On and after November 27, 2023, any representations made with respect to the energy use or efficiency of all pool heaters must be made in accordance with the results of testing pursuant to this appendix. Until November 27, 2023, manufacturers must test gas-fired pool heaters in accordance with this appendix, or appendix P as it appeared at 10 CFR part 430, subpart B revised as of January 1, 2021. Prior to November 27, 2023, if a manufacturer makes representations of standby mode and off mode energy consumption, then testing must also include the provisions of this appendix, or appendix P as it appeared at 10 CFR part 430, subpart B revised as of January 1, 2021, related to standby mode and off mode energy consumption.