R405.7.7 Installation Criteria for Homes Claiming the Heat Recovery Unit (HRU) Option

The heat recovery unit option may be used for installation of a waste heat recovery unit (HRU) on either an air conditioner or a heat pump where the heat recovery unit has a minimum net useful heat exchange effect of 50 percent and meets the following criteria:

1. The net useful heat exchange effect shall be demonstrated by either a Form R400D-2020 prominently displayed on the unit with test results clearly visible for inspection or by an ARDM-certified refrigerant desuperheater seal affixed to the unit.
2. The net useful heat exchange effect shall have been determined by an independent laboratory testing to AHRI Standard 470.
3. If more than one air-conditioning system is installed in a residence and only one HRU is installed, energy load shall be based on the gallon capacity of the water heater to which it is coupled and the total capacity of the water heaters in the residence. In such case, the HRU shall be attached to the system serving the daytime primary living areas (family room, living room, kitchen, dining room and adjacent bedrooms and bathrooms).