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Federal Register / Vol. 86, No. 127 / Wednesday, July 7, 2021 / Proposed Rules
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appropriate amount of heat to the conditioned space.
Section 6.3 of Appendix AA requires modular blowers to be tested with the electric resistance heat kit with the largest volume of retail sales with that basic model of modular blower. Section 6.6 of Appendix AA also includes provisions for electric furnaces that use electric resistance heat elements. With an electric resistance heat kit, some modular blowers and electric furnaces shut off the electric resistance heat elements beyond certain ESP limits.
These ESP limits may be lower than the ESP levels required by Appendix AA.
As a result, the resistance heat elements would not be energized during testing, making it impossible to complete a test that reflects the electrical energy consumption of the electric heating elements as required in section 8.6.3 of Appendix AA. Since these elements would be energized during typical field use, the test procedure may not produce results that measure energy efficiency during a representative average use cycle.
Issue 16: DOE requests comment on the prevalence of electric resistance heating kits installed in modular blowers and electric furnaces that have cutoff limits based on ESP.
Issue 17: DOE requests comment on the typical range of ESP values at which electric resistance heat kits will automatically shut off.
Issue 18: DOE requests data on the ESP ranges that this equipment experiences in the field and the frequency with which electric resistance heat kits are turned off during actual operation of modular blowers and electric furnaces.
5. Updates to Industry Standards and Consensus-Based Test Procedures In general, DOE will adopt industry test standards as DOE test procedures for covered equipment, unless such methodology would be unduly burdensome to conduct or would not produce test results that reflect the energy efficiency, energy use, water use as specified in EPCA or estimated operating costs of that equipment during a representative average use cycle.
Section 8c of appendix A to subpart C
of 10 CFR part 430.
The current DOE test procedure for furnace fans incorporates by reference ANSI/ASHRAE 1032007. ANSI/
ASHRAE 1032007 is a test procedure for residential furnaces and boilers, rather than a specific test procedure for furnace fans, and calculates AFUE, rather than FER. Therefore, DOEs test procedure for furnace fans in Appendix AA includes references to only certain
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sections of ANSI/ASHRAE 1032007, including requirements for instrumentation and test apparatus setup as well as test methodology.
Appendix AA also includes additional instructions for conducting the FER test, including instructions for calculating FER.
In July 2017, ASHRAE published an update to ASHRAE 103, i.e., ANSI/
ASHRAE 1032017. The 2017 version made several editorial changes to the 2007 version, including use of mandatory language and use of the International System of units. In addition to these editorial changes, the 2017 revision made updates to the test duct and plenum figure Figure 2 of ANSI/ASHRAE 1032017 and the system number table Table 6 of ANSI/
ASHRAE 1032017, and removed figures for surface heat transfer and coefficient of radiation Figures 12 and 13 of ANSI/ASHRAE 1032007. It also adopted an amendment made by DOE in a July 10, 2013 final rule that modified the residential furnace and boiler test procedure to provide a means to accurately calculate AFUE for two-stage and modulating condensing furnace and boiler models meeting the criteria in section 9.10 of ANSI/ASHRAE 103
1993 the version incorporated by reference at the time of the 2013 final rule. 78 FR 41265, 41268.
Figure 2 of ANSI/ASHRAE 1032017
was changed to reflect an extension of the minimum length of the inlet duct from 12 inches to 18 inches. The current DOE test procedure requires that ESP
taps be placed a minimum of 12 inches from the product inlet, indicating that models installed with a return inlet air duct must have a duct length greater than 12 inches. Section 6.4.1, Appendix AA. In practice, DOE does not expect this change to interfere with nor impact the performance rating of consumer furnace fans, because the external static pressure and airflow will not change with this alteration. Additional notes were also added to Figure 2 to clarify inlet duct construction and pressure measurement.
Issue 19: DOE seeks comment on any additional changes not discussed above made in the 2017 version of ANSI/ASHRAE 103 as compared to 2007 version currently incorporated by reference in the DOE test procedure for furnace fans.
Issue 20: DOE requests comment on whether to update the referenced version of ANSI/ASHRAE 103 to the 2017 version and if so, what impacts would that have on the test procedure and test procedure results.
Issue 21: DOE seeks comment on whether its assumption that increasing
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the minimum inlet duct length from 12
inches to 18 inches will not impact the performance rating is correct and, if not, how this duct length change would change the rating.
Issue 22: DOE seeks comment on the availability of consensus-based test procedures for measuring the energy use of furnace fans that could be adopted without modification and more accurately or fully comply with the requirement that the test procedure produces results that measure energy use during a representative average use cycle for the product, and not be unduly burdensome to conduct.
6. Tolerance on Temperature Measuring Instruments Section 5.1 of Appendix AA, which references Section 5.1 of ASHRAE 37
2009, requires that temperature measuring instruments must be accurate to within 0.75 F. Section 6 of Appendix AA references section 7 of ASHRAE
1032007 for the test apparatus setup.
Section 7.6 of ASHRAE 1032007
includes instructions to take temperature measurements with thermocouple grids constructed of either 5, 9, or 17 thermocouples, depending on the stack diameter. The measurement accuracy of a thermocouple grid depends on the type and number of thermocouples used, as well as the magnitude of the air temperature being measured. Using the types of thermocouples commonly used in test facilities including T-type and K-type, the measurement accuracy required in Appendix AA is achievable with a minimum of 5 thermocouples at temperatures up to approximately 450 F.4 Stack temperatures in gas-fired furnaces are unlikely to exceed this temperature. However, DOE has observed some oil-fired furnaces with stack temperatures exceeding 500 F.
DOE is considering whether additional specifications are required to accommodate the measurement of stack temperatures of oil-fired furnaces to ensure the repeatability and reproducibility of FER calculations.
Issue 23: DOE seeks comment on the number and types of thermocouples, or other temperature measurement devices, that laboratories use to measure the stack temperatures of oil-fired furnaces.
Issue 24: DOE requests comment on whether stack temperatures of gas-fired 4 Achievement of the measurement accuracy requirement was calculated using the thermocouple characteristics found in Table 1 of ANSI/ASTM
E230/E230M17 and assuming that the overall measurement accuracy is equal to the measurement tolerance of individual thermocouples of that type divided by the square root of n, where n is the number of thermocouples.

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