Energy Conservation Program: Test Procedure for Consumer Water Heaters and Residential-Duty Commercial Water Heaters

Federal RegisterJun 21, 2023

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DEPARTMENT OF ENERGY

10 CFR Parts 429, 430, and 431

[EERE-2019-BT-TP-0032]

RIN 1904-AE77

Energy Conservation Program: Test Procedure for Consumer Water Heaters and Residential-Duty Commercial Water Heaters

AGENCY:

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

ACTION:

Final rule.

SUMMARY:

This final rule incorporates by reference the latest version of the industry testing standard for consumer water heaters and residential-duty commercial water heaters and adopts relevant portions of those standards into the Federal test procedure. In this final rule, the U.S. Department of Energy (DOE) is also expanding the scope of coverage of the test procedure to apply to certain consumer water heater designs (including circulating water heaters and low-temperature water heaters), adding definitions for certain specialty water heaters, updating test conditions and tolerance requirements to reduce burden, clarifying test set-up and installation methods, addressing the test conduct for products which can store water at temperatures above the delivery setpoint, establishing an effective volume calculation, and extending untested provisions to electric instantaneous water heaters.

DATES:

The effective date of this rule is July 21, 2023. The final rule changes will be mandatory for consumer water heater testing starting December 18, 2023 and for residential-duty commercial water heater testing starting June 17, 2024. The incorporation by reference of certain material listed in this rule is approved by the Director of the Federal Register on July 21, 2023.

ADDRESSES:

The docket, which includes

Federal Register

notices, public meeting attendee lists and transcripts, comments, and other supporting documents/materials, is available for review at

www.regulations.gov.

All documents in the docket are listed in the

www.regulations.gov

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

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

www.regulations.gov/docket/EERE-2019-BT-TP-0032.

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

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

ApplianceStandardsQuestions@ee.doe.gov.

FOR FURTHER INFORMATION CONTACT:

Ms. Julia Hegarty, U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Office, EE-5B, 1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: (202) 597-6737. Email:

ApplianceStandardsQuestions@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) 586-5827. Email:

Eric.Stas@hq.doe.gov.

SUPPLEMENTARY INFORMATION:

DOE incorporates by reference the following industry standards into part 430:

ANSI/ASHRAE Standard 41.1-2020, “Standard Methods for Temperature Measurement,” ANSI-approved June 30, 2020 (“ASHRAE 41.1-2020”).

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

ANSI/ASHRAE Standard 118.2-2022, “Method of Testing for Rating Residential Water Heaters and Residential-Duty Commercial Water Heaters,” ANSI-approved March 1, 2022 (“ASHRAE 118.2-2022”).

Copies of ASHRAE 41.1-2020, ASHRAE 41.6-2014, and ASHRAE 118.2-2022 can be obtained from the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc., (ASHRAE), 180 Technology Parkway NW, Peachtree Corners, GA 30092, (800) 527-4723 or (404) 636-8400, or online at:

www.ashrae.org.

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

ASTM E97-82 (Reapproved 1987) “Standard Test Methods for Directional Reflectance Factor, 45-Deg 0-Deg, of Opaque Specimens by Broad-Band Filter Reflectometry,” approved October 29, 1982 and withdrawn 1991 (“ASTM E97-1987 (W1991)”).

Copies of ASTM D2156-09 (RA 2018) can be obtained from ASTM International (ASTM), 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959 or online at:

www.astm.org.

Copies of ASTM E97-1987 (W1991) are reasonably available from standards resellers including GlobalSpec's Engineering 360 (

https://standards.globalspec.com/std/3801495/astm-e97-82-1987

) and IHS Markit (

https://.global.ihs.com/doc_detail.cfm?document_name=ASTM%20E97&item_s_key=00020483

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

Table of Contents

I. Authority and Background

A. Authority

B. Background

II. Synopsis of the Final Rule

III. Discussion

A. Scope of Applicability and Definitions

1. Demand-Response Water Heaters

2. Heat Pump Water Heaters

3. Residential-Duty Commercial Water Heaters

4. Specialty Water Heaters

B. Updates to Industry Standards

1. ASHRAE 41.1-2020

2. ASHRAE 118.2-2022

C. Test Conditions and Tolerances

1. Supply Water Temperature Measurements

2. Gas Pressure

3. Input Rate

4. Ambient Test Condition Tolerances

5. Electrical Supply Voltage Tolerances

6. Flow Rate Tolerances

7. Optional Test Conditions for Heat Pump Water Heaters

D. Test Set-Up and Installation

1. Split-System Heat Pump Water Heaters

2. Mixing Valves

3. Flow Meter Location

4. Separate Storage Tanks

E. Test Conduct

1. High Temperature Testing

2. Very Small Draw Pattern Flow Rate

3. Low-Temperature Water Heaters

4. Delivery Temperature for Flow-Activated Water Heaters

5. Heat Pump Water Heaters

6. Draw Pattern for Commercial Applications

7. Method for Determining Internal Tank Temperature for Certain Water Heaters

8. Alternate Order 24-Hour Simulated-Use Test

F. Computations

1. Mass Calculations

2. Effective Storage Volume

G. Untested Provisions (Alternative Efficiency Determination Methods)

1. Representations of First-Hour Ratings for Untested Basic Models

2. Alternative Rating Method for Electric Instantaneous Water Heaters

H. Corrections and Clarifications

1. Flow-Activated Terminology

2. Second Identical 24-Hour Simulated-Use Test

3. Connected Products

4. Heating Value of Gas

I. Effective and Compliance Dates

J. Test Procedure Costs

1. Separate Storage Tanks

2. Method for Determining Internal Tank Temperature for Certain Water Heaters

3. High Temperature Testing

4. Additional Amendments

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Orders 12866, 13563, and 14094

B. Review Under the Regulatory Flexibility Act

C. Review Under the Paperwork Reduction Act of 1995

D. Review Under the National Environmental Policy Act of 1969

E. Review Under Executive Order 13132

F. Review Under Executive Order 12988

G. Review Under the Unfunded Mandates Reform Act of 1995

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

I. Review Under Executive Order 12630

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

K. Review Under Executive Order 13211

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

M. Congressional Notification

N. Description of Materials Incorporated by Reference

V. Approval of the Office of the Secretary

I. Authority and Background

Consumer water heaters are included in the list of “covered products” for which DOE is authorized to establish and amend energy conservation standards and test procedures. (42 U.S.C. 6292(a)(4)) DOE's energy conservation standards and test procedures for consumer water heaters are currently prescribed respectively at title 10 of the Code of Federal Regulations (CFR), part 430, section 32(d), and 10 CFR part 430, subpart B, appendix E ((appendix E),

Uniform Test Method for Measuring the Energy Consumption of Water Heaters.

Residential-duty commercial water heaters, for which DOE is also authorized to establish and amend energy conservation standards and test procedures (42 U.S.C. 6311(1)(K)), must also be tested according to appendix E. 10 CFR 431.106(b)(1) (

See

42 U.S.C. 6295(e)(5)(H)). DOE's energy conservation standards for residential-duty commercial water heaters are currently prescribed at 10 CFR 431.110(b)(1). The following sections discuss DOE's authority to establish and amend test procedures for consumer water heaters and residential-duty commercial water heaters, as well as relevant background information regarding DOE's consideration of test procedures for these products and equipment.

A. Authority

The Energy Policy and Conservation Act, as amended (EPCA),

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

of EPCA established the Energy Conservation Program for Consumer Products Other Than Automobiles, which sets forth a variety of provisions designed to improve energy efficiency. (42 U.S.C. 6291-6309, as codified) These products include consumer water heaters, one of the subjects of this document. (42 U.S.C. 6292(a)(4)) Title III, Part C

of EPCA, added by Public Law 95-619, Title IV, section 441(a), established the Energy Conservation Program for Certain Industrial Equipment, which again sets forth a variety of provisions designed to improve energy efficiency. (42 U.S.C. 6311-6317, as codified) This equipment includes residential-duty commercial water heaters, which are also the subject of this document. (42 U.S.C. 6311(1)(K))

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

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

For editorial reasons, upon codification in the U.S. Code, Part C was redesignated Part A-1.

The energy conservation program under EPCA consists essentially of four parts: (1) testing, (2) labeling, (3) Federal energy conservation standards, and (4) certification and enforcement procedures. Relevant provisions of EPCA specifically include definitions (42 U.S.C. 6291; 42 U.S.C. 6311), test procedures (42 U.S.C. 6293; 42 U.S.C. 6314), labeling provisions (42 U.S.C. 6294; 42 U.S.C. 6315), energy conservation standards (42 U.S.C. 6295; 42 U.S.C. 6313), and the authority to require information and reports from manufacturers (42 U.S.C. 6296; 42 U.S.C. 6316).

The Federal testing requirements consist of test procedures that manufacturers of covered products and commercial equipment must use as the basis for: (1) certifying to DOE that their products/equipment comply with the applicable energy conservation standards adopted pursuant to EPCA (42 U.S.C. 6295(s); 42 U.S.C. 6296; 42 U.S.C. 6316(a)-(b)), and (2) making other representations about the efficiency of those products/equipment (42 U.S.C. 6293(c); 42 U.S.C. 6314(d)). Similarly, DOE must use these test procedures to determine whether the products comply with any relevant standards promulgated under EPCA. (42 U.S.C. 6295(s))

Federal energy efficiency requirements for covered products and equipment established under EPCA generally supersede State laws and regulations concerning energy conservation testing, labeling, and standards. (42 U.S.C. 6297(a)-(c); 42 U.S.C. 6316(a)-(b)) DOE may, however, grant waivers of Federal preemption in limited circumstances for particular State laws or regulations, in accordance with the procedures and other provisions of EPCA. (42 U.S.C. 6297(d); 42 U.S.C. 6316(a); 42 U.S.C. 6316(b)(2)(D))

Under 42 U.S.C. 6293, EPCA sets forth the criteria and procedures DOE must follow when prescribing or amending test procedures for covered products. Specifically, EPCA requires that any test procedures prescribed or amended shall be reasonably designed to produce test results which measure energy efficiency, energy use, or estimated annual operating cost of a covered product during a representative average use cycle or period of use and not be unduly burdensome to conduct. (42 U.S.C. 6293(b)(3)) Under 42 U.S.C. 6314, the statute sets forth the criteria and procedures DOE must follow when prescribing or amending test procedures for covered equipment, reciting similar requirements at 42 U.S.C. 6314(a)(2).

In addition, the Energy Independence and Security Act of 2007 amended EPCA to require that DOE amend its test procedures for all covered consumer products to integrate measures of standby mode and off mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) Standby mode and off mode energy consumption must be incorporated into the overall energy efficiency, energy consumption, or other energy descriptor for each covered product, unless the current test procedure already accounts for and incorporates the standby mode and off mode energy consumption, or if such integration is technically infeasible. (42 U.S.C. 6295(gg)(2)(A)(i)-(ii)) If an integrated test procedure is technically infeasible, DOE must prescribe separate standby mode and off mode energy use test procedures for the covered product, if a separate test is technically feasible. (42 U.S.C. 6295(gg)(2)(A)(ii))) Any such amendment must consider the most current versions of the International Electrotechnical Commission (IEC) Standard 62301

and IEC Standard 62087,

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

IEC 62301,

Household electrical appliances—Measurement of standby power

(Edition 2.0, 2011-01).

IEC 62087,

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

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

The American Energy Manufacturing Technical Corrections Act (AEMTCA), Public Law 112-210, further amended

EPCA to require that DOE establish a uniform efficiency descriptor and accompanying test methods to replace the energy factor (EF) metric for covered consumer water heaters and the thermal efficiency (TE) and standby loss (SL) metrics for commercial water-heating equipment

within one year of the enactment of AEMTCA. (42 U.S.C. 6295(e)(5)(B)-(C)) The uniform efficiency descriptor and accompanying test method were required to apply, to the maximum extent practicable, to all water-heating technologies in use at the time and to future water-heating technologies, but could exclude specific categories of covered water heaters that do not have residential uses, can be clearly described, and are effectively rated using the TE and SL descriptors. (42 U.S.C. 6295(e)(5)(F) and (H)) In addition, beginning one year after the date of publication of DOE's final rule establishing the uniform descriptor, the efficiency standards for covered water heaters were required to be denominated according to the uniform efficiency descriptor established in the final rule (42 U.S.C. 6295(e)(5)(D)); and for affected covered water heaters tested prior to the effective date of the test procedure final rule, DOE was required to develop a mathematical factor for converting the measurement of their energy efficiency from the EF, TE, and SL metrics to the new uniform energy descriptor. (42 U.S.C. 6295(e)(5)(E)(i)-(ii))

The initial thermal efficiency and standby loss test procedures for commercial water heating equipment (including residential-duty commercial water heaters) were added to EPCA by the Energy Policy Act of 1992 (EPACT 1992), Public Law 102-486, and corresponded to those referenced in the ASHRAE and Illuminating Engineering Society of North America (IESNA) Standard 90.1-1989 (

i.e.,

ASHRAE Standard 90.1-1989). (42 U.S.C. 6314(a)(4)(A)) DOE subsequently updated the commercial water heating equipment test procedures on two separate occasions—once in a direct final rule published on October 21, 2004, and again in a final rule published on May 16, 2012. These rules incorporated by reference certain sections of the latest versions of American National Standards Institute (ANSI) Standard Z21.10.3,

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

available at the time (

i.e.,

ANSI Z21.10.3-1998 and ANSI Z21.10.3-2011, respectively). 69 FR 61974, 61983 (Oct. 21, 2004) and 77 FR 28928, 28996 (May 16, 2012).

EPCA also requires that, at least once every seven years, DOE evaluate test procedures for each type of covered product and covered equipment, including consumer water heaters and residential-duty commercial water heaters, to determine whether amended test procedures would more accurately or fully comply with the requirements for the test procedures to not be unduly burdensome to conduct and be reasonably designed to produce test results that reflect energy efficiency, energy use, and estimated operating costs during a representative average use cycle (or additionally, period of use for consumer products). (42 U.S.C. 6293(b)(1)(A); 42 U.S.C. 6314(a)(1)(A))

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

Federal Register

proposed test procedures and afford interested persons an opportunity to present oral and written data, views, and arguments with respect to such procedures. (42 U.S.C. 6293(b)(2); 42 US.C. 6314(b)) The comment period on a proposed rule to amend a test procedure shall be at least 60 days

and may not exceed 270 days. (42 U.S.C. 6293(b)(2)) In prescribing or amending a test procedure, the Secretary shall take into account such information as the Secretary determines relevant to such procedure, including technological developments relating to energy use or energy efficiency of the type (or class) of covered products involved. (42 U.S.C. 6293(b)(2)) If DOE determines that test procedure revisions are not appropriate, DOE must publish in the

Federal Register

its determination not to amend the test procedures. (42 U.S.C. 6293(b)(1)(A)(ii); 42 U.S.C. 6314(a)(1)(A)(ii)) DOE is publishing this final rule in satisfaction of the 7-year review requirement specified in EPCA. (42 U.S.C. 6293(b)(1)(A) and 42 U.S.C. 6314(a)(1)(A))

For covered equipment, if the Secretary determines that a test procedure amendment is warranted, the Secretary must publish proposed test procedures in the

Federal Register

and afford interested persons an opportunity (of not less than 45 days' duration) to present oral and written data, views, and arguments on the proposed test procedure. (42 U.S.C. 6314(b))

B. Background

The following discussion provides a brief history of the current rulemaking, which considers potential amendments to the test procedure for consumer water heaters and residential-duty commercial water heaters.

On April 16, 2020, DOE published in the

Federal Register

a request for information (April 2020 RFI) seeking comments on the existing DOE test procedure for consumer water heaters and residential-duty commercial water heaters. 85 FR 21104. The April 2020 RFI discussed a draft version of the American National Standards Institute (ANSI)/American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) Standard 118.2, “Method of Testing for Rating Residential Water Heaters and Residential-Duty Commercial Water Heaters,” published in March 2019 (March 2019 ASHRAE Draft 118.2), which is very similar to the existing DOE test procedure for consumer water heaters and residential-duty commercial water heaters. 85 FR 21104, 21108-21110 (April 16, 2020).

For a more complete history of earlier rulemaking efforts to develop the energy conservation standards and test procedure for consumer water heaters and residential-duty commercial water heaters, please consult the January 11, 2022 NOPR.

See

87 FR 1554, 1556-1558.

In the April 2020 RFI, DOE requested comments, information, and data about a number of issues, including: (1) differences between the March 2019 ASHRAE Draft 118.2 and the existing DOE test procedure; (2) test tolerances for supply water temperature, ambient temperature, relative humidity, voltage, and gas pressure; (3) the location of the instrumentation that measures water volume or mass; and (4) how to test certain types of consumer water heaters that cannot be easily tested to the existing DOE test procedure (

i.e.,

recirculating gas-fired instantaneous water heaters, water heaters that cannot deliver water at 125 degrees Fahrenheit (°F) ±5 °F, and water heaters with storage volumes greater than 2 gallons that cannot have their internal tank temperatures measured).

Id.

at 85 FR 21109-21114.

DOE subsequently published in the

Federal Register

a notice of proposed rulemaking on January 11, 2022 (January 2022 NOPR) in which the Department proposed to update appendix E, and related sections of the CFR, as follows:

(1) Incorporate by reference current versions of industry standards referenced by the current and proposed DOE test procedures: ASHRAE Standard 41.1,

ASHRAE Standard 41.6,

the pending update to ASHRAE Standard 118.2

(contingent on it being substantively the same as the draft which was under review), ASTM International (ASTM) Standard D2156,

and ASTM Standard E97.

ASHRAE Standard 41.1-2020, “Standard Methods for Temperature Measurement,” approved June 30, 2020.

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

ASHRAE Standard 118.2-2022, “Method of Testing for Rating Residential Water Heaters and Residential-Duty Commercial Water Heaters,” ANSI approved March 1, 2022.

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

ASTM Standard E97-1987 (W 1991), “Standard Test Methods for Directional Reflectance Factor, 45-

Deg 0-Deg, of Opaque Specimens by Broad-Band Filter Reflectometry,” approved January 1987, withdrawn 1991. Referenced by ASTM Standard D2156-09 (RA 2018).

(2) Add definitions for “circulating water heater,” “low temperature water heater,” and “tabletop water heater.”

(3) Specify how a mixing valve should be installed when the water heater is designed to operate with one.

(4) Modify flow rate requirements during the first-hour rating (FHR) test for water heaters with a rated storage volume less than 20 gallons.

(5) Modify timing of the first measurement in each draw of the 24-hour simulated-use test.

(6) Clarify the determination of the first recovery period.

(7) Clarify the mass of water to be used to calculate recovery efficiency.

(8) Modify the terminology throughout appendix E to explicitly state “non-flow activated” and “flow-activated” water heater, where appropriate.

(9) Clarify the descriptions of defined measured values for the standby period measurements.

(10) Modify the test condition specifications and tolerances, including electric supply voltage tolerance, ambient temperature, ambient dry-bulb temperature, ambient relative humidity, standard temperature and pressure definition, gas supply pressure, and manifold pressure.

(11) Add provisions to address gas-fired water heaters with measured fuel input rates that deviate from the certified input rate.

(12) Clarify provisions for calculating the volume or mass delivered.

(13) Add specifications for testing for the newly defined “low temperature water heaters.”

(14) Clarify testing requirements for the heat pump part of a split-system heat pump water heater.

(15) Define the use of a separate unfired hot water storage tank for testing water heaters designed to operate with a separately sold hot water storage tank.

(16) Clarify that any connection to an external network or control be disconnected during testing.

(17) Add procedures for estimating internal stored water temperature for water heater designs in which the internal tank temperature cannot be directly measured.

(18) Modify the provisions for untested water heater basic models within 10 CFR 429.70(g) to include electric instantaneous water heaters.

87 FR 1554, 1558.

A correction was published in the

Federal Register

on January 19, 2022, to properly reflect the date of the public meeting to discuss the January 2022 NOPR. 87 FR 2731.

DOE held a public meeting related to the January 2022 NOPR on January 27, 2022 (hereinafter, the NOPR public meeting).

On July 14, 2022, DOE published a supplemental notice of proposed rulemaking in the

Federal Register

(July 2022 SNOPR), that proposed to maintain the proposals from the January 2022 NOPR but with modifications discussed in the July 2022 SNOPR. 87 FR 42270. Specifically, the July 2022 SNOPR proposed to further update appendix E and related sections of the CFR by:

(1) Additionally requiring that, for water heaters with rated storage volume less than 2 gallons and a rated maximum gallons per minute (Max GPM or maximum GPM) of less than 1 gallon per minute, the flow rate tolerance shall be ±25 percent of the rated Max GPM.

(2) Allowing optional efficiency representations at alternative test conditions for heat pump water heaters.

(3) Adding a definition for “split-system heat pump water heaters” to distinguish these from circulating heat pump water heaters (

i.e.,

“heat pump-only” water heaters).

(4) Requiring gas-fired circulating water heaters to be tested using an unfired hot water storage tank (UFHWST) with a storage volume between 80 and 120 gallons and meets but does not exceed the minimum energy conservation standards (based on R-value) required at 10 CFR 431.110(a), and that circulating heat pump water heaters be tested using a 40-gallon electric resistance water heater at the minimum UEF standard required at 10 CFR 430.32(d).

(5) Requiring that water heaters (with the exception of demand-response water heaters) with user-selectable modes to “overheat” the water stored in the tank to increase effective capacity be tested at the highest internal tank temperature that can be achieved while maintaining the outlet water temperature at 125 °F ±5 °F. (If no such overheated mode exists, the unit is to be tested in a default mode.)

(6) Defining “demand-response water heater” based on the U.S. Environmental Protection Agency (EPA) ENERGY STAR Product Specification for Residential Water Heaters Version 5.0 (ENERGY STAR Water Heaters Specification v5.0)

definition for “connected water heating product,” with the additional requirement that demand-response water heaters cannot overheat as a result of user-initiated operation.

EPA published the ENERGY STAR Water Heater Specification v5.0 on July 18, 2022. The ENERGY STAR Water Heater Specification v5.0 is available online at:

www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd

(Last accessed on July 25, 2022).

(7) Establishing a metric and method for determining the effective storage volume.

(8) Adopting a method of determining the internal storage tank temperature for certain water heaters which cannot be directly measured using draws at the beginning and end of the 24-hour simulated-use test. 87 FR 42270, 42273-42274 (July 14, 2022).

This final rule responds to comments received in response to the January 2022 NOPR that were not addressed in the July 2022 SNOPR and comments received in response to the July 2022 SNOPR. Table I.1 presents the list of commenters who provided written submissions and/or oral statements at the NOPR public meeting which are addressed in this final rule.

Table I.1—List of Commenters With Written Submissions Addressed in This Final Rule

Commenter(s)

Reference in this final rule

Comment No. in the docket

Commenter type

A.O. Smith Corporation

A.O. Smith

NOPR No. 37; Transcript*; SNOPR No. 51*

Manufacturer.

Air Conditioning, Heating, and Refrigeration Institute

AHRI

NOPR No. 40; Transcript; SNOPR No. 55

Manufacturer Trade Association.

American Public Gas Association

APGA

NOPR No. 38

Utility Trade Association.

Appliance Standards Awareness Project

ASAP

Transcript

Efficiency Advocacy Organization.

Appliance Standards Awareness Project, American Council for an Energy-Efficient Economy, National Consumer Law Center (on behalf of its low-income clients)

ASAP, ACEEE, and NCLC

NOPR No. 34

Efficiency Advocacy Organizations.

Appliance Standards Awareness Project, American Council for an Energy-Efficient Economy, Natural Resources Defense Council

ASAP, ACEEE, and NRDC

SNOPR No. 54

Efficiency Advocacy Organizations.

Applied Energy Technology Company

AET

NOPR No. 29

Testing Laboratory.

Bradford White Corporation

BWC

NOPR No. 33; SNOPR No. 48

Manufacturer.

Edison Electric Institute

EEI

Transcript

Utility Trade Association.

GE Appliances

GEA

SNOPR No. 53

Manufacturer.

Jim Lutz

Lutz

NOPR No. 35

Individual.

Nathan Dyson

Dyson

NOPR No. 28

Individual.

New York State Energy Research and Development Authority

NYSERDA

NOPR No. 32; SNOPR No. 50

State Agency.

Northwest Energy Efficiency Alliance

NEEA

NOPR No. 30; SNOPR No. 56

Efficiency Advocacy Organization.

Nyle Water Heating Systems, LLC

Nyle

SNOPR No. 57

Manufacturer.

Pacific Gas and Electric Company, San Diego Gas and Electric, and Southern California Edison, collectively referred to as the “California Investor-Owned Utilities”

CA IOUs

NOPR No. 36; SNOPR No. 52

Utilities.

Rheem Manufacturing Company

Rheem

NOPR No. 31; Transcript; SNOPR No. 47

Manufacturer.

SEA Groups, Ltd

SEA

NOPR No. 24

Manufacturer.

Stone Mountain Technologies, Inc

SMTI

SNOPR No. 49

Manufacturer.

Note:

The January 27, 2022 TP NOPR Pubic Meeting Transcript can be found in the docket for this rulemaking at

www.regulations.gov

under entry number EERE-2019-BT-TP-0032-0027. Comments arising from the public meeting will be cited as follows: (Commenter name, Jan. 27, 2022 Public Meeting Transcript, No. 27 at p. X).

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

To the extent that interested parties have provided written comments that are substantively similar to any oral comments provided during the NOPR public meeting, DOE cites the written comments throughout this final rule. Any oral comments provided during the webinar that are substantively distinct from a submitter's written comments are summarized and cited separately throughout this final rule.

The parenthetical reference provides a reference for information located in the docket of DOE's rulemaking to develop test procedures for consumer water heaters and residential-duty commercial water heaters. (Docket No. EERE-2019-BT-TP-0032, which is maintained at

www.regulations.gov

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

APGA commented that DOE should adopt changes to its rulemaking process as outlined in a report by National Academies of Sciences, Engineering, and Medicine (NASEM) for both test procedures and standards. (APGA, No. 38 at p. 2) In response, the Department notes that the rulemaking process for test procedures of covered products and equipment are outlined at appendix A to subpart C of 10 CFR part 430, and DOE periodically examines and revises these provisions in separate rulemaking proceedings.

Section II of this document provides a synopsis of this final rule, and section III of this document discusses each amendment to the test procedure for consumer water heaters and residential-duty commercial water heaters in detail.

II. Synopsis of the Final Rule

In this final rule, DOE amends appendix E and related sections of the CFR. In summary, the final rule:

1. Incorporates by reference current versions of industry standards: ASHRAE 41.1, ASHRAE 41.6, ASHRAE 118.2, ASTM D2156, and ASTM E97.

2. Adds definitions for “circulating water heater, “tabletop water heater, and “low-temperature water heater.

3. Harmonizes various aspects of the DOE test procedure with industry test procedures ASHRAE 118.2-2022 and NEEA Advanced Water Heating Specification v8.0.

4. Modifies the test condition specifications and tolerances, including electric supply voltage tolerance, ambient conditions (ambient dry-bulb temperature and ambient relative humidity), standard temperature and pressure definition, gas supply pressure, manifold pressure, inlet water temperature, and flow rate tolerances, and adds optional test conditions for heat pump water heaters.

5. Specifies and clarifies methods for mixing valve installation for affected water heaters, orifice modification, and calculation of volume or mass delivered.

6. Defines the use of a separate unfired hot water storage tank or separate electric storage water heater for testing water heaters designed to operate with a separately sold tank.

7. Adds procedures for estimating internal stored water temperature for water heater designs in which the internal tank temperature cannot be directly measured.

8. Clarifies test procedures for water heaters with network connection capabilities.

9. Clarifies test procedures for flow-activated water heaters and water heaters that are not flow-activated by aligning terminology.

10. Includes additional testing provisions for electric resistance water heaters undergoing optional high temperature testing.

11. Includes a calculation for determining the effective storage volume of a water heater.

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

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

DOE test procedure prior to amendment

Amended test procedure

Attribution

References the 1986 (Reaffirmed 2006) version of ASHRAE 41.1 for methods for temperature measurement

References the updated 2020 version of ASHRAE 41.1

Industry TP Update to ASHRAE 41.1.

The 1982 version of ASHRAE 41.6 for methods for humidity measurement is referenced within the 1986 version of ASHRAE 41.1

References the 2014 version of ASHRAE 41.6, which is referenced by ASHRAE 41.1-2020

Industry TP Update to ASHRAE 41.6.

References the 2009 version of ASTM D2156 for testing smoke density in flue gases from burning distillate fuels

References the version of ASTM D2156 that was reaffirmed in 2018

Industry TP Update to ASTM D2156.

The 1987 version of ASTM E97 for testing directional reflectance factor, 45-deg 0-deg, of opaque specimens by broad-band filter reflectometry is referenced within ASTM D2156-09

References the 1987 version of ASTM E97, which is referenced by ASTM D2156-09 (RA 2018)

Industry TP Update to ASTM E97.

Does not define a “circulating water heater” as used in 10 CFR 430.2

Adds a definition for “circulating water heater” to 10 CFR 430.2

Allow for testing certain consumer water heaters.

Does not define a “tabletop water heater” as used as a product class distinction at 10 CFR 430.32(d)

Adds a definition for “tabletop water heater” to 10 CFR 430.2

Reinstate definition inadvertently removed by previous final rule.

Interprets the upper limit for consumer electric heat pump water heaters to be 12 kW of input, with “commercial heat pump water heater” defined at 10 CFR 431.102 as having rated electric power input greater than 12 kW

Corrects the upper limit for consumer electric heat pump water heaters to 24 amperes at 250 volts of input and amends the definition for “commercial heat pump water heater” accordingly

Make consistent with statutory definition.

Does not address how to configure a water heater for test when a mixing valve is required for proper operation

Specifies how a mixing valve should be installed when the water heater is designed to operate with one

Method added by DOE to improve repeatability.

Requires the flow rate during the FHR test to be 1.0 ± 0.25 gpm (3.8 ± 0.95 L/min) for water heaters with a rated storage volume less than 20 gallons

Requires the flow rate during the FHR test to be 1.5 ± 0.25 gpm (5.7 ± 0.95 L/min) for water heaters with a rated storage volume less than 20 gallons

Harmonization with industry TP ASHRAE 118.2-2022.

Does not address the situation in which the first recovery ends during a draw when testing to the 24-hour simulated-use test

Clarifies that the first recovery period will extend to the end of the draw in which the first recovery ended, and that if a second recovery initiates prior to the end of the draw, that the second recovery is part of the first recovery period as well

Harmonization with industry TP ASHRAE 118.2-2022.

The recovery efficiency equation for storage-type water heaters refers to the mass of water removed from the start of the test to the end of the first recovery period

Clarifies that, for the calculation of recovery efficiency, the mass of water removed during the first recovery period includes water removed during all draws from the start of the test until the end of the first recovery period

Harmonization with industry TP ASHRAE 118.2-2022.

The procedures for the standby period after the last draw of the 24-hour simulated-use test allow for a recovery to occur at the end of the 8-hour standby period, which indicates that the power to the main burner, heating element, or compressor is not disabled

Clarifies the alternate approach to determine the energy consumed during the 24-hour simulated use test if a standby period occurs after the final draw of the test

Harmonization with industry TP ASHRAE 118.2-2022.

Appendix E uses the phrases “storage-type” and “instantaneous-type” to refer to “non-flow activated” and “flow-activated” water heaters, respectively

Uses the terms “non-flow activated” and “flow-activated” water heater, where appropriate

Clarification.

The descriptions for Q

su,0

, Q

su,f

su,0

su,f

, τ

stby,1

t,stby,1

, and

a,stby,1

only address when the standby period occurs between draw clusters 1 and 2

The descriptions for Q

su,0

, Q

su,f

su,0

su,f

, τ

stby,1

t,stby,1

, and

a,stby,1

are generalized to refer to the section where the standby period is determined

Clarification.

Specifies that the first required measurement for each draw of the 24-hour simulated-use test is 5 seconds after the draw is initiated

Specifies that the first required measurement for each draw of the 24-hour simulated-use test is 15 seconds after the draw is initiated

Method updated by DOE to reduce burden.

Requires the electric supply voltage to be within ±1 percent of the rated voltage for the entire test

Requires the electric supply voltage to be within ±2 percent of the rated voltage beginning 5 seconds after the start of a recovery and ending 5 seconds before the end of a recovery

Method updated by DOE to reduce burden.

Requires maintaining ambient temperature for non-heat pump water heaters within a range of 67.5 °F ± 2.5 °F

Requires maintaining the ambient temperature for non-heat pump water heaters within a range of 67.5 °F ± 5 °F, and with an average of 67.5 °F ± 2.5 °F

Method updated by DOE to reduce burden.

Requires maintaining the dry-bulb temperature for heat pump water heaters within a range of 67.5 °F ± 1 °F

Requires maintaining the dry-bulb temperature for heat pump water heaters within a range of 67.5 °F ± 5 °F, and with an average of 67.5 °F ± 1 °F during recoveries and an average of 67.5 °F ± 2.5 °F when not recovering

Method updated by DOE to reduce burden.

Requires maintaining the relative humidity for heat pump water heaters within a range of 50 percent ±2 percent

Requires maintaining the relative humidity for heat pump water heaters within a range of 50 percent ±5 percent, and at an average of 50 percent ±2 percent during recoveries

Method updated by DOE to reduce burden

Requires that the heating value be corrected to a standard temperature and pressure, but does not state what temperature and pressure is standard or how to correct the heating value to the standard temperature and pressure

States that the standard temperature is 60 °F (15.6 °C) and the standard pressure is 30 inches of mercury column (101.6 kPa). Provides a method for converting heating value from the measured to the standard conditions via incorporation by reference of ASHRAE 118.2-2022

Harmonization with industry TP ASHRAE 118.2-2022.

Requires that the manifold pressure be within ±10 percent of the manufacturer recommended value

Clarifies that the manifold pressure tolerance applies only to water heaters with a pressure regulator that can be adjusted. Requires that the manifold pressure be within the greater of ±10 percent of the manufacturer recommended value or ±0.2 inches water column

Method updated by DOE to reduce burden.

Does not specify the input rate at which the gas supply pressure tolerance is determined

Specifies that the gas supply pressure tolerance is to be maintained when operating at the maximum input rate

Method added by DOE to clarify enforcement test procedure.

Does not contain procedures for modifying the orifice of a water heater that is not operating at the manufacturer specified input rate

Adds provisions regarding the modification of the orifice

Method added by DOE to clarify enforcement test procedure.

Does not specify how to calculate the mass removed from the water heater when mass is calculated indirectly using density and volume measurements

Specifies how to calculate the mass of water indirectly using density and volume measurements

Method added by DOE to improve repeatability.

Does not accommodate testing of “low-temperature water heaters” in appendix E

Adds a definition of “low-temperature water heater” in 10 CFR 430.2 and requires low temperature water heaters to be tested to their maximum possible delivery temperature in appendix E

Allow for testing certain consumer water heaters.

Does not explicitly define the test conditions required for each part of a split-system heat pump water heater

Explicitly states that the heat pump part of a split-system heat pump water heater is tested at the dry-bulb temperature and relative humidity conditions required for heat pump water heaters, and that the storage tank is tested at the ambient temperature and relative humidity conditions required for non-heat pump water heaters

Method added by DOE to improve representativeness and repeatability.

Does not accommodate testing of water heaters that require a separately-sold hot water storage tank to properly operate

Requires that gas-fired circulating water heaters be tested using a UFHWST with a storage volume between 80 and 120 gallons and that meets but does not exceed the minimum energy conservation standards required according to 10 CFR 431.110(a), and that heat pump circulating water heaters be tested using a 40-gallon electric storage water heater at the minimum UEF standard required at 10 CFR 430.32(d)

Allow for testing certain consumer water heaters.

Does not address water heaters with network connection capabilities

Explicitly states that any connection to an external network or control be disconnected during testing

Clarification.

Does not accommodate certain water heaters for which the mean tank temperature cannot be directly measured

Establishes a method of determining the internal storage tank temperature using draws at the beginning and end of the 24-hour simulated use test

Allow for testing certain consumer water heaters.

10 CFR 429.70(g) does not allow untested electric instantaneous water heaters to be certified, but does allow untested electric storage water heaters to be certified

Extends the untested provisions within 10 CFR 429.70(g) to include electric instantaneous water heaters

AEDM allowed by DOE to reduce burden.

Does not specify flow rate tolerance for water heaters with rated storage volume less than 2 gallons

Specifies that flow rates for all water heaters with rated storage volume less than 2 gallons must be maintained within a tolerance of ±0.25 gallons per minute. Additionally proposes that for water heaters with rated storage volume less than 2 gallons and a rated Max GPM of less than 1 gallon per minute, the flow rate tolerance shall be ±25 percent of the rated Max GPM

Method added by DOE to improve repeatability and reproducibility.

Does not include optional efficiency representations at alternative test conditions for heat pump water heaters

Allows for optional efficiency representations at alternative test conditions for heat pump water heaters

Harmonization with industry TP NEEA Advanced Water Heating Specification v8.0.

Does not include a definition for “split-system heat pump water heater.”

Adds a definition for “split-system heat pump water heater” to distinguish these from heat pump-only water heaters

Harmonization with industry TP NEEA Advanced Water Heating Specification v8.0.

Specifies that water heaters with multiple modes of operation be tested in the “default” or other similarly named mode

Provides a test method for electric resistance water heaters subject to high temperature testing (setting the water heater to the highest storage tank temperature and using a mixing valve to temper the delivery water to be within 125 ± 5 °F). Does not require the use of this type of testing for any water heaters, however, until compliance with amended standards is required

Method added by DOE to improve representativeness.

Does not include any method to determine effective storage volume of storage-type water heaters or circulating water heaters

Establishes a metric and method for determining the effective storage volume of storage-type water heaters and circulating water heaters

Method added by DOE which adopts a metric for additional consumer information.

Does not include a definition for “thermal break.”

Adopts a definition for “thermal break” but does not mandate the use of this component in test set-up

Harmonization with industry TP ASHRAE 118.2-2022.

DOE has determined that the amendments described in section III and adopted in this document will not alter the measured efficiency of consumer water heaters and residential-duty commercial water heaters, or require retesting or recertification solely as a result of DOE's adoption of the amendments to the test procedures. Discussion of DOE's actions are addressed in detail in section III of this document.

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

Federal Register

. Representations of energy use or energy efficiency must be based on testing in accordance with the amended test procedures beginning 180 days after the publication of this final rule for consumer water heaters and 360 after the publication of this final rule for residential-duty commercial water heaters.

III. Discussion

A. Scope of Applicability and Definitions

This document covers those products that meet the definition of consumer “water heaters,” as defined in the statute at 42 U.S.C. 6291(27), as codified at 10 CFR 430.2. This document also covers commercial water heating equipment with residential applications ((

i.e.,

those water heaters which meet the definition of “residential-duty commercial water heater” at 10 CFR 431.102).

In the context of covered consumer products, EPCA defines “water heater” as a product which utilizes oil, gas, or electricity to heat potable water for use outside the heater upon demand, including—

(a) Storage type units which heat and store water at a thermostatically controlled temperature, including gas storage water heaters with an input of 75,000 Btu per hour or less, oil storage water heaters with an input of 105,000 Btu per hour or less, and electric storage water heaters with an input of 12 kilowatts or less;

(b) Instantaneous type units which heat water but contain no more than one gallon of water per 4,000 Btu per hour of input, including gas instantaneous water heaters with an input of 200,000 Btu per hour or less, oil instantaneous water heaters with an input of 210,000 Btu per hour or less, and electric instantaneous water heaters with an input of 12 kilowatts or less; and

(c) Heat pump type units, with a maximum current rating of 24 amperes at a voltage no greater than 250 volts, which are products designed to transfer thermal energy from one temperature level to a higher temperature level for the purpose of heating water, including all ancillary equipment such as fans, storage tanks, pumps, or controls

necessary for the device to perform its function.

(42 U.S.C. 6291(27); 10 CFR 430.2)

In addition, at 10 CFR 430.2, DOE defines several specific categories of consumer water heaters, as follows:

(1) “Electric instantaneous water heater” means a water heater that uses electricity as the energy source, has a nameplate input rating of 12 kW or less, and contains no more than one gallon of water per 4,000 Btu per hour of input.

(2) “Electric storage water heater” means a water heater that uses electricity as the energy source, has a nameplate input rating of 12 kW or less, and contains more than one gallon of water per 4,000 Btu per hour of input.

(3) “Gas-fired instantaneous water heater” means a water heater that uses gas as the main energy source, has a nameplate input rating less than 200,000 Btu/h, and contains no more than one gallon of water per 4,000 Btu per hour of input.

(4) “Gas-fired storage water heater” means a water heater that uses gas as the main energy source, has a nameplate input rating of 75,000 Btu/h or less, and contains more than one gallon of water per 4,000 Btu per hour of input.

(5) “Grid-enabled water heater” means an electric resistance water heater that—

(a) Has a rated storage tank volume of more than 75 gallons;

(b) Is manufactured on or after April 16, 2015;

(d) Bears a permanent label applied by the manufacturer that—

(i) Is made of material not adversely affected by water;

(ii) Is attached by means of non-water-soluble adhesive; and

(iii) Advises purchasers and end-users of the intended and appropriate use of the product with the following notice printed in 16.5 point Arial Narrow Bold font: “IMPORTANT INFORMATION: This water heater is intended only for use as part of an electric thermal storage or demand response program. It will not provide adequate hot water unless enrolled in such a program and activated by your utility company or another program operator. Confirm the availability of a program in your local area before purchasing or installing this product.”

(6) “Oil-fired instantaneous water heater” means a water heater that uses oil as the main energy source, has a nameplate input rating of 210,000 Btu/h or less, and contains no more than one gallon of water per 4,000 Btu per hour of input.

(7) “Oil-fired storage water heater” means a water heater that uses oil as the main energy source, has a nameplate input rating of 105,000 Btu/h or less, and contains more than one gallon of water per 4,000 Btu per hour of input.

The definition for “grid-enabled water heater” includes the term “activation lock,” which is defined to mean a control mechanism (either by a physical device directly on the water heater or a control system integrated into the water heater) that is locked by default and contains a physical, software, or digital communication that must be activated with an activation key to enable the product to operate at its designed specifications and capabilities and without which the activation of the product will provide not greater than 50 percent of the rated first-hour delivery of hot water certified by the manufacturer. 10 CFR 430.2. As specified in this definition, the control mechanism must be physically incorporated into the water heater or, if a control system, integrated into the water heater to qualify as an activation lock. DOE is aware of certain State programs that encourage water heaters to be equipped with communication ports that allow for demand-response communication between the water heater and the utility.

DOE notes that presence of such a communication port, in and of itself, would not qualify as an activation lock for the purpose of classifying a water heater as a grid-enabled water heater. Demand-response water heaters are discussed separately in section III.A.1 of this final rule.

On May 7, 2019, the State of Washington signed House Bill 1444 which amended the Revised Code of Washington (RCW) (

i.e.,

the statutory code in the State of Washington), Title 19, Chapter 19.260 (RCW 19.260). On January 6, 2020, the State of Washington amended the Washington Administrative Code (WAC) (

i.e.,

the regulatory code in the State of Washington), Title 194, Chapter 194-24 (WAC 194-24) (Washington January 2020 Amendment) to align with RCW 19.260. Similarly, the State of Oregon published a final rule (Oregon August 2020 final rule) on August 8, 2020, which amended the Oregon Administrative Rules (OAR), Chapter 330, Division 92 (OAR-330-092). The Washington House Bill 1444 and the Oregon August 2020 final rule established a definition for electric storage water heater (RCW 19.260.020(14); OAR-330-092-0010(10)), an effective date of January 1, 2021 in Washington and January 1, 2022 in Oregon (RCW 19.260.080(1); OAR-330-092-0015(17)), a requirement that electric storage water heaters must have a modular demand response communications port compliant with the March 2018 version of the ANSI/CTA-2045-A communication interface standard, or a standard determined to be equivalent (RCW 19.260.080(1)(a)-(b); OAR-330-092-0020(17)), and, in Oregon, must bear a label or marking on the products stating either “DR-ready: CTA-2045-A” or “DR-ready: CTA-2045-A and [equivalent DR system protocol]” (OAR-330-092-0045(17)).

Additionally, as discussed further in section III.A.3 of this document, the appendix E test procedure also applies to residential-duty commercial water heaters. (

See

10 CFR 431.106(b)(1)) DOE defines these equipment categories at 10 CFR 431.102 as any gas-fired storage, oil-fired storage, or electric instantaneous commercial water heater that meets the following conditions:

(1) For models requiring electricity, uses single-phase external power supply;

(2) Is not designed to provide outlet hot water at temperatures greater than 180 °F; and

(3) Does not meet any of the following criteria:

Water heater type

Indicator of non-residential application

Gas-fired Storage

Rated input >105 kBtu/h; Rated storage volume >120 gallons.

Oil-fired Storage

Rated input >140 kBtu/h; Rated storage volume >120 gallons.

Electric Instantaneous

Rated input >58.6 kW; Rated storage volume >2 gallons.

In the January 2022 NOPR, DOE discussed definitions and the scope of appendix E for heat pump water heaters (electric as well as gas-fired), gas-fired instantaneous water heaters (specifically circulating gas-fired water heaters), tabletop water heaters, and residential-duty commercial water heaters. 87 FR 1554, 1560-1567 (Jan. 11, 2022). Additionally, DOE proposed a new definition for “demand-response water heater” in the July 2022 SNOPR. 87 FR 42270, 42280 (July 14, 2022).

BWC generally agreed with DOE's determinations regarding product and equipment definitions and classifications. (BWC, No. 33 at p. 1) AET generally commented that DOE's test procedures should be appropriate for all consumer water heaters within the scope of standards, especially for electric instantaneous water heaters. (AET, No. 29 at pp. 11-12)

As discussed throughout this rulemaking, it is DOE's intention to ensure that the appendix E test procedure amended by this final rule is appropriate and applicable to all consumer water heaters and residential-duty commercial water heaters. Sections III.A.1 through III.A.4 of this document address specific issues related to scope and definitions that either DOE requested comment on in the January 2022 NOPR or July 2022 SNOPR, or that were identified by commenters in response to those documents.

1. Demand-Response Water Heaters

Storage-type water heaters that have “connected” capability, often referred to as “demand-response” water heaters, can be remotely activated and/or deactivated by signals from a utility company or another program operator, and are able to serve as a thermal energy storage device. DOE considered whether specific testing requirements would be appropriate for demand-response water heaters (such as requiring measurement of the energy consumed by connected features, or providing a method for calculating the amount of thermal energy storage available); however, DOE had tentatively determined that additional test procedure provisions (such as the calculation of a thermal energy storage metric) are premature and unnecessary to specify at this time as the market continues to develop and evolve. DOE proposed only that a provision be added to the test procedure to require that if a water heater can connect to an external network or controller, that communication shall be disabled during testing. 87 FR 1554, 1585-1586 (Jan. 11, 2022). Several stakeholders provided input on this tentative determination.

NEEA encouraged DOE to adopt definitions and test methods for “connectable” water heaters in the test procedure. The commenter pointed to the following existing and emerging standards as references: Consumer Technology Association (CTA) Standard 2045 (ANSI/CTA-2045)/EcoPort,

U.S. Environmental Protection Agency (EPA) ENERGY STAR connected device requirements, and AHRI 1430,

Standard for Demand Response for Electric Water Heaters.

NEEA stated that definitions of connectivity have already been adopted by the States of Washington, Oregon, and California as part of their water heating appliance standards. (NEEA, No. 30 at pp. 2-3) The CA IOUs recommended the adoption of a definition for the communication capability for grid-enabled water heaters that is consistent with the Connected Product Criteria in the ENERGY STAR Product Specification for Residential Water Heaters.

The CA IOUs also recommended that DOE incorporate the associated ENERGY STAR connected products test procedure into the appendix E test procedure. (CA IOUs, No. 36 at pp. 2-3)

Available online at:

shop.cta.tech/products/https-cdn-cta-tech-cta-media-media-ansi-cta-2045-b-final-2022-pdf

(Last accessed on Sept. 17, 2022).

AHRI Standard 1430, “Standard for Demand Response for Electric Water Heaters,” was published in December 2022. It is an industry consensus standard developed by an AHRI Consensus Standards Project Committee that includes definitions, test requirements, operating and physical requirements, minimum data requirements for published ratings, marking and nameplate, and data and conformance conditions for demand-response electric water heaters. For more information, see

www.ahrinet.org/search-standards/ahri-1430-demand-flexible-electric-storage-water-heaters

(Last accessed on Feb. 17, 2023).

According to version 5.0 of the ENERGY STAR Program Requirements for Residential Water Heaters Eligibility Criteria, a “connected water heater product (CWHP)” includes the ENERGY STAR certified water heater, integrated or separate communications hardware, and additional hardware and software required to enable connected functionality. “Demand Response” is also defined by that source to mean changes in electric or gas usage by end-use customers from their normal consumption patterns in response to changes in the price of electricity or gas over time, or to incentive payments designed to induce lower electricity or gas use at times of high wholesale market prices or when system reliability is jeopardized. Version 5.0 of the ENERGY STAR specification is available online at:

www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd

(Last accessed on July 25, 2022).

In response, DOE considered these comments and also assessed the operation of demand-response water heaters as grid thermal energy storage devices using specific communication protocols in order to determine how to distinguish these products from other water heaters capable of storage tank overheating. On July 18, 2022, EPA published an ENERGY STAR Version 5.0 Residential Water Heater Specification, which included definitions for “connected water heater product” and “demand response.” These definitions included references to Consumer Technology Association (CTA) Standard 2045 (ANSI/CTA-2045),

a design standard for a communications module that allows a water heater to receive signals from a utility company (

e.g.,

a curtailment request). As indicated by NEEA and the CA IOUs, the presence of a CTA-2045 port uniquely enables a water heater to be able to participate in any demand-response program, and DOE has additionally determined that products with these features are increasing in number.

See

section 4.D.a of the ENERGY STAR Version 5.0 specification.

In the July 2022 SNOPR, DOE noted that certain new water heaters were available on the market that are shipped from the point of manufacture with a mixing valve installed and intentionally “overheat”

the water to a stored temperature that is higher than the delivery temperature setpoint to provide additional capacity.

87 FR 42270, 42279-42280 (July 14, 2022). DOE proposed specific test requirements for such products (see section III.E.1 of this document for discussion). DOE also noted that water heaters with demand-response capabilities may undergo utility-initiated overheating during certain periods to store additional energy in the water heater during peak demand periods, and tentatively determined that the test provisions proposed for water heaters that overheat may not be appropriate for demand-response water heaters that overheat.

Id.

To distinguish demand-response water heaters from other types capable of overheating, DOE proposed to define a “demand-response water heater” as follows:

The term “overheating” refers to raising the tank temperature above the outlet water setpoint and does not denote performance outside of the normal operating range of the water heater.

While typical water heaters do not store water warmer than the outlet temperature setpoint (which is, on average, 125 ± 5 °F), water heaters designed to increase energy storage capacity may overheat the tank to temperatures such as 140-150 °F and use a mixing valve to temper the outlet water down to the setpoint condition. The energy storage capacity is proportional to both the size of the tank and the temperature of the water within.

Demand-response water heater

means a storage-type water heater that—

1. Has integrated communications hardware and additional hardware and software required to enable connected functionality with a utility or third party, that dispatches signals with demand response instructions and/or price signals to the product and receives messages from the demand-response water heater;

2. Meets the communication and equipment standards for Consumer Technology Association (CTA) Standard 2045-B (ANSI/CTA-2045-B);

ANSI/CTA-2045-B, “Modular Communications Interface for Energy Management,” published February 2021. (Available at:

shop.cta.tech/products/https-cdn-cta-tech-cta-media-media-ansi-cta-2045-b-final-2022-pdf

) (Last accessed Sept. 17, 2022).

3. Automatically heats the stored water above the delivery temperature setpoint only in response to instructions received from a utility or third party.

87 FR 42270, 42280 (July 14, 2022). DOE sought comment on this proposed definition.

Id.

In response to the July 2022 SNOPR, AHRI, A.O. Smith, BWC, and Rheem recommended that DOE change its definition of “demand-response water heater” to be consistent with ENERGY STAR and AHRI Standard 1430.

(AHRI, No. 55 at p. 7; A.O. Smith, No. 51 at pp. 6-7; BWC, No. 48 at p. 2; Rheem, No. 47 at p. 6) Specifically, AHRI and A.O. Smith requested that DOE define “demand-flexible water heater” as “an electric resistance storage water heater or heat pump water heater with the capability to reduce, shed, shift, load up, and modulate energy consumption in response to a command or instructions received from a utility or third party.” (AHRI, No. 55 at p. 7; A.O. Smith, No. 51 at pp. 6-7) BWC requested that DOE use the ENERGY STAR and AHRI Standard 1430 definitions of “demand-response” to avoid manufacturer burden and allow for easier future development of these products. (BWC, No. 48 at p. 2) Rheem further recommended that DOE seek direct feedback from EPA's ENERGY STAR program. (Rheem, No. 47 at p. 6)

AHRI Standard 1430-2022 (I-P), “2022 Standard for Demand Flexible Water Heaters,” published December 2022. (Available at:

https://www.ahrinet.org/search-standards/ahri-1430-demand-flexible-electric-storage-water-heaters.

) (Last accessed Feb. 17, 2023)

NYSERDA pointed out that DOE's proposed definition for “demand-response water heater,” which states that it cannot overheat as a result of user-initiated operation, is an additional requirement beyond ENERGY STAR's definitions. Accordingly, NYSERDA urged DOE to define “overheating test exempt water heaters” so as to avoid creating market confusion, and the commenter recommended that DOE consider the power usage for connectedness as included in the ENERGY STAR water heater specification, as it would allow utilities to plan more effectively, encourage the additional load to be minimal, and inform consumers regarding anticipated operating costs. (NYSERDA, No. 50 at p. 2)

NEEA indicated support for DOE's proposed definition of “demand-response water heater” and the proposal for demand-response water heaters to meet the communication and equipment standards for ANSI/CTA-2045. (NEEA, No. 56 at pp. 2-3) AHRI, however, indicated that DOE's definition would require compliance with the demand-response program the water heater is enrolled in, whereas other, non-DOE definitions allow consumers to opt out. (AHRI, No. 55 at p. 7) BWC and Rheem requested that DOE remove the requirement to comply with CTA-2045. (BWC, No. 48 at pp. 1-2, Rheem, No. 47 at p. 6) BWC stated that requiring compliance with CTA-2045 may prevent manufacturers from designing their products around separate and future protocols. (BWC, No. 48 at pp. 1-2)

Rheem recommended that DOE's definition acknowledge the fact that many water heaters with demand-response capability are currently shipped without all necessary hardware to participate in a demand-response program. Rheem also suggested that DOE's definition does not cover most demand-response water heaters because it excludes water heaters without the ability to heat water above the setpoint. (Rheem, No. 47 at p. 6)

After reviewing these comments from stakeholders, DOE understands that, for the purpose of demand-response programs, utilities and manufacturers would benefit from a standardized definition of “demand-response water heater,” specifically one that requires certain communications protocols to be present in order to be compatible with the demand-response signals from the utility or third-party. Stakeholders have indicated that, in order to be deemed a “demand-response water heater,” a product must demonstrate that it is capable of executing the commands from the demand-response signals (

i.e.,

pass the verification tests in the ENERGY STAR Test Method to Validate Demand Response or in AHRI Standard 1430). However, DOE proposed a more limited definition for “demand-response water heater” in the July 2022 SNOPR, seeking only to describe the types of water heaters that could temporarily increase the storage tank temperature as a means to perform a load up

such that this particular operation would not be considered “overheating” in the appendix E test procedure (

see

87 FR 42270, 42280 (July 14, 2022)). This led DOE to revisit its proposed definition and to reassess its planned approach.

According to the ENERGY STAR Test Method to Validate Demand Response v1.2, a connected water heating product is required to use and/or store additional thermal energy that the device otherwise would not have used/stored under normal operation in response to a load up request. This allows the stored thermal energy to increase within the safety parameters determined by the manufacturer, and, for installations with a mixing valve, the device may exceed the user set point temperature.

As a result, in this final rule, DOE has decided not to establish a definition for “demand-response water heater.” DOE has considered the various requirements which stakeholders suggested should be criteria for a product to be called a “demand-response water heater” and has determined that, while standardization of these requirements may be beneficial to utilities and industry, it is unnecessary at this time because DOE can instead describe the types of water heaters that can temporarily increase the storage tank temperature only in response to instructions from a utility or third-party demand response program without defining “demand-response water heater”. Additionally, as discussed in section III.E.1.b of this document, this final rule only amends the test procedure to provide a means for testing water heaters in the highest tank temperature setting, and DOE is adopting it as a voluntary measure in this test procedure for certain electric storage water heaters. As such, it is no longer necessary to establish a definition for “demand-response water heater” in this test procedure rulemaking.

2. Heat Pump Water Heaters

As discussed in section III.A of this document, EPCA defines “water heater” to include, in relevant part, (A) storage type units which heat and store water at a thermostatically controlled temperature, including . . . electric storage water heaters with an input of 12 kilowatts or less; (B) instantaneous type units which heat water but contain no more than one gallon of water per 4,000 Btu per hour of input, including . . . electric instantaneous water heaters with an input of 12 kilowatts or less; and (C) heat pump type units, with a maximum current rating of 24 amperes at a voltage no greater than 250 volts, which are products designed to transfer thermal energy from one temperature level to a higher temperature level for the purpose of heating water, including all ancillary equipment such as fans, storage tanks, pumps, or controls necessary for the device to perform its function. (42 U.S.C. 6291(27))

Because the maximum current and voltage ratings for consumer heat pump type units are 24 amperes at no more than 250 volts, the maximum electrical input for this type of product is determined to be 6 kilowatts.

In this final rule, DOE is providing clarifications on how these definitions apply to electric and gas-fired heat pump storage water heaters.

Power equals current times voltage, so the definition of consumer heat pump type unit corresponds to a maximum power rating of 6,000 W, or 6 kW (

i.e.,

24 A times 250 V equals 6,000 W).

a. Electric Heat Pump Storage Water Heaters

EPCA is not explicit as to whether heat pump type units are considered a subcategory of storage type units and

instantaneous type units. “Storage type units” and “instantaneous type units” are not exclusive of “heat pump type units.” Based on the statute's “water heater” definition, an electric heat pump type unit could be covered under the “water heater” definition's description of storage type units (if it heats and stores water at a thermostatically controlled temperature with an input of 12 kilowatts or less) or instantaneous type unit (if it heats water and contains no more than one gallon of water per 4,000 Btu per hour of input and has an input of 12 kilowatts or less).

On November 10, 2016, DOE published a final rule in the

Federal Register

(the November 2016 Final Rule) that treated heat pump-type units as a subcategory of the other two types of units listed in the definition of water heater. Specifically, DOE stated in the November 2016 final rule that a heat pump water heater with a total rated input of less than 12 kilowatts would be a consumer water heater because EPCA classifies electric water heaters with less than 12 kilowatts rated electrical input as consumer water heaters. 81 FR 79261, 79301-79302. In the January 2022 NOPR, DOE responded to comments requesting clarification on whether electric heat pump water heaters between 6 kilowatts and 12 kilowatts of input should be classified as consumer water heaters or commercial water heaters. 87 FR 1554, 1561-1563 (Jan. 11, 2022). Upon further review of EPCA and the water heater market, DOE initially determined in the January 2022 NOPR that the interpretation presented in the November 2016 Final Rule was not the best reading of EPCA.

Id.

In the January 2022 NOPR, DOE explained that the structure of the statutory definition of “water heater” in the Energy Conservation Program for Consumer Products in Part A of EPCA lists each type of water heater at equal subparagraph designations. Therefore, when defining “water heater” for the purpose of determining whether a water heater is a consumer water heater, the energy use criteria specified for heat pump-type units is to be applied separately and distinctly from the criteria specified for the categorizations of storage-type units and instantaneous-type units. Therefore, DOE had tentatively determined that heat pump water heaters, which operate with a maximum current rating greater than 24 amperes or at a voltage greater than 250 volts, are more appropriately covered as commercial water heaters than consumer water heaters. 87 FR 1554, 1561-1562 (Jan. 11, 2022).

As explained in the January 2022 NOPR, there are three other reasons why DOE tentatively concluded that the revised interpretation would be more applicable to the residential water heater market.

First, heat pump technology is capable of providing heat output which exceeds the energy input. A heat pump type unit with an input rate of 12 kilowatts could have a heating capacity (

i.e.,

output capacity) of approximately 42 kilowatts, which is 3.6 times the output heating capacity provided by the largest possible consumer electric storage type water heater (

i.e.,

11.8 kilowatts).

While a heat pump-type unit with a 12 kilowatt input capacity could theoretically be designed and installed in a residential application, its water heating capacity (

i.e.,

output capacity) would far exceed the water heating demand of any residential installation. 87 FR 1554, 1562 (Jan. 11, 2022).

A 12-kW electric resistance water heater with an assumed recovery efficiency of 98 percent would have an output heating capacity of 11.8 kW (12 kW × 0.98 = 11.8 kW). An electric heat pump-type water heater with a 12-kW input capacity, with an assumed recovery efficiency of 350 percent, would have an output heating capacity of 42 kW (12 kW × 3.5 = 42 kW), which is 3.6 times greater than the 11.8 kW output heating capacity of an electric resistance water heater with equivalent input capacity.

Second, the DOE test procedure for consumer water heaters at the time of the November 2016 Final Rule only covered heat pump water heaters which have “a maximum current rating of 24 amperes (including the compressor and all auxiliary equipment such as fans, pumps, controls, and, if on the same circuit, any resistive elements) for an input voltage of 250 volts or less,” and, therefore, electric heat pump water heaters with greater than 24 amperes at 250 volts were not considered at the time when the current energy conservation standards for consumer water heaters were established (April 2010). As a result, these current standards do not reflect energy usage for heat pump water heaters between 6 kilowatts and 12 kilowatts, and such products are more appropriately rated to the commercial water heater test procedure (10 CFR 431.106) and evaluated against the maximum standby loss standards for this equipment (10 CFR 431.110(a)). 87 FR 1554, 1562 (Jan. 11, 2022).

Third, based on its review of the market, DOE is aware of integrated heat pump water heaters, split-system heat pump water heaters, and heat pump-only water heaters (

i.e.,

circulating heat pump water heaters) which are designed for use in residential applications, and all such products are rated at or below 24 A/250 V of input. Integrated heat pump water heaters, which consist of an air-source heat pump in one assembly with a storage tank, typically operate with 240-volt input. Although integrated heat pump water heaters usually have backup 4.5-kilowatt electric resistance heating elements, the elements do not operate simultaneously, which ensures that these products do not surpass 6 kilowatts of input or 24 A/250 V at any given time. Some integrated heat pump water heaters are designed to operate at only 120 volts of input (

i.e.,

“retrofit-ready,” “plug-in,” or “120-volt” heat pump water heaters). Split-system heat pump water heaters, which consist of a separate heat pump and storage tank that are sold together (where the heat pump components are usually situated outdoors), are also covered by the currently applicable appendix E test procedure and have electrical input ratings which do not exceed 24 A/250 V. Circulating heat pump water heaters (or “heat pump-only” water heaters), which consist of only a heat pump module and must be installed with a separate storage tank, similarly do not exceed this limit, and there are models of circulating heat pump water heaters which are intended to operate on 120 volts of input. Alternative source heat pump water heaters (

e.g.,

ground-source or water-source), were not considered in this rulemaking due to their predominant use as commercial products. 87 FR 1554, 1563 (Jan. 11, 2022).

In this final rule, DOE maintains the revised interpretation as discussed in the January 2022 NOPR. To clarify this interpretation in the regulatory definitions, DOE is amending the definition of “commercial heat pump water heater” at 10 CFR 431.102 to reflect this revised interpretation. The revised definition reads: “

Commercial heat pump water heater (CHPWH)

means a water heater (including all ancillary equipment such as fans, blowers, pumps, storage tanks, piping, and controls, as applicable) that uses a refrigeration cycle, such as vapor compression, to transfer heat from a low-temperature source to a higher-temperature sink for the purpose of heating potable water, and operates with a current rating greater than 24 amperes or a voltage greater than 250 volts. Such equipment includes, but is not limited to, air-source heat pump water heaters, water-source heat pump water heaters, and direct geo-exchange heat pump water heaters.”

In the April 2020 RFI, DOE requested feedback on the need for creating a separate definition for “electric heat pump storage water heater,” similar to the definition in the March 2019

ASHRAE Draft 118.2, or whether the current DOE definitions in 10 CFR 430.2 for “electric storage water heater” and “water heater,” which include “heat pump type units,” would adequately cover such products for the purpose of performing the DOE test procedure. 85 FR 21104, 21110 (April 16, 2020). The Department's tentative determination in the January 2022 NOPR was that a separate definition would not be needed because the current definitions were sufficient to describe these products. 87 FR 1554, 1563-1564 (Jan. 11, 2022). In response to the January 2022 NOPR, Rheem requested that the product class-specific definitions include or refer to the “heat pump type” requirements in EPCA. (Rheem, No. 31 at p. 2) BWC agreed with DOE's assessment that consumer heat pump water heaters operate at no greater than 24 amperes at 250 volts. (BWC, No. 33 at pp. 1-2)

Additionally, DOE received several comments on the January 2022 NOPR regarding definitions for specific types of heat pump water heaters used in residential applications.

The CA IOUs recommended that DOE should supplement its test procedure definitions to address heat pump water heaters rated to operate at 120 volts of input. More specifically, the CA IOUs recommended that DOE develop a separate definition for 120-volt heat pump water heaters in the test procedure and consider any distinguishing characteristics that might require changes to the test procedure to represent their real-world performance accurately. These commenters argued that a separate definition would allow for the possibility of separate energy conservation standards for these products. The CA IOUs stated that they expect the first 120-volt heat pump water heaters to appear on the retail market in 2022 and noted that the California Energy Commission recently adopted a goal to install six million heat pumps (for space and water heating) by 2030, many of which they anticipate will be 120-volt heat pump water heaters. (CA IOUs, No. 36 at p. 4)

AET expressed support for the inclusion of heat pump-only water heaters within the scope of the DOE test procedure but suggested revising the terminology so as to differentiate a “heat pump water heater without a tank” from a “heat pump water heater with a tank.” (AET, No. 29 at p. 2) On this point, DOE notes that there is not yet a particular term for these products defined at 10 CFR 430.2 or in appendix E. These products may be referred to using any of the terms mentioned by AET, but the clearest description of these products is “circulating heat pump water heaters.” Circulating water heaters are discussed further in section III.A.4.a of this document. DOE is adopting a definition for “circulating water heater” in this final rule, which will include these products.

Rheem recommended that DOE include split-system heat pump water heaters in the “water heaters requiring a storage tank” definition proposed in the January 2022 NOPR and that DOE define “integrated heat pump water heater” to distinguish them from split-system water heaters. (Rheem, No. 47 at p. 4) AHRI stated that a definition of “split-system water heater” is not required if DOE does not include the proposed optional additional test conditions in this rulemaking. (AHRI, No. 55 at p. 5)

In response to Rheem's comments, a split-system water heater is not necessarily a “water heater requiring a storage tank,” as proposed in the January 2022 NOPR, because for a water heater to meet the proposed definition of “water heater requiring a storage tank” would mean there is no storage tank specified or supplied by the manufacturer but that it requires one for testing and operation. A split-system water heater, however, may have a manufacturer supplied or specified tank and, as such, would not necessarily fall under the definition of a “water heater requiring a storage tank.” When the tank is specified or supplied by the manufacturer, that tank should be used for testing, rather than a water heater or storage tank that meets the default conditions that were proposed to be added in section 4.10 of appendix E. Additionally, in response to the suggestion that DOE define “integrated heat pump water heater,” DOE notes that, as discussed later in this section, it is modifying the definition of a “split-system water heater” based on comments to mean a heat pump-type water heater in which at least the compressor, which may be installed outdoors, is separate from the storage tank. Therefore, heat pump water heaters that do not fall under the definition of “split-system water heater” adopted in this final rule would be integrated heat pump water heaters, as the refrigeration components would be integrated with the tank. Thus, it is unnecessary to separately define “integrated heat pump water heaters,” and the term would not be used in the test method. Creating additional definitions for this configuration may lead to confusion. In response to AHRI's comment, as discussed and for the reasons explained in section III.C.7 of this document, DOE has decided to include the proposed optional additional test conditions in this rulemaking, and, thus, the Department has defined the term “split-system water heater.”

A.O. Smith requested that DOE clearly define “heat pump-only water heater” and elucidate how appendix E applies to them. (A.O. Smith, No. 51 at p. 5) BWC requested that DOE clarify in its definitions the difference between split-system and heat pump-only water heaters. (BWC, No. 48 at p. 1)

In response, a heat pump-only water heater is considered a circulating water heater, which is a type of heat pump water heater, falls under the circulating water heater product classes, and is covered under the associated provisions of appendix E. Such distinctions were previously discussed in the January 2022 NOPR. 87 FR 1554, 1565 (Jan. 11, 2022). These units have an input greater than or equal to 4,000 Btu per hour per gallon, and accordingly, they are considered instantaneous water heaters. In contrast, split-system heat pump water heaters (which, unlike heat pump-only units, are distributed with a storage tank) are considered storage water heaters.

After considering these comments, DOE has decided to affirm coverage in this test procedure final rule for all of the aforementioned types of consumer heat pump water heaters. In particular, DOE has determined that the current definitions of “heat pump-type” and “electric storage water heater” adequately cover the electric heat pump water heaters on the market that are representative of residential use (including, but not limited to, integrated 240-volt and 120-volt heat pump water heaters, split-system heat pump water heaters, and circulating heat pump water heaters), and that a separate definition for “electric heat pump water heaters” is not needed in order to appropriately characterize the test procedure for consumer water heaters and residential-duty commercial water heaters.

At the time of this final rule, DOE is only aware of a small number of 120-volt integrated heat pump water heaters and circulating heat pump water heaters on the market. Therefore, DOE has limited information to determine whether there are any distinguishing characteristics of these products which would necessitate tailored test procedure requirements in order to produce ratings that are representative, reproducible, and repeatable. One manufacturer has publicly certified

ratings

for 120-volt electric storage heat pump models using the currently applicable appendix E test procedure (without the use of a test procedure waiver), so DOE, therefore, concludes that the appendix E test procedure is appropriate and representative for these models. DOE is aware, however, that default mode operation of 120-volt electric storage heat pump water heaters may require raising the tank temperature above the delivery setpoint in order to meet consumer expectations of first hour rating (FHR), and further discussion of potential impacts of storage tank overheating on ratings for 120-volt electric storage heat pump water heaters as a result of this final rule's action can be found in section III.E.1 and III.J.3 of this document.

DOE reviewed public certification data in its Compliance Certification Management System (CCMS) database, found online at

www.regulations.doe.gov/certification-data/#q=Product_Group_s%3A*.

In response to the July 2022 SNOPR, which proposed optional ambient test conditions and new definitions for “split-system water heaters,” AHRI and A.O. Smith requested that DOE change its definition of “split-system water heater” to the definition used by ENERGY STAR, which specifies that the compressor, evaporator, and/or condenser are separated from a storage tank that is specified by the manufacturer and rated as a single system. (AHRI, No. 55 at p. 5; A.O. Smith, No. 51 at p. 4) A.O. Smith offered an alternative definition to DOE's earlier definition of “split-system heat pump water heater” which specified the heat pump as being an outdoor component. (A.O. Smith, No. 51 at pp. 4-5)

A.O. Smith, NEEA, and the CA IOUs stated that it is unnecessary for the definition of “split-system water heater” to specify the location of specific components and requested that DOE eliminate the distinction between indoor and outdoor components. (A.O. Smith, No. 51 at p. 5; CA IOUs, No. 52 at pp. 4-5; NEEA, No. 56 at p. 2) The CA IOUs stated that the compressor should be specified as the component separate from the storage tank, rather than the heat pump, to more generally reflect split-system water heaters. (CA IOUs, No. 52 at pp. 4-5)

NEEA additionally recommended that DOE should not include references to “indoor” or “outdoor” in its proposed definition of “split-system heat pump water heater,” as outdoor installation of the heat pump component does not necessarily follow the splitting of heating and storage functions into separate components, and an all-indoor split-system HPWH has the potential to provide significant benefits to consumers. NEEA added that adopting a split-system definition that excludes such products could hinder manufacturers in bringing them to market. (NEEA, No. 56 at p. 2) Similarly, Nyle commented that the proposed definition is problematic because not all split-system heat pump water heaters contain an outdoor component, noting that it manufactures a 120-volt heat pump water heater for indoor use only. Nyle suggested revising the definition to indicate that a split-system heat pump water heater means a heat pump-type water heater where the storage unit and heat pump components are independent from one another but must be connected to operate (

i.e.,

through refrigerant lines, water piping, or via a thermal storage device). (Nyle, No. 57 at p. 1)

In order to address the need for separate test conditions for split-system water heaters (see section III.C.7 of this document for a discussion on optional test conditions, which simulate different indoor and outdoor air conditions for the different components of a split-system water heater), DOE is adopting a definition for this subset of heat pump water heaters at 10 CFR part 430, subpart B, appendix E, section 1.14.

In response to these comments, DOE acknowledges that it is not necessary to specify the location of the components and/or the storage tank in the definition of “split-system heat pump water heater” as long as they are separate. Therefore, DOE has changed the definition of “split-system heat pump water heater” to mean a heat pump-type water heater in which at least the compressor, which may be installed outdoors, is separate from the storage tank. This definition still reflects that which is used in NEEA's Advanced Water Heating Specification (AWHS) version 8.0 (AWHS v8.0),

with minor modifications.

AWHS v8.0 was published by NEEA on March 1, 2022. Although early editions of the AWHS focused primarily on providing more representative performance metrics for heat pump water heaters in cold climates, the latest editions are now more broadly focused on providing representative performance metrics for heat pump water heaters across all climates. AWHS v8.0 includes separate test condition requirements for integrated and split-system heat pump water heaters. These test conditions are discussed further in detail in section III.C.1 of this final rule. (Available at:

neea.org/resources/advanced-water-heating-specification-v8.0

) (Last accessed on Sept. 19, 2022).

Additionally, a new definition for “circulating water heater” is being established in this final rule at 10 CFR 430.2, as discussed in section III.A.4.a of this document. This product category includes heat pump-only water heaters, which is also discussed in section III.A.4.a of this document. Specific testing provisions for circulating water heaters are being newly established in this final rule, as discussed in section III.D.4 of this document.

b. Gas-Fired Heat Pump Storage Water Heaters

The statutory definition for a “heat pump type” water heater (

see

42 U.S.C. 6291(27)(C)) is not specific to electric heat pump type water heaters. Gas-fired heat pump storage water heaters typically use an absorption or adsorption refrigeration cycle, driven by a gas burner, to transfer heat from the surrounding air to the water inside the water heater.

In the July 2014 Final Rule, DOE codified a definition for “gas-fired heat pump water heater” as follows:

Gas-fired heat pump water heater

means a water heater that uses gas as the main energy source, has a nameplate input rating of 75,000 Btu/h (79 MJ/h) or less, has a maximum current rating of 24 amperes (including all auxiliary equipment such as fans, pumps, controls, and, if on the same circuit, any resistive elements) at an input voltage of no greater than 250 volts, has a rated storage volume not more than 120 gallons (450 liters), and is designed to transfer thermal energy from one temperature level to a higher temperature level to deliver water at a thermostatically controlled temperature less than or equal to 180 °F (82 °C). 79 FR 40542, 40567 (July 11, 2014).

Then, in the November 2016 Final Rule, DOE reasoned that even though gas-fired heat pump water heaters were covered by the existing test procedure, this definition was extraneous because it is not specifically referenced in any part of DOE's test procedures or energy conservation standards for consumer water heaters. 81 FR 79261, 79261, 79287 (Nov. 10, 2016). The definition for “gas-fired heat pump water heater” was deleted, and the current definition for “gas-fired storage water heater” was added instead.

Id.

at 81 FR 79320-79321.

Since the deletion of the definition in the November 2016 Final Rule, ASHRAE published an updated version of the test standard 118.2, “Method of Testing for Rating Residential Water Heaters and Residential-Duty Commercial Water Heaters,” in January 2022 (ASHRAE 118.2-2022) (

see

section III.B.2 for further discussion of this standard). The January 2022 NOPR issued prior to publication of ASHRAE 118.2-2022 and assessed public review drafts of ASHRAE 118.2-2022—all of which still included a definition for

“gas-fired heat pump storage water heater.” The definition for “gas-fired heat pump storage water heaters” in the public review drafts of ASHRAE 118.2-2022 was adopted in section 2.4 of the final published version, which defines the term as follows:

(a) Use gas as the main energy source,

(b) Have a nameplate input rating of 20,000 Btu/h (26.4 MJ/h) or less,

(c) Have a maximum current rating of 24 amp (including all auxiliary equipment, such as fans, pumps, controls, and, if on the same circuit, any resistive elements) at an input voltage of no greater than 250 V,

(d) Have a rated storage volume not more than 120 gal (450 L), and

(e) Are designed to transfer thermal energy from one temperature level to a higher temperature level to deliver water at a thermostatically controlled temperature less than or equal to 180 °F (82 °C).

In the January 2022 NOPR, DOE stated that, currently, a water heater that uses gas as the main energy source, has a nameplate input rating of 75,000 Btu/h or less, and contains more than one gallon of water per 4,000 Btu per hour of input is a gas-fired storage water heater. (10 CFR 430.2) If the gas-fired storage water heater also has a heat pump with a maximum current rating of 24 amperes at a voltage no greater than 250 volts, is designed to transfer thermal energy from one temperature level to a higher temperature level for the purpose of heating water, including all ancillary equipment such as fans, storage tanks, pumps, or controls necessary for the device to perform its function, it would be a heat pump type unit (see 10 CFR 430.2). 87 FR 1554, 1564 (Jan. 11, 2022).

DOE also noted in the January 2022 NOPR that this industry definition establishes the scope of coverage for these products more narrowly than the current definitions for “gas-fired storage water heater” and “heat pump type” water heater together. Specifically, the ASHRAE 118.2-2022 definition limits the input rate at 20,000 Btu/h—presumably because the input rates of models currently in development for residential applications are less than 20,000 Btu/h—whereas the current definitions at 10 CFR 430.2 accommodate potential future products up to 75,000 Btu/h. In recognition of the developing market for gas-fired heat pump water heaters, DOE had tentatively determined not to limit scope of coverage to only 20,000 Btu/h. 87 FR 1554, 1564 (Jan. 11, 2022).

In response to the January 2022 NOPR, BWC suggested DOE re-evaluate whether current consumer water heater definitions adequately cover gas-fired heat pump water heaters (as defined by ASHRAE) in light of questions as to whether features related to these products depart from the current consumer water heater definitions. (BWC, No. 33 at p. 2) However, the commenter did not provide further details.

DOE did not receive any additional comments elucidating which features may be of concern, and as a result, DOE is not able to identify reasons to justify redefining gas-fired heat pump storage water heaters in a way that departs from the current definitions. At the time of this final rule, such products are still mostly in the field trial stage in the United States, and, thus, they are not mass-produced, nor are they widely distributed in the commercial market. However, DOE is aware that products currently under development consist of a modulating gas-fired burner that powers an absorption cycle using a design which would meet the definition for a “split-system heat pump water heater” (discussed in section III.A.2.a of this document). Nonetheless, because the current definitions for “gas-fired storage water heater” and “heat pump type” water heater are sufficiently broad, such products would remain appropriately encompassed within the current scope of coverage. Should more designs of gas-fired heat pump water heaters (either storage type or instantaneous type) emerge into the water heaters market, DOE would evaluate the definitions and appropriateness of its test methods for gas-fired and heat pump products as they would apply to this novel technology.

Moreover, while ASHRAE 118.2-2022 does define gas-fired heat pump storage water heaters, there are no unique test methods for these products outlined in the industry test standards. Similar to the determination in the November 2016 Final Rule, DOE has concluded that the definition in ASHRAE 118.2-2022 is extraneous. Furthermore, given that no concrete concerns regarding the applicability of the current methods to gas-fired heat pump water heaters have been identified, DOE has determined not to adopt any specific provisions for these in its amended appendix E test procedure at this time.

3. Residential-Duty Commercial Water Heaters

In this rulemaking, DOE has sought comment on the definition for “residential-duty commercial water heater,” which defines a category of commercial water heaters that are subject to the appendix E test procedure due to their residential applications. 85 FR 21104, 21108 (April 16, 2020).

In the January 2022 NOPR, DOE acknowledged that some water heaters intended for commercial use are covered by the residential-duty commercial water heater definition and tested and rated to the appendix E test procedure and residential-duty commercial water heater energy conservation standards in terms of UEF. DOE explained that these water heaters have characteristics that are similar to water heaters with residential applications and, as such, under 42 U.S.C. 6295(e)(5)(F), cannot be excluded from being tested and rated using the consumer water heaters test procedure and residential-duty commercial water heater energy conservation standards. Thus, DOE did not propose amendments to this definition. 87 FR 1554, 1566 (Jan. 11, 2022).

DOE has determined that whether a product is marketed as commercial or residential may not always be indicative of the intended installation location. The January 2022 NOPR provided the example of water heaters that are intended for residential use but sometimes marketed as “commercial-grade” as a means to convey an expectation of reliability. 87 FR 1554, 1566-1567 (Jan. 11, 2022).

In commenting on the January 2022 NOPR, with regards to residential-duty commercial water heaters, AET commented that the method used to evaluate consumer electric instantaneous and residential-duty commercial electric instantaneous water heaters in the December 2016 Conversion Factor Final Rule was not approved for these products, and the energy conservation standards DOE issued for consumer water heaters could not be met by them. AET argued that the energy conservation standards for residential-duty commercial electric instantaneous water heaters were based on performance for fossil fuel-fired commercial tankless water heaters as opposed to actual product testing, and, therefore, the commenter asserted that the minimum efficiency requirements for residential-duty commercial electric instantaneous water heaters are too low and should be updated. (AET, No. 29 at pp. 14-15)

DOE understands that the commenter's discussion of the “method used to evaluate consumer electric instantaneous and residential-duty commercial electric instantaneous water heaters” refers to the analytical approach in 2016 that was used to predict the UEF values of these water heaters from existing representations of maximum GPM (

see

81 FR 96204,

92616-92617 (Dec. 29, 2016)) and thermal efficiency (

see

81 FR 96204, 96218 (Dec. 29, 2016)). At this time, however, the current appendix E test procedure does provide a method to test and rate these water heaters.

DOE notes that there are currently consumer and residential-duty commercial electric instantaneous water heaters certified to meet the applicable energy conservation standards.

Section 5.3.2 of appendix E details the Max GPM rating test for flow-activated water heaters, Table II in section 5.4.1 of appendix E details how to select draw pattern based on Max GPM rating, and sections 5.4.2 and 5.4.3 of appendix E detail the test sequence.

Otherwise, DOE did not receive any comments specifically pertaining to the definition for residential-duty commercial water heaters. Therefore, DOE is not amending the definition for “residential-duty commercial water heater” in this final rule for the reasons previously discussed. DOE may consider potential amended standards for residential-duty commercial electric instantaneous water heaters in a separate rulemaking addressing the energy conservation standards for commercial water heaters.

DOE is concurrently evaluating energy conservation standards for commercial water heaters in Docket No. EERE-2021-BT-STD-0027.

4. Specialty Water Heaters

As first proposed in the January 2022 NOPR, this final rule expands the scope of coverage of the appendix E test procedure to include low-temperature water heaters and circulating water heaters, which both fall under the statutory definition of consumer “water heater” but did not previously have test methods appropriate for their unique operation. DOE is also re-instating an inadvertently omitted definition for “tabletop water heater” at 10 CFR 430.2. In addition, DOE has considered whether to address solar water heaters in the consumer water heaters test procedure, but the Department has determined not to expand the scope of coverage of the appendix E to these products at this time. DOE may further consider solar water heaters in a separate rulemaking in the future. Each of these categories of water heaters is discussed in the following subsections.

Dyson generally commented that indirect circulation systems especially have an extraordinarily flexible use case and can be implemented in both warm and cool regions. (Dyson, No. 28 at p. 1) DOE understands this comment to refer to systems which use a separate boiler to provide the heat source for domestic water heating. However, consumer boilers are not within the scope of this rulemaking.

a. Circulating Water Heaters

As discussed in section III.A of this document, a gas-fired instantaneous water heater is a water heater that uses gas as the main energy source, has a nameplate input rating less than 200,000 Btu per hour, and contains no more than one gallon of water per 4,000 Btu per hour of input. 10 CFR 430.2.

In the April 2020 RFI, DOE requested feedback on the typical application of a specific configuration of gas-fired instantaneous water heaters, commonly referred to as “circulating gas-fired instantaneous water heaters.” 85 FR 21104, 21113 (April 16, 2020). As explained in the April 2020 RFI, DOE has found that several manufacturers produce consumer gas-fired instantaneous water heaters that are designed to be used with a volume of stored water (usually in a tank, but sometimes in a recirculating hot water system of sufficient volume, such as a hydronic space heating or designated hot water system) in which the water heater does not provide hot water directly to fixtures, such as a faucet or shower head, but rather replenishes heat lost from the tank or system through hot water draws or standby losses by circulating water to and from the tank or other system. These circulating gas-fired instantaneous water heaters are typically activated by an aquastat

installed in a storage tank that is sold separately or by an inlet water temperature sensor. DOE further stated that while the products identified by DOE are within the statutory and regulatory definition of a consumer “water heater” and, therefore, a covered product, the design and application of circulating gas-fired instantaneous water heaters make testing to the currently applicable Federal test procedure for consumer water heaters difficult, if not impossible, as these products are not capable of delivering water at the temperatures and flow rates specified in the UEF test method contained therein.

Id.

As a result, the currently applicable appendix E test procedure does not sufficiently cover circulating water heaters.

An “aquastat” is a temperature measuring device typically used to control the water temperature in a separate hot water storage tank.

DOE received several comments on the April 2020 RFI recommending generally that DOE amend the regulatory definitions of gas-fired instantaneous water heaters to exclude models designed exclusively for commercial use even though they have input rates below the consumer water heater input rate limit (

i.e.,

≤200,000 Btu/h). AHRI and individual manufacturers commented that these products are used in commercial applications even though they may in certain cases meet the statutory definition for a consumer water heater, and that the residential draw pattern profiles may not be applicable. These comments are discussed in detail in the January 2022 NOPR. 87 FR 1554, 1565 (Jan. 11, 2022).

In the January 2022 NOPR, DOE noted that 42 U.S.C. 6291(1) states that a “consumer product” means any article of a type which, to any significant extent, is distributed in commerce for personal use or consumption by individuals. DOE also stated that its examination of product literature has found that circulating water heaters are predominately marketed for commercial applications. However, the input rates of many of the available models are below the maximum input rate of a consumer water heater and can, therefore, be suitable for residential applications. DOE noted that there exist circulating heat pump water heaters (heat pump-only water heaters) which operate in the same manner as gas-fired circulating water heaters but are clearly marketed for residential applications. Consequently, it is foreseeable that there could be the potential for product substitution into the consumer market. For these reasons, DOE tentatively determined that circulating water heaters are covered “consumer products.” 87 FR 1554, 1565 (Jan. 11, 2022).

In the January 2022 NOPR, DOE proposed to include the following definition at 10 CFR 430.2: “

Circulating water heater

means an instantaneous or heat pump-type water heater that does not have an operational scheme in which the burner, heating element, or compressor initiates and/or terminates heating based on sensing flow; has a water temperature sensor located at the inlet of the water heater or in a separate storage tank that is the primary means of initiating and terminating heating; and must be used in combination with a recirculating pump and either a separate storage tank or water circulation loop in order to achieve the water flow and temperature conditions recommended in the manufacturer's installation and operation instructions.” 87 FR 1554, 1565 (Jan. 11, 2022).

Commenters had varying viewpoints on this topic. AET expressed general agreement with DOE's proposal to add a new definition and product category for circulating water heaters. (AET, No. 29 at p. 1)

Rheem supported the addition of a definition for “circulating water heater” to 10 CFR 430.2 and accompanying test procedures within appendix E for such products that have residential applications, but the commenter emphasized that the division between consumer and commercial water heaters should be appropriately set. Rheem argued that because a “circulating water heater” must use a separate storage tank, circulating water heater product classes should be defined using the storage-type unit input rate criteria (

e.g.,

a gas-fired circulating water heater with an input rate at or below 75,000 Btu/h is a consumer water heater and greater than 75,000 Btu/h is a commercial water heater). Rheem also recommended further investigation as to whether certain capacities of storage-type water heaters could be covered by the “circulating water heater” definition. Rheem added that the “circulating water heater” definition should be amended to allow a water temperature sensor at the outlet of the water heater. (Rheem, No. 31 at p. 2)

BWC generally disagreed with DOE's proposal that circulating water heaters should be covered as consumer products, arguing that these products are exclusively installed in commercial applications as either part of a recirculation loop or coupled to an unfired hot water storage tank. BWC also noted that circulating water heaters heat water to higher temperatures than consumer instantaneous water heaters do. BWC argued that classifying circulating water heaters as consumer products would provide little to no benefit to consumers, place additional burden on manufacturers, and cause market confusion as to how these products are specified and designed for field applications. (BWC, No. 33 at pp. 1-2)

AHRI expressed concerns about including circulating water heaters in a residential water heaters test procedure because they are mostly used in commercial applications, even with input rates below 200,000 Btu/h. In lieu of a solution in the test procedure, AHRI requested that DOE reinstate the enforcement policy on circulating water heaters.

(AHRI, No. 40 at p. 5) A.O. Smith provided similar comments, suggesting that DOE should reissue the September 5, 2019 enforcement policy for gas-fired circulating water heaters, or alternatively identify them in the test procedure as “historically regulated as commercial water heating equipment” that “can be tested via the thermal efficiency energy metrics; and . . . therefore should not be subjected to UEF requirements.” (A.O. Smith, No. 37 at pp. 2-3) Like AHRI and A.O. Smith, BWC recommended reinstating the September 2019 enforcement policy to allow industry to determine the proper test procedure. (BWC, No. 33 at pp. 1-2)

DOE had issued an enforcement policy for circulating water heaters that expired on December 31, 2021.

EEI requested more information on the size of the existing stock and current sales volumes of circulating water heaters. (EEI, Jan. 27, 2022 Public Meeting Transcript, No. 27 at pp. 46-47)

In response, the Department reiterates that EPCA directed DOE to develop a test procedure that applies, to the maximum extent practicable, to all water heating technologies in use and to future water heating technologies. (42 U.S.C. 6295(e)(5)(H)) As a circulating water heater could be designed to operate in a similar manner to other consumer water heaters (

i.e.,

“heat pump-only” water heaters) and at conditions appropriate for residential applications, DOE is required to address these products in appendix E with other classes of consumer water heaters. Furthermore, the definition for “consumer product” states that it is an article “of a type” that is distributed for personal use or consumption by individuals “without regard to whether such article of such type is in fact distributed in commerce for personal use or consumption by an individual.” (42 U.S.C. 6291(1))

In response to Rheem's comment, circulating water heaters have high input rate to storage volume ratios, which classify these products as instantaneous-type water heaters (

see

10 CFR 430.2 and 42 U.S.C. 6291(27)(B)). As such, the statutory definition of a storage-type water heater (found at 42 U.S.C. 6291(27)(A)) does not cover circulating water heaters because circulating water heaters have no more than one gallon of water per 4,000 Btu/h of input. As a result, the 75,000 Btu/h upper limit on the input rate for gas-fired storage-type water heaters would not apply and will not be included in the scope of the definition of “circulating water heater.”

In response to BWC's comments, DOE notes that hot water delivery temperature is not related to the statutory definition of coverage. Rather, EPCA defines whether a water heater is covered as a consumer product primarily according to its input rating, without regard to its maximum hot water delivery temperature. DOE also concludes that classifying circulating water heaters (that meet the input rating requirements) as consumer products would provide a benefit to consumers by allowing them to compare circulating water heaters alongside other consumer water heaters with a UEF rating. Under 42 U.S.C. 6293(b), EPCA requires that DOE test procedure not place undue burden on manufacturers. In this instance, although test burden would increase for manufacturers of circulating water heaters, it would not be considered an undue burden, because these water heaters are consumer products (by definition) and, therefore, should be subject to consumer water heater test procedures. Contrary to BWC's assertion, DOE concludes that covering circulating water heaters as consumer products would reduce or resolve market confusion surrounding these products; since they can be used in residential applications, they should be rated accordingly.

In response to A.O. Smith's comment requesting DOE to consider circulating gas-fired water heaters as historically regulated as commercial water heaters and sufficiently described by the commercial water heater metrics, DOE is not expanding the scope to products which are “historically regulated as commercial water heating equipment” because DOE is only considering circulating gas-fired water heaters with input rates less than or equal to 200,000 Btu/h, which meet the existing statutory definition for consumer water heaters (and, thus, do not meet the definition for gas-fired instantaneous commercial water heaters). Furthermore, DOE clarifies that the Department is not considering these gas-fired circulating water heaters (ones which meet the existing statutory definition for consumer water heaters) to be residential-duty commercial water heaters.

In response to the July 2022 SNOPR, BWC and AHRI once again reiterated their understanding that circulating water waters are used almost exclusively in commercial applications. (BWC, No. 48 at p.4; AHRI, No. 55 at p. 5) BWC requested that DOE exercise authority granted under the American Manufacturing Technical Corrections Act (AEMTCA) (42 U.S.C. 6295(e)(5)(F)) to regulate circulating water heaters as commercial products even though they meet residential definitions, or clearly demonstrate residential use. (BWC, No. 48 at p. 4) AHRI suggested that addressing circulating water heaters in a consumer rulemaking would cause confusion because their efficiency metric is different from conventional consumer water heaters. (AHRI, No. 55 at p. 5)

In response, EPCA allows DOE to provide an exclusion from the uniform

efficiency descriptor for specific categories of otherwise 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)(i))

However, DOE reads this statutory provision as only permitting exclusion of water heaters that were categories of covered

commercial

water heaters under section 342(a)(5) of EPCA [42 U.S.C. 6313(a)(5)]. It does not grant DOE authority to exclude consumer water heaters from the ambit of the uniform test procedure, nor to somehow convert consumer water heaters to commercial water heaters and to subject them to energy conservation standards applicable to commercial water heaters. In the present case, it is clear that the circulating water heaters in question are consumer water heaters, given that they have input rates below 200,000 Btu/h, and they otherwise meet the definitional criteria of the statute for an instantaneous-type water heater (

see

42 U.S.C. 6291(27)(B)). Moreover, circulating water heaters have the demonstrated ability to perform tank loading or recirculating loop operation, as would indicate that these products do have clearly described residential uses. Consequently, in response to these comments, DOE notes that because both heat pump-only and gas-fired circulating water heaters meet the requirements to be classified as consumer products under EPCA, the statute requires that such water heaters must be tested according to DOE test procedure at appendix E.

DOE acted in accordance with EPCA provisions as specified at 6295(e)(5)(F)(i) when establishing product classes for residential-duty commercial water heaters. In a July 2014 Final Rule establishing the UEF test procedure, DOE determined that covered commercial water heating equipment that did not meet the definition of a “residential-duty commercial water heater” met the criteria in EPCA for exclusion from the uniform efficiency descriptor. 79 FR 40542, 40545-40547 (July 11, 2014).

This final rule establishes a test method to determine the UEF of consumer circulating water heaters. Effective and compliance dates are discussed further in section III.I of this document.

In development of this final rule, DOE was not able to discern rates of shipments and amount of stock for consumer circulating water heaters as EEI had requested. However, DOE did identify circulating water heater models currently on the market that are consumer water heaters. DOE has determined that circulating water heaters may have a water temperature sensor at the inlet or at the outlet of the water heater—as suggested by Rheem— and, therefore, the Department agrees with Rheem and is adopting the following definition for “circulating water heater” at 10 CFR 430.2:

Circulating water heater

means an instantaneous or heat pump-type water heater that does not have an operational scheme in which the burner, heating element, or compressor initiates and/or terminates heating based on sensing flow; has a water temperature sensor located at the inlet or at the outlet of the water heater or in a separate storage tank that is the primary means of initiating and terminating heating; and must be used in combination with a recirculating pump and either a separate storage tank or water circulation loop in order to achieve the water flow and temperature conditions recommended in the manufacturer's installation and operation instructions.

b. Low-Temperature Water Heaters

DOE has identified certain flow-activated water heaters that are designed to deliver water at temperatures below the set point temperature of 125 °F ±5 °F (51.7 °C ±2.8 °C) that is required by section 2.5 of the currently applicable appendix E (hereinafter referred to as “low-temperature” water heaters). These low-temperature water heaters (often referred to as “handwashing” or “point-of-use” water heaters in marketing literature) typically have low heating rates, which requires the testing agency to reduce the flow rate in order to be able to achieve the outlet temperature within the set point temperature range. However, these units also have a minimum activation flow rate below which the unit shuts off. To the extent that a unit would stop heating water when the flow rate is too low, there may be no flow rate at which the unit would operate and deliver water at the outlet temperature required under section 2.5 of appendix E. Further, the definition of water heater or electric instantaneous water heater does not include a minimum water delivery temperature. To the extent that a low-temperature water heater uses electricity as the energy source, has a nameplate input rating of 12 kilowatts or less, and contains no more than one gallon of water per 4,000 Btu per hour of input, it would be an electric instantaneous water heater. 10 CFR 430.2. Therefore, because such products are within the scope of consumer water heater coverage under EPCA, the appendix E test procedure should address them; however, the currently applicable appendix E does not address them.

DOE requested information in the April 2020 RFI on testing these products at a lower set point temperature and other potential changes which may be necessary to accommodate these types of models. 85 FR 21104, 21113 (April 16, 2020). Several commenters on the April 2020 RFI recommended that the test procedure be modified to indicate a lower set point temperature for testing, such as the maximum water temperature delivery that the model is capable of delivering (see NOPR discussion for complete details). 87 FR 1554, 1582 (Jan. 11, 2022).

In the January 2022 NOPR, DOE proposed to define a “low-temperature water heater” as an electric instantaneous water heater that is not a circulating water heater and cannot deliver water at a temperature greater than or equal to the set point temperature specified in section 2.5 of appendix E to subpart B of this part when supplied with water at the supply water temperature specified in section 2.3 of appendix E to subpart B of this part. DOE also tentatively determined that lowering the set point temperature for low-temperature water heaters to their maximum possible delivery temperature would allow these water heaters to be tested appropriately and in a representative manner. As such, DOE proposed to require low-temperature water heaters to be tested to their maximum possible delivery temperature. 87 FR 1554, 1583 (Jan. 11, 2022).

AET agreed with DOE's proposal to add a new definition and product category for low-temperature water heaters. (AET, No. 29 at p. 2) EEI requested more information on the size of the existing stock, as well as the current sales volumes of low-temperature water heaters. (EEI, Jan, 27, 2022 Public Meeting Transcript, No. 27 at pp. 46-47) As with circulating water heaters, DOE does not currently have this information available but will continue to gather this data to the extent possible.

Rheem commented that the proposed definition for “low-temperature water heater” should include water heaters with less than 10 gallons of storage and clarify how it is different from other electric water heaters. Rheem suggested that the installation and operation (I&O) manual could be referenced to determine delivery temperature limits, but alternatively, manufacturers could certify supplemental testing instructions to DOE (

i.e.,

when testing an electric instantaneous water heater set according to the I&O manual and cannot meet the required delivery temperature, the unit should be tested according to the

maximum delivery temperature). (Rheem, No. 31 at p. 3)

In response to the comments from Rheem, DOE notes that the inability to deliver water at the specified outlet water temperatures in appendix E is independent of the storage volume of the water heater. Hence, restricting this product type definition to only those water heaters that have less than 10 gallons of storage volume may unintentionally leave larger low-temperature water heaters without adequate test provisions in appendix E. This inability to deliver water at 125 °F ±5 °F—

specifically at the appendix E flow rate

—serves as the key distinguishing factor between low-temperature water heaters and other electric instantaneous water heaters. While the maximum delivery temperatures may be noted in an I&O manual, as Rheem suggested, this must be verified under the test conditions (most notably the supply water temperatures) specified in appendix E. Section 5.2.2 of the amended appendix E includes instructions for setting the outlet discharge temperature. Should the flow rate need to be reduced in order to meet the outlet temperature requirements, then the product would meet the criterion for a low-temperature water heater.

In this final rule, DOE is adopting a slightly modified definition for “low-temperature water heater,” taking into account the comments provided by Rheem. Accordingly, DOE is defining “low-temperature water heater” as an electric instantaneous water heater that is not a circulating water heater and cannot deliver water at a temperature greater than or equal to the set point temperature specified in section 2.5 of appendix E when supplied with water at the supply water temperature specified in section 2.3 of appendix E at the flow rate specified in section 5.2.2.1 of appendix E. (DOE is including language which specifies that the delivery temperature is that which results from the appendix E flow rate.)

c. Tabletop Water Heaters

As discussed in the January 2022 NOPR, the definition for “tabletop water heater” was removed from appendix E as part of the July 2014 Final Rule but was inadvertently not added to 10 CFR 430.2 (79 FR 40542, 40567-40568 (July 14, 2014)). 87 FR 1554, 1566 (Jan. 11, 2022). Up until then, “tabletop water heater” was defined as a water heater in a rectangular box enclosure designed to slide into a kitchen countertop space with typical dimensions of 36 inches high, 25 inches deep, and 24 inches wide. 66 FR 4474, 4497 (Jan. 17, 2001). In the January 2022 NOPR, after considering comments on the April 2020 RFI, DOE proposed to add the definition of tabletop water heater 10 CFR 430.2, as it read prior to being removed from appendix E. 87 FR 1554, 1556.

In response to the January 2022 NOPR, AET agreed with re-instating the definition for tabletop water heater at 10 CFR 430.2. (AET, No. 29 at p. 2)

DOE did not receive any other comment relating to this proposal, so the Department is re-instating the definition for “tabletop water heater” at 10 CFR 430.2, as proposed.

d. Solar Water Heaters

In response to an RFI published on May 21, 2020 (May 2020 RFI), regarding the energy conservation standards for consumer water heaters (85 FR 30853), the Solar Rating & Certification Corporation (SRCC) recommended that solar water heating technologies be considered for inclusion in the energy conservation standards and test procedures for consumer water heaters. SRCC stated that without the involvement of DOE, the industry metrics struggle to gain acceptance with policymakers and consumers. SRCC also stated that DOE rulemakings to include solar-equipped water heaters in regulations would serve to establish a single performance metric and signal the legitimacy of solar water heating technologies. (Docket: EERE-2017-BT-STD-0019, SRCC, No. 11 at pp. 3-4)

Subsequently, on October 7, 2020, SRCC published a draft test procedure titled, “Solar Uniform Energy Factor Procedure for Solar Water Heating Systems” (SUEF test method).

The draft SRCC test procedure addresses methods to test different types of solar water heaters.

SRCC's draft Solar Uniform Energy Factor Procedure for Solar Water Heating Systems is available at:

www.iccsafe.org/wp-content/uploads/is_stsc/Solar-UEF-Specification-for-Rating-Solar-Water-Heating-Systems-20201012.pdf

(Last accessed on July 13, 2022).

In the January 2022 NOPR, DOE responded to SRCC's comment on the May 2020 RFI, by noting that on April 8, 2015, DOE published an energy conservation standards NOPR (the April 2015 NOPR) addressing definitions for consumer water heaters (80 FR 18784). 87 FR 1554, 1585 (Jan. 11, 2022). DOE further noted that the April 2015 NOPR proposed definitions for “solar-assisted fossil fuel storage water heater” and “solar-assisted electric storage water heater” and clarified that water heaters meeting these definitions are not subject to the amended energy conservation standards for consumer water heaters established by the April 2010 final rule.

Id.

DOE stated its intention to address solar water heaters in a separate rulemaking.

Id.

In response to the January 2022 NOPR, SEA commented that DOE should account for solar water heaters in its test procedure and energy conservation standards. (SEA, No. 24 at p. 1)

In response, DOE notes that “solar water heater,” as defined in section 5.1 of SRCC's SUEF test method, include a solar collector or module that is directly exposed to solar radiation outdoors and is often separated from a storage tank and/or back-up water heater located indoors. Therefore, appendix E does not currently accommodate these products, and an in-depth evaluation of the modifications to appendix E necessary to accommodate the testing of these products is required. Given the lack of available test data utilizing the SUEF test method, DOE is not amending the scope of the appendix E test procedure in this rulemaking to explicitly include solar water heaters at this time. However, DOE will continue to consider these solar water heater products further, and depending upon the conclusions reached, the Department may address them in a separate future rulemaking, as appropriate.

B. Updates to Industry Standards

Prior to the effective date of this final rule, the applicable DOE test procedure in appendix E referenced the following industry standards:

• ASHRAE 41.1-1986 (Reaffirmed 2006), Standard Method for Temperature Measurement (ASHRAE 41.1-1986 (RA 2006)); and

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

ASHRAE 41.1-1986 (RA 2006) was superseded by ASHRAE 41.1-2013 on January 30, 2013 (ASHRAE 41.1-2013). ASHRAE 41.1-2013 was superseded by ASHRAE 41.1-2020 on June 30, 2020. Updates to ASHRAE 41.1 are discussed in section III.B.1 of this document.

ASTM D2156-09 was reapproved without modification in 2018 (ASTM D2156-09 (RA 2018)). In the January 2022 NOPR, DOE proposed to update appendix E to reference the most recent version of ASTM D2156 (

i.e.,

ASTM D2156-09 (RA 2018)). 87 FR 1554, 1567 (Jan. 11, 2022). DOE did not receive any comments in response to its proposal. Therefore, DOE is updating the reference of ASTM D2156-09 to the most recent industry standard (

i.e.,

ASTM D2156-09 (RA 2018)). DOE is also incorporating by reference ASTM E97-1987 (W1991) because it is

necessary to perform procedures within ASTM D2156-09 and ASTM D2156-09 (RA 2018).

Certain methods provided as part of ASTM E97-1987 (W1991) are directly referenced by ASTM D2156-09 and ASTM D2156-09 (RA 2018). Copies of ASTM E97-1987 (W1991) are readily available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959 or online at:

www.astm.org.

(Last accessed on Sept. 20, 2022.)

As discussed previously in this document, ASHRAE maintains a water heater test procedure, ANSI/ASHRAE Standard 118.2, “Method of Testing for Rating Residential Water Heaters.” The test procedure specified in ANSI/ASHRAE 118.2-2006 (RA 2015) is similar to the DOE test procedure that was in effect prior to the July 2014 final rule, although neither the previous DOE consumer water heater test procedure nor the version in place prior to this final rule reference ANSI/ASHRAE Standard 118.2-2006 (RA 2015). In March 2019, ASHRAE published the March 2019 ASHRAE Draft 118.2, the second public review draft of Board of Standards Review (BSR) ANSI/ASHRAE Standard 118.2-2006R, “Method of Testing for Rating Residential Water Heaters and Residential-Duty Commercial Water Heaters,” which DOE referenced in the April 2020 RFI. 85 FR 21104, 21109-21111 (April 16, 2020). In April 2021, ASHRAE published substantive changes to a previous public review draft

of BSR ANSI/ASHRAE Standard 118.2-2006R, “Method of Testing for Rating Residential Water Heaters and Residential-Duty Commercial Water Heaters” (April 2021 ASHRAE Draft 118.2). The January 2022 NOPR examined these public review drafts and discussed the differences between them and the DOE test procedure. 87 FR 1554, 1567 (Jan. 11, 2022).

The April 2021 ASHRAE Draft 118.2 shows only the proposed substantive changes to the March 2019 ASHRAE Draft 118.2. All sections not included in the April 2021 ASHRAE Draft 118.2 are as proposed in the March 2019 ASHRAE Draft 118.2 or have not been changed in a way that their content affects the results of the test procedure proposed in the March 2019 ASHRAE Draft 118.2.

On January 24, 2022, ASHRAE published a revised edition of the 118.2 standard, “Method of Testing for Rating Residential Water Heaters and Residential-Duty Commercial Water Heaters,” ASHRAE 118.2-2022. The published edition finalized revisions shown in the March 2019 and April 2021 public review drafts.

In comments responding to the January 2022 NOPR, Lutz encouraged DOE to incorporate by reference the industry test standard ASHRAE 118.2-2022. Lutz also recommended DOE review the test procedures in use in Europe and Japan. (Lutz, No. 35 at p. 1) BWC supported DOE's proposal to incorporate by reference the latest industry test standards. (BWC, No. 33 at p. 2)

As discussed previously in this document, DOE will adopt industry test standards as DOE test procedures for covered products and equipment, unless such methodology would be unduly burdensome to conduct or would not produce test results that reflect the energy efficiency, energy use, water use (as specified in EPCA) or estimated operating costs of that equipment during a representative average use cycle. (10 CFR part 430, subpart C, appendix A, section 8(c)) In this final rule, DOE is harmonizing provisions in appendix E to align with certain updates in ASHRAE 118.2-2022 rather than incorporate the entire industry test standard. DOE has concluded that certain updates in ASHRAE 118.2-2022 do not meet the EPCA criteria outlined in this paragraph and has, thus, determined that those updates should not be incorporated into the DOE test procedure at appendix E. DOE's assessment of ASHRAE 118.2-2022 is laid out in detail in section III.B.2 of this document.

Finally, as discussed in the July 2022 SNOPR, DOE has reviewed NEEA's Advanced Water Heating Specifications in order to assess optional rating conditions and methods for heat pump water heaters. This test procedure was identified by stakeholders in response to the January 2022 NOPR as becoming a widely used methodology to provide alternate ratings for heat pump water heaters at different climate conditions. 87 FR 42270, 42275-42276 (July 14, 2022). In the January 2022 NOPR, DOE discussed comments previously received on the April 2020 RFI suggesting that DOE explore the usage of NEEA's Advanced Water Heating Specification—which was at version 7.0 at the time—for voluntary climate-specific efficiency representations of heat pump water heaters. 87 FR 1554, 1580 (Jan. 11, 2022). In response to those comments, DOE stated that it did not have data to indicate what conditions would be representative for regional representations, and, thus, DOE tentatively determined not to allow optional representations of additional efficiency ratings at test conditions other than those found in the DOE test procedure (which are representative of the Nation as a whole), such as those made in accordance with NEEA's Advanced Water Heating Specification.

Id.

However, as discussed in the July 2022 SNOPR, DOE has re-evaluated the benefits to consumers provided by optional representations. 87 FR 42270, 42275-42277 (July 14, 2022). In this final rule, DOE is including optional test conditions for heat pump water heaters aligning with version 8.0 (the latest version) of NEEA's Advanced Water Heating Specification. This matter is discussed in further detail in section III.C.7 of this document.

1. ASHRAE 41.1-2020

As stated previously, ASHRAE 41.1-1986 (RA 2006) was superseded by ASHRAE 41.1-2013, and ASHRAE 41.1-2013 was superseded by ASHRAE 41.1-2020. ASHRAE 41.1-2013 removed the aspirated wet-bulb psychrometer descriptions and stated they would be included in the next revision to ASHRAE 41.6, “Standard Method for Humidity Measurement.” ASHRAE 41.6 was updated on July 3, 2014, and included the aspirated wet-bulb psychrometer descriptions that were removed in ASHRAE 41.1-2013. ASHRAE 41.1-2013 also added uncertainty analysis for temperature measurements, information for thermistor-type devices, descriptions for thermopiles, and reorganized the standard to be consistent with other ASHRAE standards. ASHRAE 41.1-2020 added conditional steady-state test criteria and further updated the standard to meet ASHRAE's mandatory language requirements.

As discussed in the January 2022 NOPR, section 3.2.1 of appendix E requires that temperature measurements be made in accordance with ASHRAE 41.1-1986 (RA 2006), and section 3.2.2 of appendix E provides accuracy and precision requirements for air dry-bulb, air wet-bulb, inlet and outlet water, and storage tank temperatures. Sections 5.2.2.1 and 5.3.2 of appendix E effectively require steady-state operation in which the flow-activated water heater is operating at the maximum input rate, is supplied with water at a temperature of 58 °F ±2 °F, and delivers water at a temperature of 125 °F ±5 °F. 87 FR 1554, 1567 (Jan. 11, 2022).

In the development of this final rule, DOE reviewed ASHRAE 41.1-1986 (RA 22006), ASHRAE 41.1-2013, and ASHRAE 41.1-2020 and found that the sections most relevant to appendix E are the temperature measurement sections (

i.e.,

sections 5 through 11 of ASHRAE 41.1-1986 (RA 2006), section 7 of ASHRAE 41.1-2013, and section 7 of ASHRAE 41.1-2020)

and the steady-state test criteria added in ASHRAE 41.1-2020. The information in the

temperature measurement sections of the examined three versions of ASHRAE 41.1 does not vary significantly. The additional steady-state test criteria of ASHRAE 41.1-2020 varies significantly from and is more stringent than

the criteria specified in sections 5.2.2.1 and 5.3.2 of appendix E; however, the appendix E criteria supersede those in ASHRAE 41.1-2020.

Sections 5 through 11 of ASHRAE 41.1-1986 (RA 2006) were combined into section 7 of ASHRAE 41.1-2013.

Section 5.5.3 of ASHRAE 41.1-2020 would be used to determine steady-state operation within sections 5.2.2.1 and 5.3.2 of appendix E. Using this criteria, a flow-activated water heater delivering water between 120 °F and 121 °F, which is within the current delivery temperature range of 125 °F ± 5 °F, would not be considered in steady-state due to the difference in temperature between the average of the sample and the set point temperature.

In the January 2022 NOPR, DOE tentatively determined that updating the reference of ASHRAE 41.1-1986 (RA 2006) to the most recent version of the industry standard (

i.e.,

ASHRAE 41.1-2020) would not have a significant effect on the test results, as the content of the relevant sections of the ASHRAE 41.1 standards have not changed significantly and the new content published in ASHRAE 41.1-2020 is superseded by appendix E. As such, DOE proposed to update the reference of ASHRAE 41.1-1986 (RA 2006) to ASHRAE 41.1-2020. ASHRAE 41.1-2020 references ASHRAE 41.6-2014 and requires its use when measuring the wet-bulb temperature. The wet-bulb temperature is required when testing heat pump water heaters to appendix E, and, therefore, DOE also proposed to incorporate by reference ASHRAE 41.6-2014. 87 FR 1554, 1567-1568 (Jan. 11, 2022).

DOE did not receive any comments in response to its proposals to incorporate by reference ASHRAE 41.1.-2020 and ASHRAE 41.6-2014; therefore, DOE is incorporating by reference both standards in this final rule for the reasons previously stated.

2. ASHRAE 118.2-2022

ASHRAE 118.2-2022, published on January 24, 2022 and approved by ANSI on March 1, 2022, supersedes ASHRAE 118.2-2006. The foreword to ASHRAE 118.2-2022 states that it was derived from the DOE appendix E test procedure but also has several substantive changes. Specifically, it notes that a major change was to move the conditions of the test (air temperature, humidity, inlet and outlet water temperatures) and draw patterns to an Informative Appendix A, “U.S. Values for Test Variables,” indicating that this test standard has been revised such that it can easily be applied with other test conditions and draw patterns. Additionally, the foreword states that other changes include clarifying the timing of the standby period, clarifying the end of the recovery period, specifying that the density of water used in calculations be measured at the outlet, and adjusting the FHR flow rate for smaller tanks and defining a draw time limit if the water heater can keep up with the FHR flow rate. The following subsections of this final rule discuss the substantial differences between the updated ASHRAE 118.2-2022 test standard and DOE's existing appendix E test procedure. Based on a review of its own test data and stakeholder feedback, the Department is not adopting every update in ASHRAE 118.2-2022 into the amended appendix E test procedure promulgated by this final rule. DOE has provided discussion of the amendments being made to harmonize with ASHRAE 118.2-2022 in section III.B.2.b of this document, whereas other updates in ASHRAE 118.2-2022 not being adopted are discussed in section III.B.2.c of this document.

AET generally supported DOE's proposal to adopt most aspects of ASHRAE 118.2 but noted that the definition of “UEF” in ASHRAE 118.2 is different from the definition of that term used by DOE. AET noted that a UEF rating per ASHRAE Standard 118.2 would not be comparable to a UEF rating per DOE's test procedure due to differences in test conditions. (AET, No. 29 at pp. 6-7) DOE agrees that there could be differences between the UEF test result from ASHRAE 118.2-2022 and the amended appendix E test procedure from this final rule. Where differences between these test procedures exist, the requirements at 10 CFR 430.23 and appendix E control. As such, manufacturers must ensure that any representations of “UEF” are made in accordance with the applicable version of the DOE test procedure.

a. Scope

Section 2 of ASHRAE 118.2-2022 states that the industry test standard applies to water heaters designed to be capable of providing outlet water at a controlled temperature of at least the nominal outlet water temperature under the conditions specified in the standard. As discussed in section III.A.4.b of this final rule, the January 2022 NOPR proposed to expand the scope of the DOE test procedure to include low-temperature water heaters. 87 FR 1554, 1582-1583 (Jan. 11, 2022). As such, the scope of ASHRAE 118.2-2022 is narrower than the test procedure proposed in DOE's January 2022 NOPR and July 2022 SNOPR because it explicitly excludes low-temperature water heaters. In order to include low-temperature water heaters within the scope of the amended appendix E test procedure, DOE is including testing provisions which are not in ASHRAE 118.2-2022 to allow for the testing of low-temperature water heaters. These test methods are discussed in section III.E.3 of this final rule.

Additionally, the scope of ASHRAE 118.2-2022 differs significantly from the scope of products covered under the EPCA definition for consumer “water heater” and DOE's definition for “residential-duty commercial water heater.” For example, section 2 of ASHRAE 118.2-2022 limits the storage volume for storage-type water heaters to 120 gallons or less and limits the maximum delivery temperature to 180 °F (82 °C), whereas EPCA does not place limits on storage volume or maximum delivery temperature for consumer water heaters. (42 U.S.C. 6291(27); 42 U.S.C. 6311(12)(A)-(B))) The scope of electric instantaneous water heaters covered by ASHRAE 118.2-2022 equates to the limit for residential-duty commercial electric instantaneous water heaters; however, section 2.2 of ASHRAE 118.2-2022 does not specify any limits on storage volume, and as a result, it covers certain commercial electric instantaneous water heaters—whereas the currently applicable appendix E test procedure does not. Section 2.1 of ASHRAE 118.2-2022 has a definition for “electric heat-pump storage water heater” which explicitly limits the nameplate input rating to 12 kilowatts or less, which, as discussed in section III.A.2.a of this final rule, does not correspond to the statutory limit for heat pump-type units and would include commercial heat pump water heaters (which are outside of the scope of the appendix E test procedure). Finally, section 2.4 of ASHRAE 118.2-2022 limits gas-fired heat pump storage water heaters to nameplate input ratings no greater than 20,000 Btu/h, which is significantly lower than the statutory limit of 75,000 Btu/h (

see

42 U.S.C. 6291(27)(A) and the discussion in section III.A.2.b of this document).

In the January 2022 NOPR, DOE evaluated feedback from commenters indicating that most aspects of the test methods in ASHRAE 118.2-2022

were still applicable outside of its formal scope of coverage. 87 FR 1554, 1568 (Jan. 11, 2022). In the January 2022

NOPR, DOE stated that it has found through testing that models with rated storage volumes above 120 gallons or that can deliver water above 180 °F can be tested to DOE's appendix E test procedure, and, given the similarities between the currently applicable DOE test procedure and ASHRAE 118.2-2022, DOE tentatively determined that such models could also be tested using the methods in the ASHRAE test standard.

Id.

DOE did not receive any comments in response to this tentative conclusion in the January 2022 NOPR. Therefore, in evaluating the provisions within ASHRAE 118.2-2022, DOE has determined that its test methods remain applicable to all consumer water heaters and residential-duty commercial water heaters within the scope of appendix E (with the exception of low-temperature water heaters). As proposed in the January 2022 NOPR, this final rule makes several amendments to appendix E to harmonize with new provisions in ASHRAE 118.2-2022. Additionally, DOE determined that methods specified in annex B of ASHRAE 118.2 were applicable to the associated test procedures of this rulemaking, and, therefore, the Department has incorporated by reference ASHRAE 118.2-2022 for use in appendix E, with annex B being the directly applicable provision.

ASHRAE 118.2-2022 was published on January 24, 2022, which was after the January 2022 NOPR was published in the

Federal Register

on January 11, 2022; thus, the NOPR only discusses public review drafts of ASHRAE 118.2-2022 which were available at the time.

b. Provisions in ASHRAE 118.2-2022 Being Addressed by DOE

Thermal Break

ASHRAE 118.2-2022 specifies the use of a “thermal break” in the test set-ups shown for free-standing water heaters and water heaters supplied with a countertop enclosure (

see

Figures 1, 2, 3, 6, 7, 8, and 9 of ASHRAE 118.2-2022). A thermal break is optional in the ASHRAE 118.2-2022 test set-ups shown for wall-mounted water heaters (

see

Figures 4 and 5 of ASHRAE 118.2-2022).

ASHRAE 118.2-2022 defines a “thermal break” in section 3 as a nipple made of material that has thermal insulation properties (

e.g.

plastics) to insulate the bypass loop from the inlet piping. It should be able to withstand a pressure of 150 psi (1.034 MPa), and a temperature greater than the maximum temperature the water heater is designed to produce. A thermal break is added to the test set-up to prevent heat from traveling up the inlet piping into a bypass line, if one is utilized. (ASHRAE 118.2-2022 requires a bypass line to be installed, whereas the existing appendix E test procedure does not.) When purging the inlet piping before a draw, any heat that is transferred from the water heater through the inlet piping to the bypass line section would be lost, as the bypass line is replenished with cold supply water. The thermal break helps to prevent this heat loss.

In this rulemaking, DOE has sought feedback from stakeholders in the April 2020 RFI as to whether a thermal break should be required in the DOE test procedure regardless of whether a bypass line is used, and additionally, whether DOE should adopt a definition for this set-up component. 85 FR 21104, 21110 (April 16, 2020). The January 2022 NOPR discussed the mixed comments received on this topic. In summary, three commenters stated that a thermal break should be included in the test set-up regardless of whether there is a bypass or purge line; however, three others (including a testing standards organization, CSA Group) stated that a thermal break is not needed if no bypass or purge loop is present. Several commenters indicated that a standardized definition for a “thermal break” would be beneficial for repeatability of the test procedure. 87 FR 1554, 1569 (Jan. 11, 2022).

In the January 2022 NOPR, DOE explained that a bypass line is a method that test laboratories use to ensure inlet water temperatures are within the bounds of the test procedure (

i.e.,

within 58 °F ±2 °F by the first measurement of the draw), but its inclusion in the test set-up can create a condition whereby a constant low temperature can remove energy from the water heater at a higher rate than would be removed in the field. Because a bypass line is not the only approach to maintaining inlet conditions, DOE had tentatively determined that requiring a thermal break (and providing a definition for this component) would not be necessary.

Id.

BWC responded by indicating that it is not aware of any manufacturer or test laboratory omitting the use of a thermal break, and, therefore, DOE should adopt a definition for “thermal break” to ensure consistent results from laboratory to laboratory. The commenter recommended that a thermal break should be defined as “a plastic and thermally non-conductive material that can withstand a minimum temperature of 150 °F.” BWC also stated that its testing indicated that when a bypass line (also known as a “purge loop”) is used, all temperatures more consistently met the tolerance criteria in appendix E; furthermore, test results were more often out of tolerance when a bypass line was not used. BWC argued that as a result, use of a bypass line will remain common practice, and as such, thermal breaks will also continue to be used. (BWC, No. 33 at p. 3)

DOE has considered the comments received on this topic throughout this rulemaking, and, although DOE maintains that a thermal break would not be needed in all set-up cases, the Department has concluded that there is overwhelming support for establishing a standardized definition for “thermal break.” In order to address concerns regarding the repeatability of the test procedure (

i.e.,

various facilities maintaining a consistent set-up approach), DOE is adopting a definition for this component consistent with that in section 3 of ASHRAE 118.2-2022, but with minor modification. Specifically, DOE is defining “thermal break” as “a thermally non-conductive material that can withstand a pressure of 150 psi (1.034 MPa) at a temperature greater than the maximum temperature the water heater is designed to produce and is utilized to insulate a bypass loop, if one is used in the test set-up, from the inlet piping.” However, DOE is not requiring the use of a bypass loop or a thermal break in this final rule. DOE reasons that providing a definition for a thermal break will improve consistency in test set-ups when the testing agency opts to use a bypass loop with a thermal break.

FHR Test Flow Rates

Section 7.3.3.1 of ASHRAE 118.2-2022 indicates that the flow rate for non-flow-activated water heaters with rated storage volumes less than 20 gallons would be 1.5 ± 0.25 gallons per minute (gpm) (5.7 ± 0.95 liters (L)/minute (min)) when conducting the FHR test. Section 5.3.3, “First-Hour Rating Test,” of appendix E requires that water heaters with a storage volume less than 20 gallons be tested at 1.0 ± 0.25 gpm (3.8 ± 0.95 L/min). These flow rates are lower than the 3.0 ± 0.25 gpm (11.4 ± 0.95 L/min) required for water heaters with rated storage volumes greater than or equal to 20 gallons. Water heaters with low rated storage volumes (less than 20 gallons) and high input rates can potentially operate indefinitely (

i.e.,

instantaneously) at even the 3.0 ± 0.25 gpm (11.4 ± 0.95 L/min) flow rate. Therefore, when such products are tested as currently required by appendix E, the measured FHR is near the maximum possible value of 60 gallons (227 L)

and, as a result, these

products would be required to use the medium draw pattern according to Table I of appendix E. However, as discussed in the January 2022 NOPR, these models could be used in applications similar to water heaters that are required to test using the high draw pattern, and the existing method of testing these products may not best represent how they are used in the field. Instead, DOE finds that a flow rate of 1.5 ± 0.25 gpm (5.7 ± 0.95 L/min)—as introduced in ASHRAE 118.2-2022—would be sufficient to allow these products to be tested and rated in the high draw pattern. 87 FR 1554, 1569-1570 (Jan. 11, 2022).

At 1.0 ±0.25 gallons per minute during the 60-minute first-hour rating test, the maximum possible delivery capacity is 1.0 gallon per minute × 60 minutes = 60 gallons. At 1.5 ± 0.25 gallons per minute during the 60-minute first-hour rating test, the maximum possible delivery capacity is 1.5 gallon per minute × 60 minutes = 90 gallons.

In this rulemaking, DOE has sought information from commenters regarding the flow rate for the FHR test of non-flow-activated water heaters with rated storage volumes less than 20 gallons. DOE has also participated in the public review of ASHRAE 118.2 prior to the 2022 edition being released, leading up to the establishment of the 1.5 ± 0.25 gpm (5.7 ± 0.95 L/min) flow rate criteria for these products during the FHR test. DOE also performed testing on three electric storage water heaters less than 20 gallons to both the then currently applicable appendix E and ASHRAE 118.2-2022 flow rates and provided these test data in the January 2022 NOPR. The results indicated that changing the flow rate during the FHR test for water heaters with a rated storage volume less than 20 gallons from 1.0 ± 0.25 gpm (3.8 ± 0.95L/min) to 1.5 ± 0.25 gpm (5.7 ± 0.95 L/min) would have a relatively minimal impact on the FHR for water heaters with low input rates. For models with high input rates, the change in flow rate could significantly increase the FHR and result in some models being tested and rated for UEF using a higher draw pattern, which would provide ratings that are more representative of their actual use. Therefore, DOE proposed to adopt the higher flow rate of 1.5 ± 0.25 gpm (5.7 ± 0.95 L/min) for the FHR test of non-flow-activated water heaters with rated storage volumes less than 20 gallons. 87 FR 1554, 1570 (Jan. 11, 2022).

In response, AHRI indicated that the revised flow rate of 1.5 gpm may not be appropriate for models as small as 2 gallons, for which the proposed change could yield unrepresentative results for FHR. (AHRI, No. 40 at p. 4) AHRI also raised concerns about the accuracy of flow rates for smaller capacity water heaters. (AHRI, Jan. 27, 2022 Public Meeting Transcript, No. 27 at p. 41) Rheem generally supported DOE's proposal to align with ASHRAE 118.2-2022 on this issue. However, Rheem pointed out that the test data provided in the NOPR reflected consumer water heaters in only the very small draw pattern, so Rheem requested DOE to provide further test data and also to conduct testing on products near the division between the very small and low draw patterns. Rheem stated that a change in draw pattern will affect the UEF rating and will need to be taken into account. (Rheem, No. 31 at p. 2)

In response to the concerns raised by AHRI, DOE notes that its test data presented in the January 2022 NOPR were taken from samples in the very small draw pattern (

see

87 FR 1554, 1570 (Jan. 11, 2022)). DOE has additionally provided the storage volumes of the products which were tested in Table III.1 of this final rule. The samples were all approximately 2 gallons in storage volume, and the 1.5 gpm flow rate was found to be sufficiently representative for these products (the absolute value of the largest percent difference was less than 5 percent). Additionally, as stated in the January 2022 NOPR, the increase in flow rate did not cause any of these products to move from the very small draw pattern to the low draw pattern, which resolves a chief concern regarding the representativeness of the FHR results.

Id.

In response to Rheem's requests for additional data, DOE was not able to identify non-flow-activated water heaters less than 20 gallons closer to 18 gallons of FHR—the division between the very small and low draw patterns—in order to perform te

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