby loss test for CWH equipment other than those meeting DOE's proposed definition for “flow-activated instantaneous water heater.” DOE proposes to require that after the first cut-out before beginning the standby loss test, no settings may be changed on the water heating equipment until measurements for the standby loss test are finished.

Issue 8:

DOE requests comment on its proposed clarifying statements regarding steady-state operation and manipulation of CWH equipment settings during efficiency tests.

Definitions for Certain Consumer Water Heaters and Commercial Water Heating Equipment

1. Consumer Water Heaters

EPCA's definition of water heater specifies input ratings at or below which water heaters are to be classified as consumer water heaters (

e.g.,

75,000 Btu/h for gas-fired storage water heaters; 12 kW for electric storage water heaters and electric instantaneous water heaters; 210,000 Btu/h for oil-fired instantaneous water heaters). (42 U.S.C. 6291(27)) DOE's regulatory definition of “water heater” restates the definition from the consumer products part of EPCA. (42 U.S.C. 6291(27); 10 CFR 430.2) In addition to adopting EPCA's definition of water heater, DOE had defined a variety of terms that helped specify the test procedure provisions that applied to specific kinds of water heaters. See,

e.g.,

10 CFR part 430, subpart B, appendix E, in the 10 CFR parts 200 to 499 edition, revised as of January 1, 2015 (defining, for example, gas instantaneous water heater and electric storage-type water heater). These test procedure definitions included provisions related to water temperature design characteristics and rated storage volume. The standards at 10 CFR 430.32 and the water heater definition at 10 CFR 430.2 did not include any such limitations.

In the July 11, 2014 test procedure final rule, in an effort to consolidate all relevant definitions in 10 CFR 430.2, DOE removed the definitions for specific kinds of consumer water heaters from its test method at appendix E to subpart B of part 430 and added definitions to 10 CFR 430.2 (

i.e.,

“Electric heat pump water heater,” “Electric instantaneous water heater,” “Electric storage water heater,” “Gas-fired heat pump water heater,” “Gas-fired instantaneous water heater,” “Gas-fired storage water heater,” “Oil-fired instantaneous water heater,” and “Oil-fired storage water heater”). 79 FR 40542, 40549, 40566-67 (July 11, 2014). These definitions became effective on July 13, 2015, and excluded products with a rated storage capacity greater than 120 gallons and in some cases included limitations with respect to units designed to heat and store water at a thermostatically controlled temperature less than or equal to 180 °F. 79 FR 40542, 40566-67 (July 11, 2014). These changes to the definitions were proposed and finalized after the publication of the April 16, 2010 final rule setting amended standards for consumer water heaters, and they were not effective until after the April 16, 2015 compliance date for those standards. As noted previously, the standards and definition set forth in EPCA do not include any requirement related to the water temperature or storage capacity. Therefore, prior to the effectiveness of July 2014 regulation, any product meeting the definition of a “water heater” would have been subject to the statutory standards applicable to consumer water heaters, regardless of the water delivery temperature or storage capacity.

DOE now proposes to correct the definitions for specific types of consumer water heaters included at 10 CFR 430.2 by removing from the definitions the specifications related to the water temperature and storage capacity. Thus, a model that would otherwise meet the definition of a consumer water heater does not “become” commercial as the result of the unit's capability of producing water

at temperatures above 180 °F. More generally, a product that utilizes gas, oil, or electricity to heat potable water for use outside the heater upon demand that does not meet the statutory definition of “water heater” at 42 U.S.C. 6291(27) as implemented by this proposed rule, if adopted, would be a commercial water heater, subject to the standards for such water heaters as set forth in 42 U.S.C. 6313.

Furthermore, DOE notes that, if a manufacturer offers a product that meets the definition of a water heater at 10 CFR 430.2, but cannot be tested by the applicable test procedure, the manufacturer should notify DOE and request a waiver from the applicable test method using the procedures at 10 CFR 430.27. If a waiver were granted, DOE would update its test procedure in the next rulemaking for consumer water heaters. DOE does not anticipate, however, that such a waiver would be needed. The UEF test procedure was developed quite recently and was designed to span the consumer product/commercial equipment boundary; accordingly, DOE expects that all units (irrespective of designed water temperature and/or rated storage capacity) can be tested without difficulty.

In its definitions at 10 CFR 430.2, DOE currently defines the terms “electric heat pump water heater” and “gas-fired heat pump water heater.” In its energy conservation standards for consumer water heaters at 10 CFR 430.32(d), DOE does not use the terms “electric heat pump water heater” or “gas-fired heat pump water heater.” DOE's Uniform Test Method for Measuring the Energy Consumption of Water Heaters at appendix E to subpart B of part 430 also does not use these terms. Therefore, DOE proposes to remove these terms.

As discussed in the previous paragraphs, DOE proposes to revise the definitions for “Electric instantaneous water heater”, “Electric storage water heater”, “Gas-fired instantaneous water heater”, “Gas-fired storage water heater”, “Oil-fired instantaneous water heater”, “Oil-fired storage water heater”, in its regulations of consumer water heaters at 10 CFR 430.2 as set out in the regulatory text at the end of this document.

Issue 9:

DOE requests comment on its proposal to amend the definitions for consumer water heaters codified at 10 CFR 430.2 by removing the water temperature and storage capacity provisions. DOE also requests comment on its proposal to remove the definitions at 10 CFR 430.2 for “electric heat pump water heater” and “gas-fired heat pump water heater.”

2. Commercial Water Heating Equipment

DOE currently includes several definitions that include the terms “rated input” or “input rating” in its regulations for CWH equipment at 10 CFR 431.102. These definitions include “hot water supply boiler,” “instantaneous water heater,” “residential-duty commercial water heater,” and “storage water heater.” In section III.K of this NOPR, DOE proposes a new definition for “fuel input rate,” a value to be determined for all gas-fired and oil-fired CWH equipment. Therefore, DOE proposes to replace the terms “rated input” and “input rating” with the term “fuel input rate” for gas-fired and oil-fired CWH equipment in the definitions for CWH equipment at 10 CFR 431.102.

DOE's current definitions for “storage water heater” and “instantaneous water heater” in its regulations for CWH equipment codified at 10 CFR 431.102 do not include any criteria that exclude units that meet DOE's current definitions for consumer water heaters, as codified at 10 CFR 430.2. Therefore, DOE proposes to clarify these definitions for commercial water heaters by adding the input capacity criteria that distinguish between consumer and commercial water heaters for each energy source, as specified in EPCA's definition for consumer water heater. (42 U.S.C. 6291(27)) These proposed changes are consistent with DOE's proposed changes to its definitions for consumer water heaters, as discussed in section III.F.1.

DOE currently includes the definition for “instantaneous water heater” in its regulations for CWH equipment at 10 CFR 431.102. An instantaneous water heater is a water heater that has an input rating not less than 4,000 Btu/hr per gallon of stored water, and that is industrial equipment, including products meeting this description that are designed to heat water to temperatures of 180 °F or higher.

DOE believes that the last clause of the definition for “instantaneous water heater,” which includes units capable of heating water to temperature at or above 180 °F, does not serve a purpose in the definition. Without this clause, it would be assumed that units with this capability would be included in the definition because there is no restriction indicating otherwise. Therefore to simplify the definition, DOE proposes to remove this clause from the definition for “instantaneous water heater.” Additionally, with DOE's proposed addition of input criteria that distinguish between consumer and commercial water heaters previously discussed in this section, DOE believes that the clause “that is industrial equipment” does not serve to further clarify the scope of units covered by this definition. Therefore, DOE proposes to remove this clause from its definitions for “instantaneous water heater” and “storage water heater,” and revises the definitions as set out in the regulatory text at the end of this document.

In its regulations for CWH equipment at 10 CFR 431.102, DOE currently includes a definition for “packaged boiler” that is identical to that included for “commercial packaged boiler” at 10 CFR 431.82. DOE includes this definition for “packaged boiler” at 10 CFR 431.102 because the regulations for CWH equipment also include a definition for “hot water supply boiler,” and this definition specifies that a hot water supply boiler is a kind of packaged boiler. To simplify its regulations and reduce repetition, DOE proposes to remove the definition for “packaged boiler” from its regulations for CWH equipment at 10 CFR 431.102. Consequently, in its definition for “hot water supply boiler,” DOE proposes to replace the term “packaged boiler” with the term “packaged boiler (as defined in § 431.82).”

Issue 10:

DOE requests comment on its proposed changes to its definitions for CWH equipment: (1) Replacing the terms “rated input” and “input rating” with “fuel input rate” for gas-fired and oil-fired CWH equipment to match DOE's proposed definition for “fuel input rate;” (2) modifying DOE's definitions for “instantaneous water heater” and “storage water heater” by adding the input criteria that separate consumer water heaters and commercial water heaters and removing several phrases that do not serve to clarify coverage of units under the definitions; and (3) removing the definition of “packaged boiler.”

In section III.G, DOE discusses the reasons for a separate test procedure for water heaters and hot water supply boilers that require flow of water for heating water, and proposes a definition for “flow-activated water heater,” along with a test procedure for flow-activated water heaters as set out in the regulatory text at the end of this document.

In section III.J, DOE proposes a definition for “commercial heat pump water heater,” as well as a test procedure for commercial heat pump water heaters as set out in the regulatory text at the end of this document.

3. Residential-Duty Commercial Water Heaters

As required by AEMTCA, DOE established a uniform efficiency descriptor and accompanying test method for consumer water heaters and certain commercial water heaters in the July 2014 final rule. 79 FR 40542 (July 11, 2014). Specifically, AEMTCA required that the uniform efficiency descriptor and test method apply to all covered water heaters, including both consumer or commercial water heaters, except for certain commercial water heaters that do not have a residential use, can be clearly described, and are effectively rated using the thermal efficiency and standby loss descriptors. (42 U.S.C. 6295(e)(5)(F)) In the July 2014 final rule, DOE established input and volume criteria to distinguish commercial water heaters that do not have residential applications, based on comments from stakeholders. 79 FR 40542, 40586 (July 11, 2014). However, for four classes of residential-duty commercial water heaters—electric storage water heaters, heat pump water heaters, gas-fired instantaneous water heaters, and oil-fired instantaneous water heaters—the input criteria established to separate residential-duty commercial water heaters and commercial water heaters are identical to those codified at 10 CFR 430.2 that separate consumer water heaters and commercial water heaters. The criteria for these classes are shown in Table III-1. Because these input criteria are identical, by definition, no models can be classified under these four residential-duty equipment classes. Therefore, to eliminate potential confusion, DOE proposes to remove these classes from the definition for “residential-duty commercial water heater” codified at 10 CFR 431.102.

Table III-1—Indicator of Non-Residential Application for Certain Classes of CWH Equipment

Water heater class

Indicator of non-residential application

Electric storage

Rated input >12 kW; Rated storage volume >120 gallons.

Heat pump with storage

Rated input >12 kW; Rated current >24A at a rated voltage of not greater than 250 V; Rated storage volume >120 gallons.

Gas-fired instantaneous

Rated input >200 kBtu/h; Rated storage volume >2 gallons.

Oil-fired instantaneous

Rated input >210 kBtu/h; Rated storage volume >2 gallons.

DOE proposes to revise the definition for “residential-duty commercial water heater” as set out in the regulatory text at the end of this document.

Issue 11:

DOE requests comment on its proposal to modify the definition of “residential-duty commercial water heater” by removing from its scope the following classes: Electric storage water heaters, heat pump water heaters with storage, gas-fired instantaneous water heaters, and oil-fired instantaneous water heaters.

4. Storage-Type Instantaneous Water Heaters

The definitions for “instantaneous water heater” and “hot water supply boiler” set forth in 10 CFR 431.102 include CWH equipment with an input rating of at least 4,000 Btu/h per gallon of stored water. These definitions, therefore, include both instantaneous water heaters and hot water supply boilers without integral storage tanks, as well as instantaneous water heaters with integral storage tanks (but with at least 4,000 Btu/h of input per gallon of stored water). DOE believes these two groups of equipment—water heaters with and without integral storage tanks—are fundamentally different in their construction and application and have different energy losses that need to be accounted for during efficiency testing. DOE has tentatively concluded that instantaneous water heaters with an integral storage tank (“storage-type instantaneous water heaters”) should be tested in a manner similar to commercial storage water heaters. Therefore, DOE proposes to adopt a test method specifically applicable to “storage-type instantaneous water heaters” that is the same as the test method for commercial storage water heaters. DOE proposes to define “storage-type instantaneous water heater” as set out in the regulatory text at the end of this document.

Issue 12:

DOE seeks comment on its proposed definition of “storage-type instantaneous water heater.”

It is DOE's understanding that storage-type instantaneous water heaters are very similar to storage water heaters, but with a higher ratio of input rating to tank volume. This higher input-volume ratio is achieved with a relatively larger heat exchanger paired with a relatively smaller storage tank. However, through a review of product literature, DOE noted no significant design differences between models in these two proposed equipment classes that warrant separate test procedures for thermal efficiency or standby loss. Therefore, DOE proposes that the proposed test procedures for storage water heaters apply also to storage-type instantaneous water heaters.

G. Standby Loss Test for Flow-Activated Instantaneous Water Heaters

The current Federal standby loss test method for CWH equipment incorporates by reference ANSI Z21.10.3-2011, including Exhibit G.2 which assumes that the water heater would automatically initiate the next firing cycle when the internal water temperature (measured using the internal tank thermostat) falls below its allowable minimum value. An underlying assumption for the standby loss test is that the ignition of the burner or activation of the electric element is solely dependent on the feedback control signal from the internal tank thermostat. This assumption, although true for most CWH equipment, is not applicable to certain instantaneous water heaters and hot water supply boilers that require continuous water flow through the heat exchanger in order to activate the next firing cycle.

Measuring standby loss for such flow-activated instantaneous water heaters with a storage volume greater than or equal to 10 gallons was raised as an issue by AHRI. (AHRI, No. 2 at pp. 4-5) Specifically, AHRI commented that the current standby loss test is designed for tank-type water heaters and does not address water heaters that can fire only when hot water is being drawn. (AHRI, No. 2 at pp. 4-5) On August 25, 2014, AHRI provided a supplemental comment with a recommended standby loss test method for tube-type instantaneous water heaters having a capacity of 10 gallons or more (“2014 AHRI-recommended test method”), which includes a suggested test method for models that are flow-activated. AHRI also mentioned in its comments that their recommended test method is being considered as an addition to the ANSI Z21.10.3 standard, and was at that time under review by the ANSI Z21/83 committee. (AHRI, No. 10 at p. 1)

DOE considered the comments received from AHRI and reviewed its

recommended standby loss test method for tube-type instantaneous water heaters having a capacity of 10 gallons or more. Based on its review, DOE agrees with AHRI's argument that the current standby loss test method as set forth in Exhibit G.2 of ANSI Z21.10.3-2011 (incorporated by reference in the DOE test procedures) is designed for thermostatically-controlled, tank-type (or storage) water heaters and acknowledges concerns about the applicability to flow-activated water heaters. The current test procedure does not provide any indication of how to test flow-activated instantaneous water heaters that have no means of firing or heating if there is no flow of water through the system. Therefore, DOE has tentatively concluded that a different standby loss test procedure is required for flow-activated instantaneous water heaters. To differentiate units for which the proposed standby loss test procedure discussed in this section will apply, DOE proposes to define “flow-activated instantaneous water heater” as set out in the regulatory text at the end of this document.

Issue 13:

DOE requests comment on its proposed definition for “flow-activated instantaneous water heater.” Specifically, DOE requests feedback on whether the definition includes all units and designs for which a separate standby loss test procedure is warranted, and whether any units would be included that do not need a test method separate from the current standby loss test procedure for CWH equipment.

DOE notes that the requirement to measure a “mean tank temperature” to calculate the standby loss would also be an issue for all instantaneous water heaters and hot water supply boilers that have a storage capacity of 10 gallons or more and that do not meet DOE's proposed definition of “storage-type instantaneous water heater”, because these units do not have an integral tank, and the heat exchanger geometry can make obtaining an accurate reading of the water stored within the heat exchanger difficult to obtain. DOE has addressed this issue both in its proposed test method for flow-activated instantaneous water heaters contained within this section, and in proposed changes to the current standby loss test procedure for other instantaneous water heaters and hot water supply boilers discussed in section III.I of this NOPR.

To develop a new Federal standby loss test procedure for flow-activated instantaneous water heaters, DOE first reviewed the 2014 AHRI-recommended test method. After its review, DOE identified potential issues and provided AHRI with questions seeking further clarifications on various aspects of their recommended test method related to conduct of the test, duration of test, flow and temperature measurements, and the equations used to calculate standby loss. On August 17, August 18, and December 14, 2015, DOE received separate responses from AHRI members Thermal Solutions Inc., Raypak Inc. and A. O. Smith, respectively.

The responses provide answers to all the questions posed by DOE and clarified the intent of the 2014 AHRI-recommended test method.

The response from Thermal Solutions Inc. can be found in the docket for this rulemaking at:

http://www.regulations.gov/#!documentDetail;D=EERE-2014-BT-TP-0008-0011

The response from Raypak Inc. can be found at:

http://www.regulations.gov/#!documentDetail;D=EERE-2014-BT-TP-0008-0012

The responses from A.O. Smith can be found at:

http://www.regulations.gov/#!documentDetail;D=EERE-2014-BT-TP-0008-0014

In November 2015, ANSI published an updated version of the ANSI Z21.10.3 test standard. This updated version, ANSI Z21.10.3-2015, includes Annex E.3, which describes a test method for measuring the standby loss of tube-type instantaneous water heaters having a storage capacity of 10 gallons or more. DOE reviewed this section carefully and found it to be similar to the Annex E.3 included in the 2014 AHRI-recommended test method. The only difference DOE identified between the two versions of Annex E.3 was the referenced section for determining the volume of water contained in the water heater. Specifically, Annex E.3 in the 2014 AHRI-recommended test method references to section 5.27 of ANSI Z21.10.3 for determining the water contained in the water heater, while Annex E.3 of ANSI Z21.10.3-2015 references section 5.28 of ANSI Z21.10.3-2015, “Capacities of tube type water heaters.” After carefully comparing the 2014 AHRI-recommended test method with Annex E.3 of ANSI Z21.10.3-2015, DOE believes that ANSI Z21.10.3-2015 renumbered section 5.27 as 5.28, and that AHRI's reference to section 5.27 was referring to the section titled “Capacities of tube type water heaters.” Therefore, DOE has tentatively concluded that there are no substantive differences between the 2014 AHRI-recommended test method and the test method contained in Annex E.3 of ANSI Z21.10.3-2015.

As previously discussed, prior to the publication of ANSI Z21.10.3-2015, DOE posed several questions and sought clarifications from AHRI on various aspects of the 2014 AHRI-recommended test method. Thermal Solutions Inc., Raypak Inc., and A.O. Smith provided responses to DOE's questions. The major issues on which DOE sought clarification, along with the manufacturer responses, are described in the following paragraphs.

First, DOE sought clarification as to whether the 2014 AHRI-recommended test method applies to all tube-type (thermostatically-activated and flow-activated) water heaters with a storage capacity of 10 gallons or more, or only to flow-activated instantaneous water heaters. DOE notes that AHRI's comments indicate that the test procedure is exclusively for flow-activated instantaneous water heaters. However, the title of the 2014 AHRI-recommended test method indicates that the test applies to all “tube-type” instantaneous water heaters. (AHRI, No. 10 at p.4) Judging by the title and the language used in the test method, DOE initially interpreted the test method as divided into two distinct parts: (1) The first part pertaining to tube-type instantaneous water heaters that are thermostatically-activated and are not flow-activated;

and (2) the second part pertaining to water heaters that will neither initiate, nor cause actions that will initiate, burner operation based on a thermostatic control. DOE interpreted this second part of the test procedure to be applicable to flow-activated instantaneous water heaters that are not thermostatically-activated. However, the responses from Raypak and Thermal Solutions indicate that the entire 2014 AHRI-recommended test method (Annex E.3) is exclusively meant for flow-activated instantaneous water heaters. Raypak and Thermal Solutions stated that the first part of the test method is meant for water heaters that are flow-activated but may have some other form of energy-consuming function or water circulation during the conduct of the standby loss test. (Thermal Solutions, No. 11 at p 1; Raypak, No. 12 at p. 2) A.O. Smith also stated that DOE's interpretation was incorrect, and that the 2014 AHRI-recommended test method is divided into two parts to cover different designs of instantaneous water heaters whose tube type heat exchangers happen to

store ten gallons or more. A.O. Smith further stated that the first part of the test method addresses instantaneous water heaters whose burners may activate by some specialty feature (

e.g.,

frost control) and the second part of the test method addresses more common designs that are installed with a remote storage tank and a thermostat that activates the water pump, which then activates the burners. A.O. Smith also stated that the first part of the 2014 AHRI-recommended test method does not address thermostatically-activated models. (A.O. Smith No. 14 at p. 1)

The first equation for standby loss calculated in the first part of 2014 AHRI-recommended test method includes a term for fuel consumed. The test procedure also states that the second equation is for units for which the main burner(s) do not cycle back on during the course of the test. Based on this language, DOE interpreted the first part (that includes the first and second equation) to be for units that are thermostatically-activated and not flow-activated.

Thermal Solutions and Raypak did not comment on DOE's interpretation of the second part of the 2014 AHRI-recommended test method. However, judging by the response from A.O. Smith regarding the second part and the responses from A.O. Smith, Thermal Solutions, and Raypak regarding the first part, DOE infers that the second part of the test procedure is meant for flow-activated instantaneous water heaters that do not have any form of energy consumption or water circulation during the conduct of the standby loss test. (Thermal Solutions, No. 11 at p 1; Raypak, No. 12 at p. 2; A.O. Smith No. 14 at p. 1)

DOE also sought clarifications on the equations used to calculate the standby loss in both parts of the 2014 AHRI-recommended test method. In the first equation of the 2014 AHRI-recommended test method, DOE noticed an inconsistency in units of measurement. (AHRI, No. 10 at p. 5) When calculated, the first term of this equation has the units Btu/h, while the second term has the units 1/h. Mathematically, a subtraction or addition operation cannot be applied over two numbers that have different units of measurement. In their responses, the manufacturers also acknowledged the issues with regards to the equations for calculating standby loss and stated that AHRI has worked on a corrected derivation for the equations of this test procedure. (Thermal Solutions, No. 11 at p 3; Raypak, No. 12 at p. 4; A.O. Smith No. 14 at p. 3) DOE notes that later versions of the AHRI-recommended test methods (discussed later in this section) rectify this error in the first equation of the 2014 AHRI-recommended test method. However, the later versions of the AHRI-recommended test methods convert standby loss units from percent-per-hour of the heat content of the stored water to Btu-per-hour based on a temperature difference of the average value of the outlet water temperature minus the average value of the ambient temperature measured during the course of the test. This method of calculation does not match with the standby loss definition that is currently set forth in 10 CFR 431.102, which is based on a temperature difference of 70 °F between the stored water and the ambient air. Therefore, DOE has tentatively decided not to consider this equation for the proposed standby loss test procedure for flow-activated instantaneous water heaters.

In the second equation of the 2014 AHRI-recommended test method, DOE sought to understand the rationale for choosing a temperature difference term that is equal to the difference between the outlet water temperature and supply water temperature to calculate the thermal energy lost during the test. (AHRI, No. 10 at p. 5) In the third equation of the 2014 AHRI-recommended test method, DOE sought to understand the rationale for assuming a constant temperature difference of 70 °F between the supply water and the outlet water temperature. Further, the third equation appeared to assume that the outlet water in the water heater will cool down to the supply water temperature over a span of exactly 24 hours during the conduct of the test. (AHRI, No. 10 at p. 6) On the issue of considering the temperature difference between the outlet water temperature and supply water temperature to calculate the loss in thermal energy during the test, the manufacturers stated that AHRI has conservatively assumed the temperature of stored water inside the water heater to be equal to the outlet water temperature. The manufacturers stated that the geometry of these water heaters does not allow for the measurement of the mean stored water temperature inside the water heater. As a consequence, the commenters suggested using the outlet water temperature in place of the mean stored water temperature to carry out the standby loss calculations. (Thermal Solutions, No. 11 at pp. 3, 5; Raypak, No. 12 at pp. 4, 6; A.O. Smith No. 14 at pp. 3-5). The manufacturers also stated that they are willing to accept a conservative estimate of the standby loss in order to reduce the complexity and burden of the test method. (Thermal Solutions, No. 11 at p. 3; Raypak, No. 12 at p. 4; A.O. Smith No. 14 at p. 3-5)

DOE also sought clarification on the duration of the standby loss test. In particular, DOE sought an answer to whether any consideration was given to the possibility that flow-activated water heater burners may not cycle on at any point during the test and instead cool down completely in less than 24 hours. The manufacturers' responses to this question indicated that the suggested test method includes a one-hour test, and it is assumed that all the heat is lost in the heat exchanger. (Thermal Solutions, No. 11 at p 4; Raypak, No. 12 at p. 4; A.O. Smith No. 14 at p. 5)

Another issue that DOE sought clarification on is the method used to measure the storage volume of the water heater. Section 5.27 of ANSI Z21.10.3-2015 (that is the same as section 5.26 of ANSI Z21.10.3-2011, 2013, and 2014), “Capacities of storage vessels,” describes a method of test to measure the storage volume of a water heater containing a storage vessel or with an input rating less than 4,000 Btu/h per gallon of water stored. The 2014 AHRI-recommended test method specifies using the methodology described in section 5.27 of ANSI Z21.10.3, that DOE believes corresponds to section 5.28 of ANSI Z21.10.3-2015, “Capacities of tube type water heaters.” DOE reviewed section 5.28 of ANSI Z21.10.3-2015 carefully, and noticed that this section does not specify a method for determining the volume of tube-type water heaters; instead, it only states that the volume shall be determined. DOE sought clarifications on the rationale for using the test method described in section 5.28, “Capacities of tube type water heaters” of ANSI Z21.10.3-2015 as opposed to section 5.27, “Capacities of storage vessels” of ANSI Z21.10.3-2015 (that is the same as section 5.26 of ANSI Z21.10.3-2011, 2013 and 2014). Section 5.26 of ANSI Z21.10.3-2011 is used for measuring the storage volume of all CWH equipment in Exhibit G.2 of ANSI Z21.10.3-2011, which is incorporated by reference in the current Federal standby loss test procedure.

In response to this issue, the manufacturers stated that determining the stored volume using section 5.26 of ANSI Z21.10.3 (which DOE interprets as referring to section 5.26 of ANSI Z21.10.3-2011, 2013, and 2014, “Capacities of storage vessels,” which corresponds to section 5.27 of ANSI Z21.10.3-2015) is only required for water heaters that are known to have a stored water capacity greater than or equal to ten gallons and that the test is not required for water heaters with less than ten gallons of storage capacity. The manufacturers' comments indicate that they believe the test method to measure the storage volume is left to the discretion of the certification body. The manufacturers further stated that the test method in section 5.26 may not be a reliable test method for water heaters with small water volumes, manifold coils, and complex geometries. Moreover, they stated that heat exchangers used in the water heaters are

hydrostatically tested before the assembly, as required by the American Society of Mechanical Engineers (ASME) and will always have some residual water in the heat exchanger. According to the manufacturers, this residual water will result in inaccurate measurement of the volumetric capacity of the water heater. (Thermal Solutions, No. 11 at pp. 1-2; Raypak, No. 12 at p. 2; A.O. Smith No. 14 at pp. 1-2)

Another issue that DOE noticed with the test procedure in Annex E.3 of ANSI Z21.10.3-2015 is that (similar to the 2014 AHRI-recommended test method) the first part of Annex E.3 of ANSI Z21.10.3-2015 appears to be for thermostatically-activated units. Annex E.3 of ANSI Z21.10.3-2015 does not appear to be applicable exclusively to flow-activated instantaneous water heaters as is indicated by the manufacturers in their responses and AHRI in the 2014 AHRI-recommended test method. (AHRI, No. 10 at p. 4; Thermal Solutions, No. 11 at pp. 1; Raypak, No. 12 at pp. 1-2; A.O. Smith, No. 14 at p. 1)

On December 2, 2015, AHRI submitted another supplemental comment to the February 2014 RFI that included a revised recommendation for a test method for measuring standby loss for tube-type commercial instantaneous water heaters and hot water supply boilers that contain more than 10 gallons of water (“2015 AHRI-recommended test method”). (AHRI (2015), No. 13, pp.1, 6-8)

DOE compared the 2014 AHRI-recommended test method with the 2015 AHRI-recommended test method to identify the differences between the two test methods. In the 2015 AHRI-recommended test method, AHRI updated the equations for calculation of standby loss in its recommended Annex E.3. After reviewing these revised equations, DOE notes that the first equation in Annex E.3 of the 2015 AHRI-recommended test method is the result of converting the current equation for standby loss specified in Exhibit G.2 of ANSI Z21.10.3-2011 (but with the mean tank temperature replaced with the outlet water temperature) from units denominated as percentage-per-hour to units denominated as Btu-per-hour, by multiplying by a term consisting of

× V

× Δ

/100.

DOE also notes that the second equation provided in the 2015 AHRI-recommended test method is identical to the second equation that is provided in the 2014 AHRI-recommended test method and as stated in the test method, is used for water heaters for which the main burner(s) do not cycle on during the course of the test. The final equation in the 2015 AHRI-recommended test method specifies the time for the duration of the test as 24 hours, similar to the 2014 AHRI-recommended test method. However, in the 2015 AHRI-recommended test method, the variables used in the final equation and the variables defined after the equation are not consistent—specifically, the equation contains the term Δ

, while the list of variables below the equation includes Δ

. The final equation in the 2015 AHRI-recommended test method uses Δ

, while the final equation in the 2014 AHRI-recommended test method uses Δ

. Other than the differences mentioned in this paragraph, DOE tentatively determined that the 2015 AHRI-recommended test method contains no additional substantive differences from the previously submitted 2014 AHRI-recommended test method. Therefore, other than these differences, all issues that DOE identified with the standby loss test in the 2014 AHRI-recommended test method also apply to the 2015 AHRI-recommended test method.

DOE received two supplemental comments from AHRI in response to the February 2014 RFI on December 2, 2015 and January 11, 2016. Both comments are included in the docket under filing number EERE-2014-BT-TP-0008-0013. To differentiate between the two documents for citations, DOE uses “AHRI (2015)” and “AHRI (2016)” to refer to the comment received on December 2, 2015 and on January 11, 2016, respectively. Both supplemental comments can be found at:

http://www.regulations.gov/#!documentDetail;D=EERE-2014-BT-TP-0008-0013

Annex E.2 of ANSI Z21.10.3-2013 (and 2014) defines `K' as the nominal specific heat of water that has a value of 8.25 Btu per gallon. This is the same as `k' that is used by AHRI in their equations in the Annex E.3 of the 2015 and 2016 AHRI-recommended test method. The term Va refers to the measured volume expressed in gallons and measured as per section 5.27 of ANSI Z21.10.3-2015 and Δ

refers to the difference between the average value of the outlet water temperature and the average value of the ambient temperature expressed in °F.

On January 11, 2016, AHRI submitted a third supplemental comment to the February 2014 RFI that included a further revised recommendation for a test method for measuring standby loss for tube-type commercial instantaneous water heaters and hot water supply boilers that contain more than 10 gallons of water (“2016 AHRI-recommended test method”). (AHRI (2016), No. 13, pp.1, 6-8) After carefully reviewing this submission, DOE tentatively determined that the only difference between the 2015 AHRI-recommended test method and the 2016 AHRI-recommended test method are the temperature differences used in equations for calculating standby loss. Specifically, the temperature difference used in the first two equations in Annex E.3 of the 2016 AHRI-recommended test method is Δ

, which represents the difference between the final outlet water temperature and the initial outlet water temperature. This differs from the temperature difference terms used in the corresponding standby loss equations in the 2015 AHRI-recommended test method, which are denoted as Δ

and defined as the difference between the average supply water temperature and the outlet temperature. In the final standby loss equation in Annex E.3, the temperature difference used is Δ

, which represents 70 °F, the difference between the supply and outlet water temperatures, and was previously denoted as Δ

in the corresponding equation in the 2015 AHRI-recommended test method. These changes in temperature difference terms in standby loss equations help to clarify issues with these terms that DOE identified in the 2015 AHRI-recommended test method. However, with the exception of these temperature difference terms, the other issues that DOE identified with the 2014 and 2015 AHRI-recommended test methods also apply to the 2016 AHRI-recommended test method.

DOE has considered the initially submitted 2014 AHRI-recommended test method, the clarifications provided by manufacturers, Annex E.3 of the recently published ANSI Z21.10.3-2015, and the recently submitted 2015 and 2016 AHRI-recommended test methods in developing the proposed standby loss test procedure for flow-activated instantaneous water heaters. DOE agrees with certain aspects of the recommended test methods and the related clarifications; however, DOE tentatively concludes that there are several modifications that need to be made to the 2016 AHRI-recommended test method for it to be used as a Federal standby loss test procedure for flow-activated instantaneous water heaters. As noted previously, the only difference between the 2016 AHRI-recommended test method and Annex E.3 of ANSI Z21.10.3-2015 is with regards to the first equation in both test methods and, similarly, DOE is not proposing to adopt the test method in Annex E.3 as the Federal test method. Rather, the following paragraphs describe DOE's proposed test method, including differences from both the 2016 AHRI-recommendation and the ANSI Z21.10.3-2015 test method, and the reasons such changes are deemed necessary.

As previously defined in this section, a flow-activated instantaneous water heater will initiate firing or heating only

when water is being drawn from the water heater. In Annex E.3 of ANSI Z21.10.3-2015 and the 2016 AHRI-recommended test method, the water heater is kept in standby mode, and no hot water is drawn from the equipment during the standby loss test. Under such conditions, the water heater would not be expected to initiate burner or heating element operation at any point during the course of the test since there is no flow to activate the heat source. As a result, hot water stored in the water heater in standby mode will continuously lose heat to the environment until the water temperature approaches the surrounding ambient air temperature. DOE considers this standby mode operation for flow-activated instantaneous water heaters to be characteristically different from the standby mode operation of thermostatically-activated water heaters, where the main burner or element(s) cycles on when the water temperature drops below the thermostat set point.

The first part of Annex E.3 of ANSI Z21.10.3-2015 and the 2016 AHRI-recommended test method appears to apply to water heaters that may circulate water or initiate some other energy-consuming function when hot water is not being drawn. If a water heater consumes energy for the purpose of heating water during the standby mode, then such a water heater would not fit the proposed definition of a “flow-activated instantaneous water heater.” Such water heaters would instead be covered by the proposed standby loss test method for instantaneous water heaters and hot water supply boilers that are not flow-activated, as discussed in section III.I of this NOPR. However, to account for other types of fuel consumption during standby mode (

i.e.,

other than directly for the purpose of heating water), DOE has retained the fuel consumption terms in the proposed standby loss equation for flow-activated instantaneous water heaters.

The driving temperature difference that causes the constant heat loss to the ambient air from the water heater is the difference between the stored water and the ambient air temperature. This temperature difference must be factored into the standby loss calculations, as included in the 2016 AHRI-recommended test method, instead of the temperature difference between outlet and supply water that is used in Annex E.3 of ANSI Z21.10.3-2015 and the 2015 AHRI-recommended test method. In addition, the current standby loss test procedure that is set forth in Exhibit G.2 of ANSI Z21.10.3-2011 (incorporated by reference into the current DOE test procedure) calculates the standby loss as a percentage per hour of the total heat content of the water heater. In DOE's test procedure for gas-fired and oil-fired CWH equipment as set forth in 10 CFR 431.106, DOE uses this percent-per-hour standby loss value to calculate the standby loss in terms of Btu/h based on the storage volume and a 70 °F temperature difference between the stored water and the ambient air temperature. DOE notes that the 2016 AHRI-recommended test method converts from standby loss in terms of percent-per-hour to standby loss in terms of Btu-per-hour by multiplying by a term that includes Δ

, which is defined in Annex E.3 of ANSI Z21.10.3-2015 as the difference between the outlet water temperature and the average value of the ambient temperature. This is in contrast to: (1) DOE's current test procedure as specified in 10 CFR 431.106, which converts using a fixed 70 °F temperature difference rather than using the measured temperature difference from testing and, (2) the current definition of “standby loss” specified in 10 CFR 431.102 that defines “standby loss” as the average energy required to maintain the stored water temperature, expressed in Btu per hour based on a 70 °F temperature differential between stored water and ambient temperature.

DOE notes that use of a fixed 70 °F temperature difference allows for straightforward conversion of standby loss from one set of units to another, while use of the measured temperature difference requires the availability of data from efficiency testing. DOE sees value in such a straightforward conversion, so that those without access to efficiency test data can still convert between the two values. Additionally, the standby loss test method that is proposed for flow-activated instantaneous water heaters already takes into account the measured temperature difference between the outlet water temperature and the ambient air temperature, making the additional inclusion of this term in the conversion unnecessary. Finally, use of a constant 70 °F temperature difference would make the conversion in this proposed standby loss test procedure consistent with that in DOE's current test procedure at 10 CFR 431.106, and DOE also proposes this method of conversion to standby loss in terms of Btu/h for other classes of gas-fired and oil-fired CWH equipment in appendices A and C to subpart G of 10 CFR part 431. Therefore, DOE proposes to use the same approach of a constant 70 °F temperature difference to calculate the standby loss for gas-fired and oil-fired flow-activated instantaneous water heaters. For electric flow-activated instantaneous water heaters, DOE proposes to maintain a standby loss metric in terms of a percent-per-hour value

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