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Federal Register / Vol. 86, No. 127 / Wednesday, July 7, 2021 / Proposed Rules
the air collected during the dehumidification test and uses it to calculate a secondary measure of MRC.
This secondary measure of MRC is then compared to the primary MRC
measurement, which is based on supply and outdoor ventilation airflow and air condition measurements.
AHRI 9202020 requires this secondary measure of MRC for all dehumidification tests, and comparison to the primary measure of MRC at Standard Rating Condition A. This requirement is for all DDXDOAS units that: a Do not use condensate collected from the dehumidification coil to enhance condenser cooling or include a secondary dehumidification process for which the moisture removed from the supply air stream is not collectable in liquid form, and b either are not equipped with VERS or are equipped with VERS and tested using Option 2
see section C5.1 of AHRI 9202020.
AHRI 9202020 does not require a secondary dehumidification capacity measurement for DDXDOAS units equipped with VERS that are tested using Option 1. DOE understands that this is because: a No viable method has been developed and validated that appropriately accounts for the water vapor that transfers between air streams of an energy recovery wheel, and b the test burden of accounting for moisture in the exhaust air stream would be excessive. DOE is proposing to adopt the secondary capacity test measurements specified in AHRI 920
2020 section C5.1 Dehumidification Capacity Verification, as enumerated in section 2.2.1f of the proposed Appendix B, including the cooling condensate secondary test measurement discussed previously.
For DDXDOAS units with energy recovery tested using Option 2, as discussed in section III.B.3.h of this NOPR, the test is conducted by setting the conditions of the air entering the unit at both the outdoor air inlet and return air inlet to simulate the conditions that would be provided by the energy recovery device in operation.
As a result, the moisture removal in dehumidification mode or heating in heating mode for heat pump DDX
DOAS measured during the Option 2
primary and secondary capacity tests reflects only the moisture removed or heating by the conditioning coil. The MRC or qhp for the DDXDOAS is calculated by adjusting the measured moisture removal or heating for the primary test to account for the total moisture removal or heating by the energy recovery device and the conditioning coil. Because the moisture removal or heating capacity measured
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for the primary and secondary tests are based on the simulated test conditions, sections 6.9 and 6.10 of AHRI 9202020
use these measured values for the secondary capacity verification under Option 2. DOE is proposing to adopt these requirements specified in AHRI
9202020 section 6.9 Moisture Removal Efficiency Ratings and section 6.10
Heating Capacity, as enumerated in section 2.2.1c of the proposed Appendix B.
a. Corrections In addition to substantive changes, AHRI 9202020 also provides minor corrections to instructions in ANSI/
AHRI 9202015. However, in its review of AHRI 9202020, DOE identified an error and an omission in the latest industry test procedure. Specifically, DOE notes that section 6.9.2 of AHRI
9202020 provides erroneous instruction for the calculation of the degradation coefficient, and sections 6.1.5.2.3 and 6.1.5.2.4 of AHRI 920
2020 refer to the term non-standard low-static motor without providing a definition or explanation of this term.
DOE proposes to correct the calculation instruction and define the term nonstandard low-static motor, as discussed further in the following paragraphs.
DOE also notes a correction made by AHRI 9202020 to address an error in the calculation of supplementary heat penalty in ANSI/AHRI 9202015.
i. Calculation of the Degradation Coefficient As mentioned in section III.B.3.d.v of this NOPR, AHRI 9202020 includes provisions for cases where the unit provides excess dehumidification or heating capacity when operating at its lowest-capacity compressor stage. A
degradation coefficient is applied to the MRE and MRE70 when the supply air dew point temperature measured when operating the unit at its lowest-capacity compressor stage is lower than the target supply air dew point temperature in excess of the specified test condition tolerance. This degradation coefficient accounts for the re-evaporation of condensate which occurs during cycling operation i.e., when the compressor cycles on and off to achieve the target supply air dew point temperature. DOE
understands that the degradation is more pronounced for DDXDOASes equipped with VERS for latent energy recovery or total energy recovery, and, thus, the degradation coefficient should be greater for DDXDOASes operating total energy recovery VERS. Equation 20
in section 6.9.2 of AHRI 9202020
appears to incorrectly attribute the lower degradation coefficient to DDX

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DOASes operating with VERS. As such, DOE has initially determined, supported by clear and convincing evidence, that absent a correction, the degradation coefficient as applied in AHRI 9202020
would not meet the statutory requirements of 42 U.S.C. 6314a23
because it would not produce representative results. DOE proposes to correct Equation 20 by specifying that it is to be used for DDXDOASes without VERS, with deactivated VERS see section 5.4.3 of AHRI 9202020, or with sensible-only VERS tested under Standard Rating Conditions other than D emphasis added because DDX
DOASes with total energy recovery VERS or with sensible-only VERS tested under Standard Rating Condition D are considered separately in Equation 21, which calculates a greater degradation coefficient. This correction would be implemented in section 2.2.1ciii of proposed Appendix B.
ii. Non-Standard Low-Static Motor As mentioned in section III.B.3.d.i of this NOPR, section 6.1.5 of AHRI 920
2020 includes instructions for setting the supply airflow rate for testing. In particular, sections 6.1.5.2.1 through 6.1.5.2.5 of AHRI 9202020 provide directions for adjusting the fans should an initial attempt at setting the airflow be unsuccessful.
Section 6.1.5.2.3 of AHRI 9202020
specifies that if a fans maximum speed is too low to satisfy the airflow and external static pressure requirements within tolerance i.e., the motor speed is at the highest setting, a larger compatible off-the-shelf sheave is not available, or increased speed would overload the motor or motor drive and the motor is not a non-standard lowstatic motor, the tests are to be conducted at the fans maximum speed with the external static pressure satisfying the requirements in Table 7.
However, if the motor is a nonstandard low-static motor, section 6.1.5.2.4 of AHRI 9202020 specifies that the maximum available speed should be used but the supply and return airflow rates should satisfy aforementioned tolerance requirements implying that the external static pressure requirements in Table 7 need not be met. AHRI 9202020 does not define non-standard low-static motor in order to determine which of the two methods is appropriate. Without a definition of non-standard low-static motor, manufacturers may not apply the maximum speed provisions consistently, and the potential for variation risks results that do not reflect the equipments representative average energy efficiency or energy use. As
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