Energy Conservation Program for Consumer Products and Certain Commercial and Industrial Equipment: Test Procedures for Residential and Commercial Water Heaters

Federal RegisterNov 4, 2013

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DEPARTMENT OF ENERGY

10 CFR Parts 429, 430 and 431

[Docket Number EERE-2011-BT-TP-0042]

RIN 1904-AC53

Energy Conservation Program for Consumer Products and Certain Commercial and Industrial Equipment: Test Procedures for Residential and Commercial Water Heaters

AGENCY:

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

ACTION:

Notice of proposed rulemaking and announcement of public meeting.

SUMMARY:

The U.S. Department of Energy (DOE) proposes to revise its test procedure for residential water heaters and certain commercial water heaters established under the Energy Policy and Conservation Act. This rulemaking will fulfill DOE's statutory obligation for residential and certain commercial water heaters to review its test procedure for covered products and equipment at least once every seven years. In addition, this rulemaking will satisfy DOE's statutory obligation to develop a uniform efficiency descriptor for residential and commercial water heaters. The proposed test method would apply the same efficiency descriptor to all residential and certain commercial water heaters, and it would extend coverage to eliminate certain gaps in the current residential test procedure, update the simulated-use-test draw pattern, and update the water delivery temperature requirement. DOE is also announcing a public meeting to discuss and receive comments on issues presented in this test procedure rulemaking.

DATES:

Comments:

DOE will accept comments, data, and information regarding this notice of proposed rulemaking (NOPR) before and after the public meeting, but no later than January 21, 2014. See section V, “Public Participation,” for details.

Meeting:

DOE will hold a public meeting on December 6, 2013 from 9:00 a.m. to 4:00 p.m., in Washington, DC. The meeting will also be broadcast as a webinar. See section V, “Public Participation,” for webinar registration information, participant instructions, and information about the capabilities available to webinar participants.

ADDRESSES:

The public meeting will be held at the U.S. Department of Energy, Forrestal Building, Room 8E-089, 1000 Independence Avenue SW., Washington, DC 20585. To attend, please notify Ms. Brenda Edwards at (202) 586-2945. Please note that foreign nationals visiting DOE Headquarters are subject to advance security screening procedures. Any foreign national wishing to participate in the meeting should advise DOE as soon as possible by contacting Ms. Edwards at the phone number above to initiate the necessary procedures. Please also note that any person wishing to bring a laptop computer into the Forrestal Building will be required to obtain a property pass. Visitors should avoid bringing laptops, or allow an extra 45 minutes. Persons may also attend the public meeting via webinar. For more information, refer to section V, “Public Participation,” near the end of this notice of proposed rulemaking.

Interested persons are encouraged to submit comments using the Federal eRulemaking Portal at

www.regulations.gov

. Follow the instructions for submitting comments. Alternatively, interested persons may submit comments, identified by docket number EERE-2011-BT-TP-0042 and/or RIN 1904-AC53, by any of the following methods:

•

Email: HeatingProducts-2011-TP-0042@ee.doe.gov

. Include EERE-2011-BT-TP-0042 and/or RIN 1904-AC53 in the subject line of the message. Submit electronic comments in WordPerfect, Microsoft Word, PDF, or ASCII file format, and avoid the use of special characters or any form of encryption.

•

Postal Mail:

Ms. Brenda Edwards, U.S. Department of Energy, Building Technologies Office, Mailstop EE-2J, 1000 Independence Avenue SW., Washington, DC 20585-0121. If possible, please submit all items on a compact disc (CD), in which case it is not necessary to include printed copies.

•

Hand Delivery/Courier:

Ms. Brenda Edwards, U.S. Department of Energy, Building Technologies Office, 950 L'Enfant Plaza SW., 6th Floor, Washington, DC 20024. Telephone: (202) 586-2945. If possible, please submit all items on a CD, in which case it is not necessary to include printed copies.

Instructions:

All submissions received must include the agency name and docket number and/or RIN for this rulemaking. No telefacsimilies (faxes) will be accepted. For detailed instructions on submitting comments and additional information on the rulemaking process, see section V of this document (Public Participation).

Docket:

The docket is available for review at including Federal Register notices, public meeting attendee lists and transcripts, comments, and other supporting documents/materials. All documents in the docket are listed in the index. However, not all documents listed in the index may be publicly available, such as information that is exempt from public disclosure.

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

http://www.regulations.gov/#!docketDetail;D=EERE-2011-BT-TP-0042

. This Web page contains a link to the docket for this notice of proposed rulemaking on the site. The Web page contains simple instructions on how to access all documents, including public comments, in the docket. See section V, “Public Participation,” for information on how to submit comments through

www.regulations.gov

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

Brenda.Edwards@ee.doe.gov

FOR FURTHER INFORMATION CONTACT:

Ms. Ashley Armstrong, U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Office, EE-2J, 1000 Independence Avenue SW., Washington, DC 20585-0121. Telephone: (202) 586-6590. Email:

Ashley.Armstrong@ee.doe.gov

Mr. Eric Stas, U.S. Department of Energy, Office of the General Counsel, GC-71, 1000 Independence Avenue SW., Washington, DC 20585-0121. Telephone: (202) 586-9507. Email:

Eric.Stas@hq.doe.gov

For information on how to submit or review public comments, contact Ms. Brenda Edwards, U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Office, EE-2J, 1000 Independence Avenue SW., Washington, DC 20585-0121. Telephone: (202) 586-2945. Email:

Brenda.Edwards@ee.doe.gov

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Authority and Background

II. Summary of the Notice of Proposed Rulemaking

III. Discussion

A. Scope

1. Coverage Range of Uniform Metric and Test Procedure

2. Storage Capacity Limits

3. Input Capacity Limits

4. Electric Instantaneous Water Heaters

B. Uniform Efficiency Descriptor

C. Draw Pattern

D. Instrumentation

E. Discrete Performance Tests

F. Test Conditions

1. Water Delivery Temperature

2. Ambient Temperature and Relative Humidity

3. Laboratory Airflow

G. Annual Energy Consumption Calculation

H. Conversion of Existing Energy Factor Ratings

I. Other Issues

J. Certification, Compliance, and Enforcement Issues

K. Reference Standards

L. Compliance With Other EPCA Requirements

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Order 12866

B. Review Under the Regulatory Flexibility Act

C. Review Under the Paperwork Reduction Act of 1995

D. Review Under the National Environmental Policy Act of 1969

E. Review Under Executive Order 13132

F. Review Under Executive Order 12988

G. Review Under the Unfunded Mandates Reform Act of 1995

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

I. Review Under Executive Order 12630

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

K. Review Under Executive Order 13211

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

V. Public Participation

A. Attendance at the Public Meeting

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

C. Conduct of the Public Meeting

D. Submission of Comments

E. Issues on Which DOE Seeks Comment

VI. Approval of the Office of the Secretary

I. Authority and Background

Title III, Part B

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

These include residential water heaters, one subject of today's notice of proposed rulemaking. (42 U.S.C. 6292(a)(4)) Title III, Part C

of EPCA, Public Law 94-163 (42 U.S.C. 6311-6317, as codified), added by Public Law 95-619, Title IV, Sec. 441(a), established the Energy Conservation Program for Certain Industrial Equipment, which includes the commercial water-heating equipment that is another subject of this rulemaking. (42 U.S.C. 6311(1)(K))

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

All references to EPCA in this document refer to the statute as amended through the American Energy Manufacturing Technical Corrections Act (AEMTCA), Public Law 112-210 (Dec. 18, 2012).

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

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

Under 42 U.S.C. 6293, EPCA sets forth the criteria and procedures that DOE must follow when prescribing or amending test procedures for residential water heaters. EPCA provides, in relevant part, that any test procedures prescribed or amended under this section must 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 must not be unduly burdensome to conduct. (42 U.S.C. 6293(b)(3)) In addition, if DOE determines that a test procedure amendment is warranted, it must publish proposed test procedures and offer the public an opportunity to present oral and written comments on them. (42 U.S.C. 6293(b)(2))

For commercial water heaters, EPCA requires that if the test procedure referenced in the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 90.1 is updated, DOE must update its test procedure to be consistent with the amended test procedure in ASHRAE Standard 90.1, “Energy Standard for Buildings Except Low-Rise Residential Buildings,” unless DOE determines by rule published in the

Federal Register

and supported by clear and convincing evidence, that the amended test procedure is not reasonably designed to produce test results which reflect the energy efficiency, energy use, or estimated operating costs of that type of ASHRAE equipment during a representative average use cycle. In addition, DOE must determine that the amended test procedure is not unduly burdensome to conduct. (42 U.S.C. 6314(a)(2) and (4))

In any rulemaking to amend a test procedure, DOE must determine the extent to which the proposed test procedure would alter the product's measured energy efficiency. (42 U.S.C. 6293(e)(1)) If DOE determines that the amended test procedure would alter the measured efficiency of a covered product, DOE must amend the applicable energy conservation standard accordingly. (42 U.S.C. 6293(e)(2))

Further, the Energy Independence and Security Act of 2007 (EISA 2007) amended EPCA to require that at least once every 7 years, DOE must review test procedures for all covered products and either amend test procedures (if the Secretary determines that amended test procedures would more accurately or fully comply with the requirements of 42 U.S.C. 6293(b)(3) for residential products or 42 U.S.C. 6314(a)(2)-(3) for commercial equipment) or publish notice in the

Federal Register

of any determination not to amend a test procedure. (42 U.S.C. 6293(b)(1)(A); 42 U.S.C. 6314(a)(1)(A)) Under this requirement, DOE must review the test procedures for residential water heaters not later than December 19, 2014 (

i.e.,

7 years after the enactment of EISA 2007), and DOE must review the test procedures for commercial water heaters not later than May 16, 2019 (

i.e.,

7 years after the last final rule for commercial water heater test procedures

). Thus, the final rule resulting from this rulemaking will satisfy the requirement to review the test procedures for residential and certain commercial water heaters every seven years.

On May 16, 2012, DOE published a final rule in the

Federal Register

amending the test procedures for commercial water heaters. 77 FR 28928.

DOE's test procedure for residential water heaters is found in the Code of Federal Regulations (CFR) at 10 CFR 430.23(e) and 10 CFR part 430, subpart B, appendix E. The test procedure includes provisions for determining the energy efficiency (energy factor (EF)), as well as the annual energy consumption of these products. DOE's test procedure for commercial water heaters is found at 10 CFR 431.106; that test procedure incorporates by reference American National Standards Institute (ANSI) Z21.10.3,

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

and provides a method for determining the thermal efficiency and standby loss of this equipment.

In addition to the test procedure review provision discussed above, EISA 2007 also amended EPCA to require DOE to amend its test procedures for all covered residential products to include measurement of standby mode and off mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) Consequently, DOE recently completed a rulemaking to

consider amending its test procedure for residential water heaters to include provisions for measuring the standby mode and off mode energy consumption of those products. Pursuant to the requirements of EPCA, DOE published a notice of proposed rulemaking (NOPR) in the

Federal Register

on August 30, 2010, for three different residential heating products (water heaters, pool heaters, and direct heating equipment) related to standby mode and off mode energy consumption, but the NOPR proposed no amendments to the DOE test procedure for residential water heaters because DOE tentatively concluded that standby mode and off mode energy consumption was already accounted for in the existing DOE test method.

75 FR 52892, 52895. Subsequently, DOE published a final rule in the

Federal Register

on December 17, 2012, which affirmed its conclusion that no changes were needed to the existing test procedure for residential water heaters. 77 FR 74559, 74561-74562. However, that rulemaking was limited to consideration of test procedure amendments to address the above-referenced standby mode and off mode requirements; it did not address several other potential issues in DOE's existing test procedure for residential water heaters. DOE addresses these issues in today's NOPR.

For more information, please visit DOE's Web site at:

http://www1.eere.energy.gov/buildings/appliance_standards/residential/waterheaters.html

On October 12, 2011, DOE published in the

Federal Register

a request for information (RFI) that identified and requested comment on a number of issues regarding the test procedures for residential water heaters. 76 FR 63211. DOE accepted comments and information on the RFI until November 28, 2011, and considered all feedback received when developing the proposals contained in this notice. Each of the issues raised in the RFI is discussed in detail in section III, along with comments received on the issues and DOE's responses. In addition, several topics not addressed in the RFI but brought up by interested parties in their comments are discussed in section III of this NOPR.

On December 18, 2012, the American Energy Manufacturing Technical Corrections Act (AEMTCA), Public Law 112-210, was signed into law. In relevant part, it amended EPCA to require that DOE publish a final rule establishing a uniform efficiency descriptor and accompanying test methods for covered residential water heaters and commercial water heating equipment within one year of the enactment of AEMTCA. (42 U.S.C. 6295(e)(5)(B)) The final rule must replace the current energy factor, thermal efficiency, and standby loss metrics with a uniform efficiency descriptor. (42 U.S.C. 6295(e)(5)(C)) AEMTCA requires that, beginning one year after the date of publication of DOE's final rule establishing the uniform descriptor, the efficiency standards for covered water heaters must be denominated according to the uniform efficiency descriptor established in the final rule (42 U.S.C. 6295(e)(5)(D)), and that DOE must develop a mathematical conversion factor for converting the measurement of efficiency for covered water heaters from the test procedures and metrics currently in effect to the new uniform energy descriptor. (42 U.S.C. 6295(e)(5)(E)(i)-(ii)) After the effective date of the final rule, covered water heaters shall be considered to comply with the final rule and with any revised labeling requirements established by the Federal Trade Commission (FTC) to carry out the final rule, if the covered water heater was manufactured prior to the effective date of the final rule and complies with the efficiency standards and labeling requirements in effect prior to the final rule. (42 U.S.C. 6295(e)(5)(K))

AEMTCA also requires that the uniform efficiency descriptor and accompanying test method apply, to the maximum extent practicable, to all water-heating technologies currently in use and to future water-heating technologies. (42 U.S.C. 6295(e)(5)(H)) AEMTCA 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))

AEMTCA outlines DOE's various options for establishing a new uniform efficiency descriptor for water heaters. The options that AEMTCA provides to DOE include: (1) A revised version of the energy factor descriptor currently in use; (2) the thermal efficiency and standby loss descriptors currently in use; (3) a revised version of the thermal efficiency and standby loss descriptors; (4) a hybrid of descriptors; or (5) a new approach. (42 U.S.C. 6295(e)(5)(G)) Lastly, AEMTCA requires that DOE invite stakeholders to participate in the rulemaking process, and that DOE contract with the National Institute of Standards and Technology (NIST), as necessary, to conduct testing and simulation of alternative descriptors identified for consideration. (42 U.S.C. 6295(e)(5)(I)-(J))

DOE published an RFI on January 11, 2013 requesting input on the various issues pertaining to water heaters discussed in AEMTCA. 78 FR 2340. The feedback received from stakeholders was taken into consideration and is discussed further in section III of this NOPR.

II. Summary of the Notice of Proposed Rulemaking

In this NOPR, DOE proposes to modify the current test procedures for residential water heaters and certain commercial water heaters. The proposed amendments would modify the test procedure to be more representative of conditions encountered in the field (including modifications to both the test conditions and the draw patterns) and expand the scope of the test procedure to apply to certain commercial water heaters and certain residential water heaters that are currently not covered by the test procedure. The following paragraphs summarize these proposed changes.

DOE proposes to modify the test procedure for water heaters to establish a uniform descriptor that can be applied to: (1) All residential water heaters (including certain residential water heaters that are covered products under EPCA's definition of “water heater” at 42 U.S.C. 6291(27), but that are not covered under the existing test method); and (2) to certain commercial water heaters that have residential applications. This includes the proposed establishment of test procedure provisions that are applicable to water heaters with storage volumes between 2 gallons (7.6 L) and 20 gallons (76 L), and the proposed creation of a definition for “electric instantaneous water heater.” In addition, DOE proposes to establish a new equipment class of commercial water heaters and corresponding definition for “light commercial water heater.” DOE proposes to require water heaters that would be classified as “light commercial” to be tested using the test procedure for the uniform efficiency descriptor being proposed in this NOPR.

DOE is also proposing the use of multiple draw patterns for testing water heaters, with certain draw patterns prescribed as a function of equipment capacity. Further, DOE proposes updates to the water heater draw pattern to be more reflective of actual field usage based on recent field test data. Lastly, DOE is modifying the water delivery temperature requirement to better reflect conditions as seen in typical installations in the field.

III. Discussion

In response to the October 2011 RFI, DOE received 19 written comments related to water heaters from the following interested parties: Pacific Gas and Electric Company (PGE), Applied Energy Technology (AET), Davis Energy Group, American Council for an Energy-Efficient Economy (ACEEE), Southern California Edison (SCE), National Renewable Energy Laboratory (NREL), Natural Resources Canada (NRCan), Natural Resources Defense Council (NRDC), Air-Conditioning, Heating, and Refrigeration Institute (AHRI), Northwest Energy Efficiency Alliance (NEEA), American Gas Association (AGA), National Propane Gas Association (NPGA), A.O. Smith Corporation (AO Smith), Bradford White Corporation (Bradford White), Lochinvar, Stone Mountain Technologies, Bosch Thermotechnology Corp. (Bosch), General Electric Company (GE), and ASHRAE.

In response to the January 2013 RFI, DOE received 18 written comments from the following interested parties: NREL, Bradford White, AGA, NPGA, AHRI, AO Smith, joint efficiency advocates (joint comment),

GE, NEEA, Rheem Manufacturing Company (Rheem), American Public Gas Association (APGA), Edison Electric Institute (EEI), Heat Transfer Products Inc. (HTP), Natural Resources Canada (NRCan), Seisco International Limited (Seisco), Aquarensics, and two separate comments from the University of Houston—Clear Lake (UHCL1, UHCL2).

ACEEE submitted a joint comment on behalf of ACEEE, the Appliance Standards Awareness Project (ASAP), the National Consumer Law Center (NCLC), the Natural Resources Defense Council (NRDC), the Northeast Energy Efficiency Partnerships (NEEP), and the Northwest Power and Conservation Council (NPCC).

These interested parties commented on a range of issues, including those identified by DOE in the October 2011 RFI and the January 2013 RFI, as well as several other pertinent issues. The issues on which DOE received comment, as well as DOE's response to those comments and the resulting proposed changes to the test procedures for water heaters, are discussed in the subsections immediately below.

A. Scope

DOE's test procedures for residential water heaters codified at 10 CFR 430.23(e) and 10 CFR part 430, subpart B, appendix E address gas-fired, electric, and oil-fired storage-type (

i.e.,

storage volume not less than 20 gallons (76 L)) and gas-fired and electric instantaneous-type (

i.e.,

storage volume less than 2 gallons (7.6 L)) water heaters. However, the DOE test procedure does not define “electric instantaneous water heater.” In addition, it does not address the following types of products: (1) Gas-fired water heaters that have a storage volume at or above 2 gallons and less than 20 gallons (76 L); (2) electric storage water heaters with storage volume less than 20 gallons (76 L); and (3) storage water heaters with very large storage capacities, including oil-fired water heaters with storage volumes greater than 50 gallons (190 L), gas-fired water heaters with storage volumes above 100 gallons (380 L), and electric water heaters with storage volumes above 120 gallons (450 L). As discussed in the following sections, DOE proposes to expand the scope of coverage of its test method so that it is applicable to all products that meet the definition of residential water heater, including those products listed above which are currently not addressed by the existing DOE test method. DOE is also revising 10 CFR 430.32(d) to clarify the applicability of the existing standards with respect to the expanded test procedure scope.

DOE's test procedures for commercial water heaters are found at 10 CFR 431.106. In terms of capacity, the procedures for commercial water heaters cover storage water heaters with an input rating up to 4,000 British thermal units (Btu) per hour (Btu/h) per gallon of stored water, instantaneous water heaters with input ratings not less than 4,000 Btu/h per gallon of stored water, and hot water supply boilers with input ratings from 300,000 Btu/h to 12,500,000 Btu/h and of at least 4,000 Btu/h per gallon of stored water. Units using natural gas, oil, or electricity are covered by these test methods.

EPCA includes definitions for both residential and commercial water heaters that set the scope of DOE's authority for these products. (42 U.S.C. 6291(27); 42 U.S.C. 6311(12)) As required by AEMTCA, DOE proposes to create a uniform metric and test method for all covered water heaters,

regardless of whether a particular water heater falls under the scope of residential water heaters or commercial water heaters as defined in EPCA. In doing so, DOE also proposes to expand the scope of the test procedure to include definitions and test methods for the types of products noted above that are not covered by DOE's residential test procedure. DOE identified these topics as issues for comment in the October 2011 RFI and the January 2013 RFI. 76 FR 63211, 63212-63213 (Oct. 12, 2011); 78 FR 2340, 2344-2346 (Jan. 11, 2013).

As provided by 42 U.S.C. 6295(e)(5)(F), DOE is proposing to allow for the exclusion from the uniform efficiency descriptor of certain commercial water heaters that do not have a residential use and can be clearly described in the final rule and are effectively rated using the thermal efficiency and standby loss descriptors. The water heaters that DOE is proposing to exclude are discussed further in section III.A.1.

1. Coverage Range of Uniform Metric and Test Procedure

In the January 2013 RFI, DOE requested comment on whether the uniform efficiency descriptor required by AEMTCA should apply to all types of residential and commercial water heaters covered by EPCA, in addition to hot water supply boilers and unfired hot water storage tanks. In requesting comment, DOE acknowledged that AEMTCA provides for the possibility of an exclusion for certain water heaters from the uniform efficiency metric and accompanying test method. 78 FR 2340, 2345-46 (Jan. 11, 2013).

DOE received 7 comments that opposed DOE's tentative interpretation that AEMTCA requires the uniform descriptor to apply to all types of residential and commercial water heaters and indicated that DOE should utilize the statutory provision permitting an exclusion for any specific category of otherwise covered water heaters that do not have a residential use. (Bradford White, No. 30 at p. 2; AHRI, No. 33 at p. 1; AO Smith, No. 34 at p. 1; Joint comment, No. 35 at p. 2; NEEA, No. 37 at p. 2; Rheem, No. 38 at p. 2; HTP, No. 41 at p. 1)

Bradford White recommended that the uniform efficiency descriptor be limited to water heaters with inputs less than 200,000 Btu/h, which would cover those water heaters intended for residential applications. (Bradford White, No. 30 at p. 2) AHRI, AO Smith, Rheem, and HTP indicated that the legislation was intended to apply to residential products only and that development of a uniform metric and test method for all water heaters is not realistic given the substantially different duty cycles between water heaters meant for commercial applications and those meant for residential applications. (AHRI, No. 33 at pp. 1-2; AO Smith, No. 34 at p. 1; Rheem, No. 38 at p. 2; HTP, No. 41 at p. 1) The joint commenters supported a realignment of the scope that includes all water heaters except those clearly designed to deliver large amounts of hot water. (Joint comment, No. 35 at p. 2) NEEA recommended that DOE should focus on water heaters

meant for residential and small commercial applications. (NEEA, No. 37 at p. 2) No commenters supported DOE's tentative interpretation that AEMTCA requires the uniform descriptor to apply to all types of residential and commercial water heaters.

All references to comments received in response to the October 2011 and January 2013 RFI's identify the commenter, the identification number applied by DOE, and the page of the comment package on which the particular point has been discussed.

After considering the comments received, DOE proposes to exclude from the uniform efficiency descriptor any specific category of water heater that does not have a residential use. As noted above, AEMTCA provides that DOE can exclude from the uniform descriptor any specific categories of covered water heaters that do not have a residential use, can be clearly described in the final rule, and are effectively rated using the current thermal efficiency and standby loss descriptors. (42 U.S.C. 6295(e)(5)(F)) DOE received 13 comments regarding how to define water heaters that do not have a residential application. In light of these comments, DOE proposes to define a new classification of commercial water heaters for which the uniform efficiency descriptor would apply (

i.e.,

“light commercial water heaters”), which DOE believes can be clearly distinguished from the commercial water heaters for which the uniform descriptor would not apply under this proposal. DOE believes that the current metrics for commercial water heaters that are used only in commercial settings are appropriate and adequate to characterize the performance of such commercial water heaters. Commercial water heaters typically cycle less than residential water heaters due to longer run-times followed by standby periods. (Residential water heaters are typically subject to a number of small draws and short on-times throughout the day.) As a result, cycling losses of water heaters used in commercial applications are generally not as significant as those used in residential applications. Thus, DOE believes that thermal efficiency and standby loss metrics adequately characterize the efficiency in active and standby modes, respectively.

AHRI, AO Smith, and HTP suggested that the following characteristics may be suitable to distinguish water heaters intended for non-residential use: (1) Designed to deliver water at a thermostatically controlled temperature of 180 °F or more; (2) bear a Code Symbol Stamp signifying compliance with the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code; and (3) require electricity as the primary energy source and require the use of 3-phase external supply. (AHRI, No. 33 at p. 2; AO Smith, No. 34 at p. 1; HTP, No. 41 at p. 2) The joint commenters likewise stated that water heaters utilizing 3-phase electric power, designed to deliver water above 180 °F, and falling under the guise of the ASME pressure vessel code are not typical of residential applications. (Joint comment, No. 35 at p. 2) NEEA commented that there are many water heaters with features that make them unsuitable for residential and small commercial applications and provided examples of units with set points of 180 °F or higher, 3-phase power, and large input ratings and volumes. (NEEA, No. 37 at p. 2) AHRI, AO Smith, Rheem, and HTP also provided tables of rated inputs and storage volumes to distinguish water heaters that are not intended for residential applications. (AHRI, No. 33 at p. 2; AO Smith, No. 34 at p. 1; Rheem, No. 38 at p. 2; HTP, No. 41 at p. 2) Those limits are grouped by water heater type and are shown in Table III.1.

Table III.1—Suggested Capacity Limitations for Defining Non-Residential Water Heaters

Water heater type

Indicator of non-residential application by commenter

Gas-fired storage

AHRI, Rheem: Rated input >100 kBtu/h; Rated storage volume <20 gallons and >100 gallons.

AO Smith: Rated Input > 100kBtu/h; Rated storage volume >100 gallons.

HTP: Rated input >150 kBtu/h; Rated storage volume <20 gallons and >120 gallons.

Oil-fired storage

AHRI, AO Smith, Rheem: Rated input >140 kBtu/h; Rated storage volume >50 gallons.

Electric storage

AHRI, Rheem, HTP: Rated input >12 kW; Rated storage volume <20 gallons and >120 gallons.

AO Smith: Rated Input >12 kW; Rated storage volume >120 gallons.

Heat Pump with Storage

AHRI, AO Smith, Rheem, HTP: Rated current >24 Amperes; Rated voltage >250 V; Rated storage volume >120 gallons.

Gas-fired instantaneous

AHRI, AO Smith, Rheem, HTP: Rated input >200 kBtu/h; Water volume >1 gallon per 4000 Btu/h of input.

Electric instantaneous

AHRI, Rheem: Rated input >12 kW; Water volume >2 gallons.

AO Smith: Rated input >25 kW; Water volume >2 gallons.

Oil-fired instantaneous

AHRI, Rheem, AO Smith: Rated input >210 kBtu/h; Water volume >2 gallons.

Bradford White recommended that the new descriptor be limited to water heaters with inputs less than 200,000 Btu/h because, according to the commenter, water heaters with inputs greater than or equal to 200,000 Btu/hr are not used in residential applications since such a high input is not required in these types of applications. (Bradford White, No. 30 at p. 2) AGA stated that efficiency descriptors and test methods are best developed through consensus-based processes and referred DOE to the scope that is currently present in ASHRAE Standard 118.2,

Method of Testing for Rating Residential Water Heaters.

(AGA, No. 31 at 2)

Upon considering these comments, DOE agrees with commenters that a unit requiring three-phase electricity would nearly always be used only in a commercial setting, as residential homes are wired almost exclusively for single-phase power. Likewise, DOE agrees with commenters that units with an ASME pressure vessel rating or units capable of delivering water at temperatures at or exceeding 180 °F would generally only be used in commercial settings. As a result, DOE proposes to use these three criteria as the basis for defining “light commercial” water heaters that have residential applications.

DOE also considered the input and storage capacity criteria proposed by stakeholders to differentiate commercial water heaters that would only be used in non-residential applications from commercial water heaters that could have residential applications. DOE notes that equipment that was once classified as residential based on input capacity or storage volume might now be installed in a commercial setting and vice versa. Given that such changes occur over time as new technologies develop, DOE is declining to propose criteria in this NOPR on an input capacity basis. Instead, DOE believes that the three criteria discussed in the preceding

paragraph are adequate to define the class of commercial water heaters that could have residential applications.

Consequently, DOE proposes to add the following definition of “light commercial water heater” to 10 CFR 431.102:

Light commercial water heater

means any gas-fired, electric, or oil storage or instantaneous commercial water heater that meets the following conditions:

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

(2) Is not capable of delivering hot water at temperatures of 180 °F or above; and

(3) Does not bear a Code Symbol Stamp signifying compliance with the requirements of the ASME Boiler and Pressure Vessel Code.

Although light commercial water heaters could have residential applications, DOE notes that the new “light commercial water heater” definition represents a type of water heater that, to a significant extent, is distributed in commerce for industrial or commercial use. These water heaters were and continue to be covered industrial equipment, and, if these proposals are finalized, will continue to be subject to the regulations in part 431 and the certification requirements for commercial and industrial equipment in part 429. Similarly, although DOE recognizes that some consumer water heaters may be installed in a commercial setting, those waters heaters are covered consumer products for the purposes of DOE regulations, the regulations in part 430 continue to apply, and they must be certified as consumer products under part 429.

If a commercial water heater does not meet all of these three conditions, it would be classified as a commercial water heater that would not be expected to be used in residential applications and would be subject to the current test methods prescribed in 10 CFR 431.106, which reference ANSI Z21.10.3. If a commercial water heater meets all three criteria, DOE proposes to consider it a “light commercial water heater,” which would be subject to the uniform efficiency descriptor and test method proposed in today's NOPR. Accordingly, DOE proposes to add a row to Table 1 of 10 CFR 431.106 specifying 10 CFR part 430, subpart B, Appendix E as the test method for this class of equipment. DOE seeks comment on both the proposed definition of “light commercial water heater” and the proposal to subject this equipment to the test methods at Appendix E. This is identified as issue 1 in section V.E, “Issues on Which DOE Seeks Comment.”

DOE also received comments recommending that certain types of water heaters should be excluded from the uniform descriptor for various reasons. NREL commented that storage tanks do not make a complete water heating system, so an energy factor is not appropriate. NREL elaborated that a rating using a standby loss coefficient could be appropriate. (NREL, No. 29 at pp. 3-4) AHRI, AO Smith, and HTP recommended that DOE exclude from the descriptor: (1) Unfired storage tanks because they do not actually heat water; (2) add-on heat pumps because DOE has previously determined that these are not covered products and they are not complete water heaters; and (3) hot water supply boilers because, by definition, they have inputs exceeding the values listed in the commenters' recommendations and because these products are all subject to the requirements of the ASME Boiler and Pressure Vessel Code (AHRI, No. 33 at pp. 4-5; AO Smith, No. 34 at p. 3; HTP, No. 41 at p. 5) Rheem expressed support for AHRI's list of exclusions. (Rheem, No. 38 at p. 2) NEEA recommended that DOE should exclude water storage tanks from the uniform descriptor because they are technically not water heaters and they simply store water heated elsewhere. NEEA also commented that unfired storage tanks should not be excused from all efficiency requirements since standby loss efficiency is important for all hot water storage vessels, regardless of where and how the water is heated. (NEEA, No. 37 at p. 2) Conversely, the joint commenters recommended that the uniform efficiency descriptor should be able to effectively measure the efficiency of electric heat pump water heaters without an integrated storage tank in the event it is included in future Federal coverage. (Joint comment, No. 35 at p. 5)

DOE has tentatively determined that certain commercial equipment such as unfired storage tanks and add-on heat pump water heaters are not appropriately rated using the uniform descriptor applicable to other water heaters. Unfired storage tanks are not complete water-heating systems and require additional equipment in the field to operate. Thus, DOE believes that other metrics may be more appropriate for these devices with limited functionality compared to actual water heaters, and that their performance as part of a complete water-heating system is so dependent upon other components of the system that use of the uniform descriptor may be unrepresentative of its performance as a system. For add-on heat pump water heaters, DOE agrees with stakeholders that DOE has previously determined that these are not covered residential products. As such, DOE only has authority to cover commercial add-on heat pumps; however, this equipment does not have residential applications, and, therefore, is not suitable for inclusion in the uniform efficiency descriptor. DOE has also tentatively determined that hot water supply boilers are more appropriately rated using the existing metrics for commercial water heaters, as this equipment has very high input ratings and are subject to the ASME Boiler and Pressure Vessel Code, and their use is similar to that of other commercial water heaters in commercial applications. DOE will address the types of water-heating equipment that are excluded from the uniform descriptor (

e.g.,

unfired storage tanks, add-on heat pump water heaters, and hot water supply boilers) in a subsequent test procedure rulemaking.

2. Storage Capacity Limits

Under the existing regulatory definitions, DOE's current residential water heater test procedures are not applicable to gas or electric water heaters with storage tanks that are at or above 2 gallons (7.6 L) and less than 20 gallons (76 L). In terms of the high end of the capacity range, the current DOE test procedure for residential water heaters only applies to gas-fired water heaters with storage volumes less than or equal to 100 gallons (380 L), electric resistance and heat pump storage water heaters with storage volumes less than or equal to 120 gallons (450 L), and oil-fired water heaters with storage volumes less than or equal to 50 gallons (190 L). 10 CFR part 430, subpart B, appendix E, sections 1.12.1, 1.12.2, and 1.12.4.

In the 1998 rulemaking establishing test procedures for residential water heaters, DOE proposed to include units with storage volumes between 2 and 20 gallons, but commenters raised concerns that the test procedure demand of 64.3 gallons per day was not appropriate for these small units. 63 FR 25996, 26000 (May 11, 1998). At that time, DOE concluded that the data to determine the appropriate daily hot water consumption did not exist and that alternative procedures proposed by commenters were not fully evaluated. For these reasons, the Department tabled consideration of the inclusion of these water heaters until a future revision of the DOE test procedure. In recent years, however, water heaters with such capacities have begun to populate the market. The definitions in

the DOE test procedure (cited above) specify that instantaneous-type water heaters have a storage volume of less than two gallons (7.6 L) and that electric or gas storage-type water heaters have a storage volume of 20 gallons (76 L) or more. The storage capacity of oil water heaters in the test method is not restricted by a lower limit, with the specification stating that an oil-fired storage water heater simply has a rated capacity less than or equal to 50 gallons (190 L). 10 CFR part 430, subpart B, appendix E, sections 1.7 and 1.12. The definition for “Storage-type Water Heater of More than 2 Gallons (7.6 Liters) and Less than 20 Gallons (76 Liters)” is currently reserved.

Id.

at section 1.12.5. DOE requested comment on the potential to address this gap in the October 2011 RFI, and received several comments from interested parties. 76 FR 63211, 63213 (Oct. 12, 2011).

DOE received 11 comments in support of the inclusion of water heaters with storage volumes between 2 and 20 gallons. (Bradford White, No. 2 at p. 1; PGE, No. 3 at p. 1; SCE, No. 4 at p. 1; Stone Mountain Technologies, No. 5 at p. 2; AO Smith, No. 8 at p. 1; NEEA, No. 9 at p. 2; AHRI, No. 12 at p. 1; NREL, No. 14 at p. 7; NRDC, No. 20 at p. 1; AET, No. 22 at p. 7; ACEEE, No. 24 at pp. 3-4). No comments were received opposed to this measure.

AHRI, AO Smith, Bradford White, and Lochinvar suggested that a distinct test procedure is needed for electric storage water heaters with volumes between 2 and 20 gallons since the current test method is not suited for such point-of-use products and that this test method measure only the standby loss of the unit. (Bradford White, No. 2 at p. 1; AO Smith, No. 8 at p.1; Lochinvar, No. 10 at p. 1; AHRI, No. 12 at p. 2) Stone Mountain Technologies stated further that all electric resistance water heaters should be subjected to only a standby loss test, because differences between models is almost solely based on standby losses. (Stone Mountain Technologies, No. 5 at p. 3) DOE has considered these points but has tentatively concluded that, for equity across water-heating technologies, all water heaters should be tested under a simulated-use profile as will be discussed in section III.C. DOE proposes a profile that is appropriate for point-of-use water heaters, so any concerns that the current test method is not suitable are addressed by the proposed test method. This profile will simulate the way that a point-of-use water heater is used in the field and will capture any operational characteristics that could affect its efficiency. DOE also believes that a simulated-use test will better capture any potential cycling losses or inefficiencies in meeting the demands imposed on all water heaters.

After considering the comments received, DOE proposes to expand the scope of the water heater test procedure for the uniform efficiency descriptor to include water heaters with storage volumes between 2 and 20 gallons. The proposed modifications will specify the method of test set-up (including instrumenting such water heaters), a test method to assess the delivery capacity, and the draw pattern that would be used to determine the energy efficiency of such units. The proposed amendments for water heaters with storage volumes between 2 and 20 gallons are discussed in detail in section III.C of today's notice of proposed rulemaking.

DOE is not aware of any residential water heaters available on the market with storage volumes above 100 gallons, 120 gallons, and 50 gallons for gas-fired, electric (resistance and heat pump), and oil-fired water heaters, respectively, that would be covered as residential products under EPCA. Due to the lack of water heaters with very large storage volumes that meet the definition of a residential “water heater,” DOE tentatively concluded in the October 2011 RFI that it is unnecessary to expand the scope of the test procedure to include gas-fired products over 100 gallons, electric products over 120 gallons, or oil-fired products over 50 gallons, and requested comment on this tentative conclusion. 76 FR 63211, 63213 (Oct. 12, 2011).

Four commenters (Bradford White, AO Smith, NEEA, AHRI) supported DOE's position to maintain the existing capacity limits for storage water heaters, while three commenters (Stone Mountain Technologies, NREL, AET) recommended that the test method be expanded to include all water heaters with storage volumes from 0 to 120 gallons. (Bradford White, No. 2 at p. 1; AO Smith, No. 8 at p. 1; NEEA, No. 9 at p. 2; AHRI, No. 12 at p. 1; Stone Mountain Technologies, No. 5 at p. 2; NREL, No. 14 at p. 8; AET, No. 22 at pp. 6-7) AET noted that the pressure vessel code from the American Society of Mechanical Engineers requires that vessels intended to store fluids under pressure must individually undergo a rigorous test and inspection procedure if they have volumes greater than 120 gallons. AET noted that because these test and certification procedures are expensive, manufacturers will avoid making products intended for residential use that require an ASME inspection and code stamp. For this reason, AET commented that the upper limit of 120 gallons would be appropriate for all residential water heaters. AET further suggests that expanding the volume limit to 120 gallons would prevent manufacturers from evading efficiency standards by marketing water heaters slightly larger than the currently specified limits. (AET, No. 22 at pp. 6-7)

The subsequent passage of AEMTCA has necessitated that DOE reconsider the scope of all water heater test procedures. DOE has considered these comments, as well as the provisions of AEMTCA, and proposes to expand the scope of the test procedure to include all covered water heaters that could have residential applications and remove the limitations on maximum storage volume that are currently in the residential test procedure for gas-fired, electric, and oil storage water heaters. The Department's authority to regulate water heaters is limited to those explicitly defined as covered products by EPCA. EPCA defines the term “water heater” as a product which utilizes oil, gas, or electricity to heat potable water for use outside the heater upon demand. (42 U.S.C. 6291(27)) Further, EPCA defines storage type units which include 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. EPCA also defines instantaneous type units, which are water heaters that 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. Lastly, EPCA defines covered heat pump type units, which have a maximum current rating of 24 amperes at a voltage no greater than 250 volts, and which are designed to transfer thermal energy from one temperature level to a higher temperature level for the purpose of heating water, and include all ancillary equipment such as fans, storage tanks, pumps, or controls necessary for the device to perform its function. Id.

For commercial water heating equipment, EPCA defines “storage water heater” as a water heater that heats and stores water within the appliance at a thermostatically controlled temperature for delivery on demand, and does not include units with an input rating of 4000 Btu per hour or more per gallon of stored water. EPCA also defines “instantaneous water heater” as a water

heater that has an input rating of at least 4000 Btu per hour per gallon of stored water. Lastly, EPCA defines the term “unfired hot water storage tank” as a tank used to store water that is heated externally. (42 U.S.C. 6311(12))

AEMTCA requires that the new metric apply to the extent possible to all water-heating technologies used in residential applications. (42 U.S.C. 6295(e)(5)(F) and (H)) DOE believes that the test method proposed in today's NOPR adequately addresses large water heaters regardless of storage volume, provided that they are used in residential applications. As noted previously in section III.A.1, DOE proposes to exclude units used only in non-residential applications, but DOE does not believe that storage volume alone would dictate whether a unit is residential or commercial. As noted by AET, the ASME pressure vessel code requires that vessels intended to store fluids under pressure must undergo a rigorous test and inspection procedure if they have volumes greater than 120 gallons. Any such products would be ASME pressure vessel rated, and under the definition of “light commercial water heater” proposed in section III.A.1, would not be subject to the uniform efficiency descriptor, which would effectively limit the maximum storage volume to 120 gallons for the purposes of using the uniform descriptor. For these reasons, DOE proposes to eliminate the maximum storage volume limitations from the residential water heater test procedure.

3. Input Capacity Limits

DOE's current residential water heater test procedure is not applicable to gas-fired instantaneous water heaters with input capacities at or below 50,000 Btu/h or at or above 200,000 Btu/h. 10 CFR Part 430, subpart B, Appendix E, section 1.7.2. In addition, the test procedure is not applicable to gas-fired storage water heaters with input capacities above 75,000 Btu/h, electric storage water heaters with input ratings above 12 kW, and oil-fired storage water heaters with input ratings above 105,000 Btu/h. 10 CFR Part 430, subpart B, Appnedix E, section 1.12.

DOE proposes to eliminate the minimum limit on the firing rate of instantaneous gas water heaters of 50,000 Btu/h, as AEMTCA requires that the new metric apply to the maximum extent practical to all water-heating technologies intended for residential application. (42 U.S.C. 6295(e)(5)(F) and (H)) As discussed in section III.C, DOE proposes to adopt multiple draw patterns that would vary based on the delivery capacity of the water heater. Because the draw pattern would be dependent upon delivery capacity, DOE believes that small gas-fired instantaneous units could be appropriately tested under the proposed procedure. Thus, DOE believes there is no reason to retain this lower limit on gas-fired instantaneous water heater delivery capacity.

Similarly, DOE proposes to remove the maximum input ratings for gas-fired, electric, and oil-fired storage water heaters, and for gas-fired instantaneous water heaters from the test procedure. DOE believes that the proposed test procedure, because it varies based on delivery capacity, is applicable to units with input capacities above those included in the current residential water heater test procedure. Although these maximum input limitations were based upon DOE's “water heater” definition at 42 U.S.C. 6291(27), because AEMTCA requires that the new metric apply to all water-heating technologies except those that do not have a residential use, DOE believes that such limits are no longer controlling or appropriate in terms of the scope of the water heaters test procedure. As discussed in section III.A.1, given the technology shifts that occur over time, DOE does not believe input capacity limitations to be a consistent indicator of whether a product has a residential use.

4. Electric Instantaneous Water Heaters

DOE's current test procedures do not contain a definition for “electric instantaneous water heater,” but rather have a space reserved to define that term. 10 CFR Part 430, subpart B, appendix E, section 1.7.1. EPCA defines “electric instantaneous water heater” as having an input capacity of 12 kilowatts (kW) or less. (42 U.S.C. 6291(27)(B)) As noted by commenters and discussed in section III.A.1, the heating power required for electric instantaneous water heaters intended for whole-home applications is typically much higher than the power capability commonly found in storage-type electric water heaters. Given the emergence of electric instantaneous water heaters on the market, DOE requested comment in the October 2011 RFI on addressing this gap in the test procedure by prescribing a definition specifically for the term “electric instantaneous water heater.” DOE noted in the RFI that although the 24-hour simulated use test in DOE's test procedure for instantaneous water heaters at 10 CFR Part 430, subpart B, appendix E, section 5.2.4 is titled “24-hour Simulated Use Test for Gas Instantaneous Water Heaters,” the method is also applicable for electric instantaneous water heaters. DOE requested comment on potential modifications to the DOE test procedure to address electric instantaneous water heaters.

DOE received thirteen comments in support of the proposal to amend DOE's water heater test procedure to include electric instantaneous water heaters. (Bradford White, No. 2 at p. 1; PGE, No. 3 at p. 1; SCE, No. 4 at p. 1; Stone Mountain Technologies, No. 5 at p. 2; AO Smith, No. 8 at p. 1; NEEA, No. 9 at p. 2; Lochinvar, No. 10 at p. 1; AHRI, No. 12 at p. 1; NREL, No. 14 at p. 9; NRDC, No. 20 at p. 1; Bosch, No. 17 at p. 1; AET, No. 22 at pp. 8-9; and ACEEE, No. 24 at p. 4.) DOE received no comments opposing such an inclusion. Bradford White, AO Smith, AHRI, NREL, AET, and ACEEE also suggested that the test procedure should be amended to cover electric instantaneous water heaters with heating rates higher than 12 kW in order to accommodate units that are meant to serve whole-home applications. (Bradford White, No. 2 at p. 1; AO Smith, No. 8 at p. 1; AHRI, No. 12 at p. 2; NREL, No. 14 at p. 9; AET, No. 22 at pp. 8-9; ACEEE, No. 24 at p. 4) AHRI and ACEEE suggested that the test procedure for electric instantaneous water heaters should be made applicable to water heaters with inputs up to 25 kW (AHRI, No. 12 at p. 2; ACEEE, No. 24 at p. 4), while Bradford White suggested an input limit of 35 kW (Bradford White, No. 2 at p. 1), and NREL recommended an input limit of 50 kW (NREL, No. 14 at p. 9). AET commented that the upper limit be based on a maximum current of 200 Amperes, which is the typical maximum value allowed in residences in the United States. (AET, No. 22 at pp. 8-9) In response to the January 2013 RFI, Aquarensics, UHCL1, UHCL2, and Seisco commented that the test method should cover electric instantaneous water heaters with input ratings in excess of 12 kW. (Aquarensics, No. 43 at p.1; UHCL1, No. 44 at p. 1; UHCL2, No. 45 at p. 1; Seisco, No. 47 at p. 1) Further, Aquarensics, UHCL1, UHCL2, and Seisco all commented that commercially-available electric instantaneous water heaters that are designed for residential applications have input ratings greater than the current limit of 12 kW for residential electric water heaters under EPCA. (Aquarensics, No. 43 at p. 2; UHCL1, No. 44 at p. 1; UHCL2, No. 45 at p. 1; Seisco, No. 47 at p. 3) Aquarensics and UHCL2 noted residential applications that used units with an input rating of 28 kW. UHCL1 commented that whole-house instantaneous water heaters typically require 25 kW to 35 kW.

Seisco stated that residential electric instantaneous water heaters having inputs above 30 kW are commonly built and have been used for residential applications since 1999. Seisco further stated that electric instantaneous water heaters with input ratings up to 35 kW are used for whole-house applications.

After considering the comments on the RFIs, DOE proposes to amend its water heaters test procedure to include applicable provisions for electric instantaneous water heaters, and to define the term “electric instantaneous water heater” as follows:

Electric Instantaneous Water Heater

means a water heater that uses electricity as the energy source, initiates heating based on sensing water flow, is designed to deliver water at a controlled temperature of less than 180 °F (82 °C), and has a manufacturer's specified storage capacity of less than 2 gallons (7.6 liters). The unit may use a fixed or variable power input.

DOE notes that the proposed definition would encompass both electric instantaneous water heaters that are residential (

i.e.,

with an input capacity of 12 kW or less) and commercial (

i.e.,

with an input capacity greater than 12 kW). Because water heaters both above and below 12 kW have residential applications, both types would be covered by the uniform efficiency descriptor. Today's proposed rule provides for a maximum flow rate test, as well as a test to obtain the energy efficiency expressed in terms of Energy Factor (EF). These tests are identical to those implemented for gas instantaneous water heaters.

B. Uniform Efficiency Descriptor

AEMTCA provided the following options for the uniform efficiency descriptor metric: (1) A revised version of the energy factor descriptor currently in use; (2) the thermal efficiency and standby loss descriptors currently in use; (3) a revised version of the thermal efficiency and standby loss descriptors; (4) a hybrid of descriptors; or (5) a new approach. (42 U.S.C. 6295(e)(5)(G)) In the January 2013 RFI, DOE requested comment on the appropriate metric to be used as the uniform descriptor. 78 FR 2340, 2344-45 (Jan. 11, 2013). Eight parties provided comments supporting the use of the energy factor metric, but obtained using a different method of test than provided in the current test procedure. (NREL, No. 29 at p. 1; Bradford White, No. 30 at p. 1; AHRI, No. 33 at p. 3; AO Smith, No. 34 at p. 2; GE, No. 36 at p. 1; NEEA, No. 37 at p. 1; Rheem, No. 38 at p. 3; HTP, No. 41 at p. 3) The joint comment indicated that the existing energy factor metric is inadequate and indicated support for a series of simulated use tests that would result in a revised energy factor. (Joint comment, No. 35 at p. 1) No comments were received that proposed the use of thermal efficiency, standby loss factor, or any new metrics.

NREL stated that the thermal efficiency and standby loss metrics are not suitable as primary metrics for residential applications, because they do not completely capture performance. (NREL, No. 29 at p. 1) AHRI and HTP indicated that the energy factor metric would enable testing agencies to build on prior experience in testing water heaters for residential applications, that it would result in an easier conversion from the current metric to the uniform descriptor, and that it can be technology neutral. (AHRI, No. 33 at pp. 3-4; HTP, No. 41 at p. 3) HTP also suggested a voluntary rating for combined water-heating and space-heating appliances based on ASHRAE Standard 124,

Methods of Testing for Rating Combination Space-Heating and Water-Heating Appliances.

(HTP, No. 41 at p. 4) AO Smith suggested that the uniform descriptor be given a qualifying name to distinguish it from the current energy factor, providing “New Energy Factor” as an example. (AO Smith, No. 34 at p. 2) GE indicated that an energy factor metric would be technology neutral and that it would minimize complexity in converting from the current metric to the uniform descriptor. (GE, No. 36 at p. 1)

NRCan provided a report documenting results of testing of two commercial water heaters that are marketed towards the residential sector under the existing residential test procedure. (NRCan, No. 42 at p. 1) The report did not identify any problems or concerns with testing these units under the existing test procedure.

Based on these comments, DOE proposes a modified version of the existing energy factor metric as the uniform descriptor for products covered under this test procedure. DOE believes that an energy factor that is derived from a simulated use test will provide a technology-neutral metric for the efficiency of water heaters intended for residential applications. The simulated use test will capture key performance aspects such as burner efficiency, standby loss, and cycling that affect energy efficiency seen by consumers. However, DOE will not adopt voluntary rating requirements for combination appliances at this time, as that is outside the scope of today's test procedure NOPR. Further, DOE does not plan to change the name, as suggested by A.O. Smith. The Department believes that because standards and ratings will be transitioned to the new metric and the old metric will be come obsolete, there will be little confusion by maintaining the name “energy factor.”

C. Draw Pattern

The term “draw pattern” describes the number, flow rate, length, and timing of hot water removal from the water heater during testing. Primary decisions in developing draw patterns include the total amount of water to be removed during the test and the number of draws during the test. The total amount of water taken in each draw, which is a function of the flow rate and the length of the draw, must also be specified. Finally, the spacing between those draws is needed to complete the specification of the draw pattern.

The current residential water heater test procedure includes a 24-hour simulated-use test for determining energy factor. 10 CFR Part 430, subpart B, appendix E, sections 5.1.5 and 5.2.4. The 24-hour test specifies that 6 draws of equal volume be removed from the water heater in the first 6 hours of the test for a total draw of 64.3 ± 1.0 gallons (243.4 ± 3.8 L).

Following the six draws, the water heater sits in an idle mode for the remainder of the 24-hour test.

Id.

The draw pattern is the same regardless of the type (e.g., gas-fired, electric resistance, oil-fired, heat pump, storage, instantaneous) and characteristics (

e.g.,

storage volume, input capacity) of the water heater.

10 CFR Part 430, subpart B, appendix E, section 5.1.5 currently states, “During the simulated use test, a total of 64. ±3 1.0 gallons (243 ± 2.8 liters) shall be removed.” DOE contends that the total is in error and should instead read “64.3 ± 1.0 gallons (243 ± 2.8 liters).” No correction is proposed at this time since the quantity will change in the proposed test procedure.

In the October 2011 RFI, DOE noted that recent data

10 11 12

suggest that the draw pattern can impact the energy factor of a water heater and can potentially offer an advantage to one type of water heater technology over another. 76 FR 63211, 63213 (Oct. 12, 2011). These studies also suggest that the existing draw pattern in the simulated use test may not be

representative of actual draw patterns to which water heaters are subjected in the field. Because different water heaters will be subjected to different field demands (consumer usage patterns) due to operational or performance differences, DOE proposes to revise the draw pattern to be more representative of typical usage patterns experienced in the field. DOE is also proposing to amend its test procedure to provide for different draw patterns for different water heaters based upon the characteristics of each water heater, such as the rate of hot water the unit can provide, the storage volume, and the heating rate (

i.e.,

input rate). In the October 2011 RFI, DOE sought comment on improvements that could be made to DOE's existing 24-hour simulated use test procedure for water heaters. Additional comments were sought by and provided in response to the January 2013 RFI.

Healy, WM, Ullah, T, and Roller, J., “Input-Output Approach to Predicting the Energy Efficiency of Residential Water Heaters—Testing of Gas Tankless and Electric Storage Water Heaters,” ASHRAE Transactions 117 (2011).

Hoeschele, M.A. and Springer, D.A., “Field and Laboratory Testing of Gas Tankless Water Heater Performance,”

ASHRAE Transactions

114 (2): 453-461 (2008).

Bohac, D, Schoenbauer, B., Hewett, M., Lobenstein, M.S., Butcher, T. “Actual Savings and Performance of Natural Gas Tankless Water Heaters,” Center for Energy and Environment Report for Minnesota Office of Energy Security (August 30, 2010).

DOE received 27 comments that addressed these issues. Four commenters (AGA, Bosch, General Electric, and Rheem) recommended that DOE maintain the test procedure as it currently stands. AGA argued the importance of consistency with previous ratings. (AGA, No. 13 at p. 1) Bosch commented that the current test procedure covers a large quantity of applications without trying to estimate the usage for any given household. (Bosch, No. 17 at p. 2) General Electric wrote that the six-draw requirement is appropriate for medium-volume water heaters. (GE, No. 21 at pp. 1-2) Rheem suggested that the added scope of covered products called for by AEMTCA would best be handled by maintaining the existing residential water heater test procedure at this time while continuing to pursue an amended test method. (Rheem, No. 38 at p. 3) Rheem further argued that such an incremental approach would allow manufacturers to continue on a path to meet minimum efficiency requirements imposed by amended energy conservation standards.

In total, DOE received twenty-three comments recommending that the Agency move away from the six-draw requirement as currently specified in the DOE test procedure (although certain of these comments were multiple submissions from the same interested party). (Bradford White, No. 2 at p. 2; PGE, No. 3 at p. 2; SCE, No. 4 at p. 2; Stone Mountain Technologies, No. 5 at p. 2; AO Smith, No. 8 at p. 2; NEEA, No. 9 at p. 2; NPGA, No. 11 at pp. 1-2; AHRI, No. 12 at p. 2; NREL, No. 14 at pp. 1-2; GTI, No. 15 at p. 2; NRCan, No. 16 at pp. 1-2; NRDC, No. 20 at p. 2; AET, No. 22 at p. 2; ACEEE, No. 24 at p. 1; NREL, No. 29 at p. 2; Bradford White, No. 30 at p. 2; AHRI, No. 33 at p. 4; AO Smith, No. 34 at p. 3; Joint comment, No. 35 at p. 1; GE, No. 36 at p. 1; NEEA, No. 37 at p. 3; APGA, No. 39 at p. 2; AHRI, No. 46 at p. 1)

Bradford White indicated its support for a 24-hour simulated use test because it is “technology blind.” (Bradford White, No. 2 at p. 2) PGE and SCE recommended that the draw pattern be modified to reduce bias towards tankless water heaters, and that different draw patterns be applied based on the capacity of the water heater. (PGE, No. 3 at p. 2; SCE, No. 4 at p. 2) Stone Mountain Technologies indicated that recent studies have shown that the efficiency of most gas-fired tankless models is overstated using the current DOE test procedure. The commenter stated that this finding, along with the addition of small water heaters within the scope of the test procedure, necessitate a modification to the current draw pattern. Further, Stone Mountain Technologies opined that an appropriate number of draws for a practical test method would be between 10 and 15. (Stone Mountain Technologies, No. 5 at p. 2) AO Smith and AHRI supported revising the test procedure while retaining the simulated-use concept and indicated that an AHRI industry effort is underway to develop a modified draw pattern. (AO Smith, No. 8 at p. 2; AHRI, No. 12 at p. 2; AHRI, No. 33 at p. 4; AO Smith, No. 34 at p. 3) AHRI submitted a proposed revised energy factor test method to DOE, which was considered for today's NOPR and is discussed below. (AHRI, No. 46, pp. 1-7) NEEA stated that it is clear that the draw pattern used in the current test procedure bears no resemblance to that seen in actual use, and accordingly, the current draw pattern should be abandoned. (NEEA, No. 9 at p. 2) NREL commented that the draw patterns in the new test must be statistically representative of actual usage, meaning that the frequency distributions of key variables in the test procedure (such as volume of draws and timing between draws) are reasonably matched to field data. Furthermore, it commented that DOE should ensure that any proposed test draw profile must be consistent with all relevant statistical distributions determined from the database of hot water draws created by the Lawrence Berkeley National Laboratory (LBNL). (NREL, No. 14 at pp. 1-2, 8) NREL also mentioned the efforts underway by ASHRAE to develop a test method based on multiple draw patterns that have different total draw volumes that are appropriate for water heaters of different sizes. (NREL, No. 29 at p. 2) NEEA likewise discussed these efforts by ASHRAE. (NEEA, No. 27 at p. 2)

GTI discussed the effect of a greater number of draws during the test on the efficiency rating of instantaneous water heaters, and presented data on estimated energy factors and efficiencies under different draw patterns. (GTI, No. 15 at pp. 6-9) NRCan discussed changes being proposed to the committee responsible for Canadian Standards Association (CSA) P.3—

Testing Method for Measuring Energy Consumption and Determining Efficiencies of Gas-Fired Storage Water Heaters.

The committee is considering changing the current draw pattern and replacing it with a new pattern of 10 to 15 draws spread throughout the day, with the volume and time of each draw varying. NRCan also provided data from a field study in Ontario that included information on hot water draw patterns. (NRCan, No. 16 at p. 2) NRDC urged DOE to examine the existing data on draw patterns and to conduct its own further testing if necessary. (NRDC, No. 20 at p. 2) AET commented that the draw patterns need to be more realistic in terms of the number of repeated small draws and that it is important for tank-type, instantaneous, and tankless water heaters to all be rated using the same draw patterns for a given capability range, because comparisons among them will otherwise have little meaning. (AET, No. 22 at p. 2) ACEEE commented that the current draw pattern is no longer adequate for generating the information that consumers need to make wise purchasing decisions. In ACEEE's view, the six-draw test does not reflect patterns seen in field studies and that the current six-draw pattern is inadequate, primarily because different technologies that may lead to the same energy use in typical applications would get quite different EF ratings in the lab. (ACEEE, No. 24 at p. 1) Standards Committee 118.2 of ASHRAE submitted minutes from a meeting held on June 28, 2011, indicating that the committee passed motions to develop new draw patterns for a simulated-use test. (ASHRAE, No. 25 at pp. 1-2)

Fifteen commenters supported the implementation of different draw patterns based upon water heater capacities. Bradford White proposed three different draw patterns that would be applicable to water heaters of low use, normal-to-high use, and heavy-duty use. (Bradford White, No. 2 at pp. 5-6; Bradford White, No. 30 at pp. 13-15) PGE and SCE recommended that DOE prescribe draw patterns based on ranges of capacities of units or based upon burner size for tankless units. (PGE, No.

3 at p. 2; SCE, No. 4 at p. 2) Stone Mountain Technologies stated that the flow rate during individual draws and the total volume drawn during the test should be based on the hot water delivery capacity of the model. Furthermore, Stone Mountain Technologies suggested that the capacity should be based on the theoretical volume of hot water that can be delivered in 15 minutes using the energy storage and the net heat input. (Stone Mountain Technologies, No. 5 at p. 2) AHRI and AO Smith recommended that DOE should develop a simulated-use test that will vary for differing models based on some specified criterion such as storage volume or flow rate or other appropriate characteristic. (AHRI, No. 12 at p. 2; AO Smith, No. 8 at p. 2) NEEA indicated that its own laboratory testing and that of some others suggest that multiple draw patterns (perhaps 3 to 5) would be appropriate, depending on the capacity of the water heater. (NEEA, No. 9 at p. 2) NRCan indicated that the CSA P.3 committee is considering 3 or 4 categories for daily hot water use households: Low, medium, high, and, potentially, a point-of-use category. The water heaters would be categorized by first-hour rating, maximum gallons per minute, or maximum heat input. (NRCan, No. 16 at p. 2) General Electric commented that the draw pattern should be proportionately scaled up for large volume water heaters (greater than 50 gallon capacity) and, similarly, scaled down for smaller water heaters (less than 50 gallons). (GE, No. 21 at p. 2) ACEEE stated that DOE must use different draw patterns for water heaters of different capacities and suggested that manufacturers should be allowed to choose how a particular product is rated. (ACEEE, No. 24 at p. 2) In response to the January 2013 RFI, the joint commenters recommended 5 different draw patterns for sizes ranging from point-of-use to very high use household/light commercial. The joint commenters noted work by LBNL and Stone Mountain Technologies in devising a capacity rating based on published storage volume and heat source size. (Joint comment, No. 35 at p. 2) GE commented that water heaters should be tested based on their capacity as measured by the first-hour rating. (GE, No. 36 at p. 1)

AHRI provided a suggested simulated use test that described four different draw patterns that would be applied to a water heater based on its first-hour rating or maximum flow rate measurement. (AHRI, No. 46 at pp. 5-6) As explained below, AHRI suggested cut-offs between the four different size categories at first-hour ratings of 20, 55, and 80 gallons and at maximum flow rates of 1.5, 2.5, and 3.5 gallons per minute; all values correspond to a nominal outlet temperature of 135 °F and a nominal inlet temperature of 58 °F. The draw patterns are based on a set of activities that would be expected in a typical residence, with the total volume removed per day for the four patterns being 15, 40, 64.2, and 82.75 gallons. The draw pattern for point-of-use water heaters involved 11 draws, while the other three draw patterns involved 12 draws each. Flow rates varied for each draw during the draw pattern, except for the point-of-use draw pattern which imposed a fixed flow rate of 1 gallon per minute throughout the test.

Applied Energy Technology acknowledged the need to test a water heater according to a draw pattern appropriate for its delivery capacity, but instead of supporting a suite of tests for water heaters of different capacity, it recommended that DOE consider a test approach applicable to water heaters of all sizes from which pieces of information are obtained pertaining to the particular capacity of the water heater under test. AET's suggested test method entails a series of draw clusters that simulate different end uses in a residence. Water heaters with a high capacity could presumably deliver sufficiently hot water at all times during the test, but water heaters with lower capacity may fail to provide water at a required temperature under those draw clusters that called for large volumes of hot water in a short time. Under AET's approach, a water heater would be rated for those clusters during which it could meet the demand placed upon it as determined by the outlet temperature during those draw clusters. (AET, No. 22 at pp. 18-37) AET commented that details of the test method needed to be refined, and no discussion was provided as to how to use the efficiency determined during each draw cluster for which the water heater could meet the demand to yield an energy factor.

DOE has tentatively concluded that the current DOE test procedure's draw pattern applied during the simulated-use test can potentially yield results that are biased towards particular water-heating technologies. The DOE test procedure specifies a small number of draws per day when compared to typical usage, a relatively large time between draws, and uniform volumes of water per draw. The test procedure applies to all water heater technologies without regard to any inherent differences in performance across the technologies. A revised draw pattern in the simulated-use test that better reflects how water is actually used in different homes using different water heater technologies could allow for a more realistic representation of the expected energy consumption consumers would experience for a particular water heater technology.

A test procedure that is completely uniform across all water heater types and sizes (

i.e.,

no differences in the amount of hot water drawn or the number of draws, etc.) can provide results that are biased toward different water heater technologies. For electric resistance and fossil fuel-fired storage water heaters, the predominant factor affecting the energy factor is the total amount of water removed per day. At a given set point temperature, the water heater loses heat to the environment at an essentially constant rate regardless of the amount of water removed. Since the energy factor is the ratio of hot water energy delivered to the overall energy consumed by the water heater, which is a sum of that needed to heat the water and that which is lost to the environment, the energy factor increases when the numerator of that ratio increases. Hence, the energy factor increases when the amount of water delivered per 24 hours increases. The performance of these water heaters is not expected to depend upon the length of draws, the flow rates of draws, nor the spacing between the draws.

Storage water heaters that rely on heat pump technology show the same efficiency trend with overall delivered water volume per day as seen with other storage water heater technologies, but it is also expected that the energy factors would depend upon the way that water is distributed among draws. A heat pump water heater operates most efficiently when the heat pump portion of the water heater provides the heat to the water as opposed to any backup electric resistance heating. This backup resistance heating is needed when the hot water in the appliance is depleted and a rapid amount of heat needs to be delivered to raise the stored water temperature back to the desired value. Since heat pumps tend to have a low heating rate, heat pump water heaters currently on the market incorporate resistance elements to provide that rapid heating. These resistance elements, however, dramatically reduce the efficiency. In the current test procedure, water heaters that have been tested do not require backup electric resistance heating to maintain an adequate water temperature within the tank since there is enough time between draws for the tank to fully recover to a

temperature that is above that which triggers the resistance elements. If a revised draw pattern would require a larger amount of water to be drawn from the water heater in a set period of time, either through a single larger draw or multiple draws spaced close together as would be more representative of average use, the heat pump water heater may be forced to utilize electric resistance heating to maintain the required tank temperature, and the energy factor would drop.

For small storage water heaters in the “point-of-use” category (water heaters that generally are not intended to serve as a single water heater for all uses in a household), a test utilizing the current draw pattern would likely result in delivery of water during the draws that is below a temperature that would be considered useful by the resident. These units have a small stored volume of hot water that is appropriate for small uses such as hand washing but not for a draw of more than 10 gallons at 3 gallons per minute (gpm), as is imposed by the current test procedure. An efficiency test that takes into account these limitations should put a demand on the water heater that calls for individual draws less than those implemented in the current DOE test.

Draw patterns and water heater cycling frequency likely have an effect on the measured efficiency of instantaneous water heaters. Instantaneous water heaters typically use large burners or heating elements to heat the water from the inlet temperature to the outlet temperature as it flows through the appliance. The burner typically is not energized until a water draw is initiated. Once the draw stops, the burner is shut off, and the remaining water in the appliance and the material making up the appliance gradually lose their heat and return to the ambient temperature. This heat loss (losses associated with heating up and cooling off of the burner) is considered a cycling loss, as the loss is associated with the cycling on and off of the water heater's main energy input.

Draw patterns affect water heater cycling and, thus, the overall measured efficiency of the water heater. Shorter draws typically act to lower the measured efficiency because, as the water heater cycles more frequently, cycling losses increase. Further, cycling losses account for a larger portion of energy usage during shorter draws, resulting in a disproportionate amount of heat input going towards raising the temperature of the heat exchanger as opposed to raising the temperature of the water. Hence, shorter draws typically result in a lower measured efficiency. However, draws that are clustered closer together typically act to raise the measured efficiency by reducing cycling losses because the appliance may be able to maintain an elevated temperature between the end of one draw and the initiation of a subsequent draw. The cycling losses are mitigated by the fact that the appliance does not cool down as much after the end of one draw and thus does not need to be heated as much when the subsequent draw is initiated. Hence, shorter spacing between draws typically results in an increase in the water heater's measured efficiency.

The efficiency of instantaneous water heaters is less affected by the total volume of hot water delivered per day than storage water heaters because their standby losses (i.e., losses associated with a water heater in standby mode, independent of the cycling losses discussed above) are negligible. Standby losses increase measured energy consumption without a corresponding increase in energy delivered, thereby decreasing the energy factor. An increase in the volume of water delivered per day results in a nearly proportional increase in energy consumption for instantaneous water heaters. The other drivers of total energy consumption are standby heat loss and cycling heat loss, with standby heat loss being essentially constant during the test and cycling losses being a function of the number of draws and their spacing. As these two losses approach zero, the dependence of energy factor on daily draw volume decreases since the energy consumption is dominated by that needed to heat the water, which vary proportionally. For water heaters currently on the market, the cycling losses experienced by instantaneous water heaters tend to be much less than the standby losses experienced by storage water heaters. Because standby losses increase measured energy consumption without a corresponding increase in energy delivered, the total energy consumption for instantaneous water heaters is much closer to the energy needed to heat the water than that seen with storage water heaters, and the dependence on daily draw volume is also lower.

The flow rate at which water is drawn from the water heater may affect the measured efficiency of an instantaneous water heater. The heat transfer from the heat exchanger to the water is a function of the speed at which water moves through the heat exchanger; efficiency may increase at higher flow rates. Additionally, since instantaneous water heaters typically employ heating elements or burners with variable capacity to meet the desired outlet temperature at different flow rates, the efficiency of the heat input device (

e.g.,

burner or heating element) may also vary depending upon the heating rate. This effect could either increase or decrease the overall efficiency depending upon the setting to which the heating element or burner is tuned.

To summarize, under the current DOE test procedure, certain types of water heaters can provide results that are biased toward certain water heater technologies. The small number of draws imposed under the existing test procedure, relative to the actual number of draws noted in field usage data, reduces the measured cycling losses relative to those occurring in field conditions. By contrast, the duration of time between draws in the test procedure is relatively long when compared to field usage data, which effectively increases the measured cycling losses relative to those occurring in field conditions. Water heaters with low heating rates would appear to benefit since they could easily recover to operational temperature.

The current DOE test procedure does not adequately measure energy efficiency during a representative average use cycle or period of use for some technologies. The uniform volume taken during each draw of the current test method does not simulate high-demand use, such as a long shower, that could change the way that a water heater operates, nor does it simulate performance under short draws during which water is not delivered at the prescribed set point temperature. Furthermore, DOE agrees with commenters who stated that the draw patterns should be based on the delivery capacity of the water heater because, as explained above, the measured water heater efficiency is influenced by the draw pattern incorporated into the test procedure and because a single draw pattern is not appropriate for the range of water heater sizes that fall under the scope of this test procedure. Consequently, DOE proposes a revised simulated-use test that involves four different draw patterns for water heaters of different capacities. Water heaters would be classified into the following usage categories (described below) corresponding to their usage capacity: (1) Point-of-use; (2) low; (3) medium; and (4) high. The proposed classifications are based on delivery capacity as determined in a first-hour rating test for storage-type water heaters or a maximum flow rate test for instantaneous water heaters.

In crafting a proposed set of draw patterns, DOE considered and utilized

the recommended draw patterns submitted by commenters, in particular those submitted by Bradford White (Bradford White, No. 2 at p. 3; Bradford White, No. 30 at p. 11), AHRI (AHRI, No. 46 at p. 3), and AET (AET, No. 22 at p. 1). (DOE notes that no test data were supplied with any of the proposed test methods.) Additionally, DOE utilized data compiled by the LBNL

that describes field studies of hot water usage to ensure that the draw patterns were representative of field use. LBNL found that typical usage in residences in North America is characterized by a large number of small volume draws, by a smaller volume of water per day than is currently prescribed in the residential test method, and by a significant variation in draw volume and number of draws per day. The data suggest development of a single typical draw pattern would be difficult and inappropriate. Instead, DOE has attempted to develop several draw patterns that capture key features affecting performance (

e.g.,

length and frequency of draws, flow rates), while maintaining a test that will not be overly burdensome to conduct and which will produce repeatable results.

Lutz, JD, Renaldi, Lekov A, Qin Y, and Melody M., “Hot Water Draw Patterns in Single Family Houses: Findings from Field Studies,” Lawrence Berkeley National Laboratory Report number LBNL-4830E (May 2011) (Available at

http://www.escholarship.org/uc/item/2k24v1kj

) (last accessed October 18, 2013).

Based upon this understanding, DOE proposes the following draw patterns containing volumes per day that are consistent with the data found by LBNL. The proposed low-use pattern calls for the water heater to provide 38 gallons per day, which is consistent with the median values found for households with 1 to 2 occupants. The proposed medium-use pattern, which requires a supply of 55 gallons per day, is consistent with the median values found for households with 3 to 4 occupants. The LBNL data show a median volume of hot water used for families with 5 or more occupants to be approximately 58 gallons. This unexpectedly low result might be attributable to the lower sample number of such large households. For this reason, DOE has departed from the LBNL field data and proposes a total volume of 84 gallons per day for the high-use pattern. This value is consistent with that proposed by Bradford White (Bradford White, No. 2 at p. 5) and AHRI (AHRI, No. 46 at p. 6), and DOE believes that it is a representative number for high use cases based on the range of hot water usage per day reported by LBNL. While the LBNL report suggests that the number of draws of hot water per day could exceed 50, DOE has tentatively determined that imposing a draw pattern during a test with that many draws could lead to measurement difficulties owing to (1) the need to measure energy removal in such short draws; and (2) the potential variation inherent in precisely controlling so many draws. Accordingly, DOE has tentatively concluded that a smaller number of draws (ranging from 9 to 14) will strike a balance between the need to capture cycling losses associated with water heater operation and the need for accurate measurement. Additionally, many of the short draws found in field tests are clustered close together in time. In these situations, cycling losses are negligible because the water heater remains at operational temperature over the course of the smaller draws. For these draws, energy efficiency can be reliably estimated by consolidating the multiple draws into a single larger draw.

As discussed in section III.F, “Test Conditions,” DOE proposes that both the first-hour rating test and the maximum flow rate test will be carried out with the prescribed outlet water temperature at 125 °F. DOE proposes to modify the first-hour rating test to stop draws of hot water when the outlet water temperature drops 15 °F below its maximum temperature during each draw. This cut-off temperature is a departure from the current test, which cuts off the draw when the outlet water temperature drops 25 °F below the maximum recorded outlet temperature. With the nominal delivery temperature being 135 °F in the current test procedure, the cut-off temperature is 110 °F. This proposed change in temperature drop to trigger the end of a draw would maintain the approach that the minimum useful temperature of hot water is 110 °F. This value is consistent with Table 3, Chapter 50 of the ASHRAE Handbook of HVAC Applications,

which indicates that a representative temperature for showers and tubs is 110 °F. For water heaters with rated storage volumes at or above 20 gallons, water will continue to be drawn at 3 gallons per minute during the first-hour rating test. For water heaters having rated storage volumes below 20 gallons that are not designed to provide a continuous supply of hot water, water will be drawn at a rate of 1 gallon per minute during the first-hour rating test. A water heater that is designed to provide a continuous supply of hot water at the set point temperature

will be tested to obtain a maximum flow rate, while water heaters that are not so designed will be subject to a first-hour rating test.

ASHRAE 2011,

Handbook of HVAC Applications,

Chapter 50 Service Water Heating (Available at:

https://www.ashrae.org/resources-publications/handbook

A set point temperature is the temperature that the user selects via a thermosat as the temperature of the delivered hot water at the outlet of the water heater.

DOE proposes the following ranges of first-hour ratings and maximum flow rates to characterize storage and instantaneous water heaters, respectively:

Point-of-use:

First-Hour Rating less than 20 gallons.

Maximum Flow Rate less than 1.7 gallons per minute (gpm).

Low:

First-Hour Rating greater than or equal to 20 gallons, less than 55 gallons.

Maximum Flow Rate greater than 1.7 gpm, less than 2.8 gpm.

Medium:

First-Hour Rating greater than or equal to 55 gallons, less than 80 gallons.

Maximum Flow Rate greater than or equal to 2.8 gpm, less than 4 gpm.

High:

First-Hour Rating greater than or equal to 80 gallons.

Maximum Flow Rate greater than or equal to 4 gpm.

DOE based these proposed ranges (or “bins”) on first-hour rating data for existing models, requirements of the current plumbing code, and recommended cut-offs proposed by Bradford White and AHRI. (Bradford White, No. 2 at pp. 4-5; Bradford White, No. 30 at p. 2; AHRI, No. 46 at p. 4) In today's NOPR, DOE proposes to modify the set point temperature from the current 135 °F to 125 °F, as discussed further in section III.F.1. While it is acknowledged that the published first-hour rating data were taken at a set point temperature of 135 °F, limited testing shows that first-hour ratings at a set point temperature of 125 °F are comparable to those at 135 °F. The first-hour ratings of all water heaters on the market cluster around certain values to accommodate different levels of use. Those clusters are captured in the bins proposed here. DOE's proposed bins differ from those presented by Bradford White in its comments on the October 2011 RFI and the January 2013 RFI, because the commenter's approach grouped medium-use and high-use water heaters into a common category and added a category for water heaters meant for so-called “heavy-duty use.” (Bradford White, No. 2 at pp. 4-5) DOE

has tentatively concluded that the categories defined by Bradford White group too many water heaters in the mid-use category. DOE's proposed first-hour rating categories match those proposed by AHRI. DOE believes that these breakpoints are appropriate based on minimum first-hour ratings required by the Uniform Plumbing Code.

The code mandates minimum first-hour ratings for water heaters serving homes with different combinations of bedrooms and bathrooms. Four different minimum values are implemented by the code: 42, 54, 67, and 80 gallons.

International Association of Plumbing and Mechanical Officials, “2012 Uniform Plumbing Code” (2012) (Available at

www.iapmo.org

) (last accessed March 29, 2013).

DOE has tentatively concluded that its proposed usage categories are appropriate, given that they are consistent with the Uniform Plumbing Code, albeit with certain minor modifications. In considering the Uniform Plumbing Code, DOE considered 42 gallons per day as a lower limit for the low-use category, but concluded that it would not be realistic for a water heater intended to provide point-of-use functionality to deliver up to that level of water in one hour. Instead, DOE has tentatively decided to set the upper limit for point-of-use water heaters and the lower limit for low-use water heaters at 20 gallons per day. While water heaters with first-hour ratings below 42 gallons per day may not be used as a single water heater for whole-house applications, DOE believes that their use more closely resembles that of low-use water heaters rather than that of point-of-use water heaters. DOE has grouped homes with 2 to 4 bedrooms and less than 3 bathrooms in the medium category, which would require minimum first-hour ratings of 54 or 67. Five bedroom homes with up to 2.5 bathrooms or homes with three or more bathrooms would require water heaters with first-hour ratings at least 80 gallons per day; these water heaters fit into the proposed high-use category.

DOE acknowledges the uncertainty in using data generated under the existing test procedure, which are based on a first-hour rating test conducted at a delivery temperature of 135 °F, for establishing bins for the applicable draw patterns. Testing by DOE has indicated that storage water heaters with relatively high recovery rates yield higher first-hour ratings under the proposed procedure than under the current procedure, while those with low recovery rates tend to have slightly lower first-hour ratings at 125 °F compared to the rating at 135 °F. DOE seeks comments related to the translation of current first-hour ratings to a first-hour rating determined using the proposed 125 °F set point and the proposed breakpoints between the different size categories. This is identified as issue 2 in section V.E, “Issues on Which DOE Seeks Comment.”

The proposed maximum gpm ratings for instantaneous water heaters were devised based on expected uses for water heaters serving applications of different sizes. The categorizations are consistent with those suggested by AHRI, with the ratings being scaled up to account for the higher maximum flow rates expected at the lower set point temperature (125 °F).

DOE seeks comment on the proposed criteria for characterizing water heaters as point-of-use, low usage, medium usage, and high usage, and whether these criteria are appropriate and sufficient. This is identified as issue 3 in section V.E, “Issues on Which DOE Seeks Comment.”

For each sizing category, DOE proposes to apply a 24-hour simulated-use test to determine the energy factor. One of four separate draw patterns would be applied to each water heater based on the appropriate sizing category. The draw patterns would have the following number of draws per day: Point-of-use: 9; low: 11; medium: 12; and high: 14. DOE acknowledges that the number of draws per day in a typical household can often approach 100 and that the volume in each draw can be very small. However, DOE believes that a test with so many draws would be subject to large variability in results due to the challenges in accurately determining the energy content of such short draws. In contrast, DOE has tentatively concluded that the proposed draw patterns would capture the key ways in which hot water is used in residences while yielding a test that is repeatable.141

DOE's proposal uses a slightly modified version of the draw patterns submitted by Bradford White and AHRI in response to the January 2013 RFI as a basis for the low, medium, and high draw patterns; Bradford White did not submit a draw pattern for point-of-use water heaters. In addition, the patterns presented by Bradford White grouped medium-use water heaters with heavy use, so data were missing for both point-of-use and medium use water heaters. Additionally, information provided by AET has also been considered to craft some aspects of the draw patterns. AET provided information on typical uses that would be applied to a water heater in terms of flow rates, number of draws, and volumes. (AET, No. 22 at pp. 22-36) This information was utilized in drafting the proposed draw patterns for point-of-use and medium-use water heaters.

A number of changes are proposed as compared to the current draw patterns found in the DOE simulated-use test procedure. First, the proposed draw patterns would involve more draws than are currently implemented, and the draws would vary in length during the simulated-use test. Second, the spacing between the draws would vary to better capture the effects of different cycling times on the energy efficiency of the water heater. Third, the proposed draws would involve different flow rates during the test; these flow rates would be 1.0, 1.7, or 3.0 gpm.

The total volumes that would be removed for each category are in line with recent field data compiled by the Lawrence Berkeley National Laboratory that was previously discussed. DOE believes that the proposed draw patterns would improve the estimation of energy efficiency by considering the impact of shorter draws, lower flow rates, higher number of draws, and variable standby times between draws.

For point-of-use models, the flow rate is specified as the lesser of 1 gpm or the maximum gpm. Therefore, if a unit were to have a maximum gpm rating below 1.0 gpm, that unit would be tested at its maximum gpm flow rate.

DOE proposes draw patterns for implementation in the 24-hour simulated-use tests as outlined in Table III.2 through Table III.5. The total volume of water drawn in the proposed draw patterns are 10 gallons for the point-of-use pattern, 38 gallons for the low-usage pattern, 55 gallons for the medium-usage pattern, and 84 gallons for the high-usage pattern.

Table III.2—Point-of-Use Draw Pattern

Draw number

Time during test

(hh:mm)

Volume

(gallons)

Flow rate

(gpm)