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Federal Register / Vol. 86, No. 115 / Thursday, June 17, 2021 / Proposed Rules of the compressor is not necessary to provide sufficient cooling to the space.
Similarly, a multi-capacity compressor can unload individual cylinders within the compressor, which allows the compressor to remain on, but at a reduced capacity, to more closely match the required cooling load.
The current DOE test procedure measures the performance of a walk-in condensing unit while operating under a full cooling load at a fixed capacity;
i.e., the compressor is operated continuously in its on state. See AHRI
12502009, Tables 11 through 14 and Appendix C, section 3.0. While AHRI
12502009 and AHRI 12502020 both include test methods for multiand variable-capacity matched pair refrigeration systems, there is no test method for multiand variable-capacity condensing units when tested alone. As a result, any inefficiencies due to compressor cycling, and any performance benefit associated with part-load operation, are not captured during the DOE test. Consequently, the current test procedure may underestimate the efficiency benefits of multiand variable-capacity systems.
DOE is aware of some multior variablecapacity condensing units that are currently available on the market.38
Issue 42: DOE requests input on the development of test methods that would more accurately measure the energy use performanceincluding accounting for the potential efficiency benefits of multiand variable-capacity systems both for matched-pair and stand-alone condensing unit testing. DOE seeks data and information showing the potential magnitude of energy savings by reducing cycling losses in these multi and variable-capacity systems. DOE
requests market information on whether there are multiand variable-capacity condensing units available on the market in addition to those already identified and the brand names and model numbers of those additional units.

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7. Systems for High-Temperature Freezer Applications In the June 2014 ECS final rule, DOE
established equipment classes for mediumand low-temperature walk-in refrigeration systems. 79 FR 32050, 3206932070. While the terms medium-temperature and lowtemperature are not explicitly defined, the June 2014 ECS final rule, 2015
ASRAC negotiations, December 2016 TP
38 Multi-capacity product information from one manufacturer can be found at http
www.regulations.gov Docket No. EERE2017BT
TP00100004.

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final rule, and July 2017 ECS final rule all consistently used the term mediumtemperature to refer to walk-in cooler/
refrigerator refrigeration systems and the term low-temperature to refer to walkin freezer refrigeration systems.
The current test procedure for walkin refrigeration systems specifies rating conditions of 35 F for refrigerator systems and 10 F for freezer systems see section 5 of AHRI 12502009, incorporated by reference at 10 CFR
431.303b. The 35 F and 10 F
rating conditions produce a metric, AWEF, which is generally representative of the mediumand lowtemperature refrigeration systems energy use when installed in walk-in coolers and freezers, respectively. The AWEF metric forms the basis for energy conservation standards for mediumand low-temperature refrigeration systems.
However, field usage data indicate that walk-in refrigeration systems operate at a broad range of application temperatures both above and below the respective 35 F and 10 F rating points.
As discussed in the December 2016
TP final rule, stakeholders commented that so-called high-temperature freezer walk-ins, which have an enclosed storage i.e. room temperature range of 10 F to 32 F, are refrigerated with medium-temperature condensing units. 81 FR 95758, 95790. Under the statutory definitions of walk-in cooler and walk-in freezer, this equipment would be considered a walk-in freezer because its room temperature is less than or equal to 32 F 42 U.S.C.
631120. Accordingly, these refrigeration systems would be tested using a room temperature of10 F, as specified in Appendix C. However, stakeholders commented as to the difficulty these medium-temperature refrigeration systems have in meeting this temperature condition when using lower GWP refrigerants.39 81 FR 95758, 95790. Lennox offered data suggesting that medium-temperature units generally perform more efficiently at the 10 F operating condition i.e., the low end of the cited high-temperature freezer temperature range than lowtemperature systems. Docket EERE
2015BTSTD0016, Lennox, No. 89 40
39 Lennox commented that the industry was moving to low-GWP refrigerants in response to the Environmental Protection Agency final rule under the Significant New Alternatives Policy SNAP
program that prohibited the use of R404A in certain retail food refrigeration applications, including WICF refrigeration systems starting July 20, 2016. Docket EERE2016BTTP0030, Lennox, No. 13 at p. 2 For further discussion of the SNAP rule, see section II.E.8 of this document.
40 Available at https www.regulations.gov/
document?D=EERE-2015-BT-STD-0016-0089.

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at pp. 25 Lennox suggested that this high-temperature freezer application may justifiably represent a third class of walk-in refrigeration systems, but also noted the reporting and testing burden that establishing an additional set of classes would incur. In response, DOE
noted that manufacturers of equipment that cannot be tested in a way that properly represents their performance characteristics may petition DOE for test procedure waivers, as detailed in 10
CFR 431.401. DOE also indicated that it may consider amending its regulations by establishing new equipment classes and applicable test methods. 81 FR
95758, 9579095791.
DOE is currently considering how, if at all, to address high-temperature freezer walk-ins, including whether to establish test procedure provisions to specifically address the refrigeration systems serving such equipment.
Multiple approaches are under consideration. One approach would allow walk-in manufacturers and contractors to install a medium temperature refrigeration system that is tested and certified based on the standardized 35 F walk-in cooler temperature or corresponding refrigerant suction conditions as a walk-in freezer, if the walk-in refrigeration system is marketed at or above 10 F. By extension, the approach would also allow representations of performance e.g. capacity, power input of such medium-temperature refrigeration systems for walk-in temperatures at 10 F and higher without requiring them to be tested and certified based on the10 F lowtemperature walk-in test condition. This approach would alleviate the need for a new high-temperature freezer equipment class thus avoiding the associated certification test burden, while still allowing the potentially more efficient medium temperature refrigeration systems to be used for high temperature freezer applications.
Docket EERE2015BTSTD0016, Lennox, No. 89 at pp. 25 offering data suggesting that medium temperature units generally perform more efficiently at the 10 F operating condition than low-temperature systems.
DOE could establish new definitions for the terms low-temperature refrigeration system and mediumtemperature refrigeration system, that implement this potential structure. For example, low-temperature refrigeration system could be defined as a refrigeration system used to cool the interior of walk-in freezers and maintain a refrigerated room temperature of 10 F
or less, while medium-temperature refrigeration system could be defined
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