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Federal Register / Vol. 86, No. 127 / Wednesday, July 7, 2021 / Proposed Rules
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DOE is proposing that a basic model for a DDXDOAS means all units manufactured by one manufacturer within a single equipment class; with the same or comparably performing compressors, heat exchangers, ventilation energy recovery systems if present, and air moving systems, and with a common nominal moisture removal capacity. This proposed definition of a basic model of a DDX
DOAS would be included in the regulatory text in 10 CFR 431.92.
Issue9: DOE seeks comment on the proposed definition of basic model of a DDXDOAS.
b. Sampling Plan Requirements DOE is proposing sampling requirements to determine the represented values for DDXDOAS i.e., dehumidification and heating efficiencies and MRC. More specifically, by proposing to define at 10 CFR 431.92 DDXDOAS as a subset of DXDOAS, and to define DXDOAS
as a category of small, large, or very large commercial package air conditioning and heating equipment, the proposal would apply the same sampling requirements to DDXDOASes as applicable to other commercial package air conditioning and heating equipment under 10 CFR 429.43, Commercial heating, ventilating, air conditioning HVAC equipment.
In response to DOEs request for general comment on issues associated with adopting the industry test procedures for certain commercial package air conditioning and heat pump equipment in the July 2017 ASHRAE TP
RFI 82 FR 34427, 34445 July 25, 2017, Lennox recommended that DOE
harmonize the certification criteria for commercial HVAC equipment in 10 CFR
429.43 with those for central air conditioners, a consumer product, in 10
CFR 429.16. In particular, Lennox stated that commercial equipment currently has a more stringent confidence limit of 95 percent, but the commenter argued that current testing technology does not support this level of precision. Lennox, No. 8 at p. 6 As DOE is proposing to apply the sampling requirements of 10
CFR 431.43 to DDXDOASes, Lennoxs comment regarding the confidence limit for represented values of energy efficiency, energy consumption, and capacity is relevant to DDXDOASes.
Other manufacturers did not raise concerns regarding the confidence limit required for sampling more typical commercial package air conditioning and heat pump equipment, and Lennox has not provided data regarding variability of units in production and testing. Absent more specific
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information or data regarding the stringency of the confidence level, DOE
is not proposing a change.33
Issue10: DOE requests comment on the sampling plan proposed for DDX
DOASes. DOE specifically requests information and data regarding the proposed confidence level and whether variability of testing of DDXDOASes would require a less stringent level, and if so, what that level should be.
c. Multiple Refrigerants DOE recognizes that some commercial package air conditioning and heating equipment may be sold with more than one refrigerant option e.g., R410A or R407C. Typically, manufacturers specify a single refrigerant in their literature for each unique model, but in its review, DOE has identified at least one commercial package air conditioning and heating equipment manufacturer that provides two refrigerant options under the same model number. The refrigerant chosen by the customer in the field installation may impact the energy efficiency of a unit. For this reason, DOE is proposing representation requirements specific for models approved for use with multiple refrigerants.
Use of a refrigerant that requires different hardware such as R407C as compared to R410A would represent a different basic model, and according to the current CFR, separate representations of energy efficiency are required for each basic model. On the other hand, some refrigerants such as R422D and R427A would not require different hardware, and a manufacturer may consider them to be the same basic model. In the latter case of multiple refrigerant options, DOE proposes to add a new paragraph at 10 CFR
429.43a3 specifying that a manufacturer must determine the represented values for that basic model based on the refrigerantsamong all refrigerants listed on the units nameplatethat result in the lowest ISMRE2 and ISCOP2 efficiencies, respectively. For example, the dehumidification performance metric ISMRE2 must be based on the refrigerant yielding the lowest ISMRE2, and the heating performance metric ISCOP2 if the unit is a heat pump DDXDOAS must be based on the 33 DOE notes that it has previously requested data regarding the variability of units of small, large, and very large air-cooled commercial package air conditioning and heating equipment in production and testing to enable DOE to review and make any necessary adjustments to the specified confidence levels. See 80 FR 79655, 79659 Dec. 23, 2015.
However, DOE did not receive any relevant data in response to that request.

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refrigerant yielding the lowest ISCOP2.
These represented values would apply to the basic model for all refrigerants specified by the manufacturer as appropriate for use, regardless of which one may actually be used in the field, where only one set of values is reported.
DOE notes that this proposal reflects the proposed definition of basic model for DDXDOASes as discussed in section III.B.4.a of this NOPR. Units within a basic model of DDXDOAS
must have the same or comparably performing compressors, heat exchangers, ventilation energy recovery systems if present, and air moving systems, and with a common nominal moisture removal capacity.
Issue11: DOE requests comment on its proposal regarding representations for models approved for use with multiple refrigerants.
d. Alternative Energy-Efficiency Determination Methods DOE proposes to allow DDXDOAS
manufacturers to use alternative energyefficiency determination methods AEDMs for determining the ISMRE2
and ISCOP2 if applicable in accordance with 10 CFR 429.70. By proposing to define at 10 CFR 431.92
DDXDOAS as a subset of DXDOAS, and to define DXDOAS as a category of small, large, or very large commercial package air conditioning and heating equipment, the provisions of 10 CFR
429.43 authorizing use of an AEDM for commercial HVAC equipment would apply to DDXDOAS. DOE notes that the proposed requirements for use of AEDMs to determine DDXDOAS
represented values are consistent with AEDM requirements for all other categories of commercial package airconditioning and heating equipment.
DOE proposes to create four validation classes of DDXDOASes within the Validation classes table at 10
CFR 429.70c2iv: Air-cooled/airsource and water-cooled/water-source, each with and without VERS. The separation into air-cooled/air-source and water-cooled/water source validation classes is the same approach used for other categories of commercial package air-conditioning and heating equipment. For DDXDOASes, the additional class separation by presence of energy recovery reflects ASHRAE
Standard 90.1 delineating equipment classes, in part, based on the presence of VERS and the significant differences in the test methods required with energy recovery. These differences in the test procedures include the potential need for a third test chamber for the Option 1 approach for testing DDXDOASes with energy recovery, and the
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