The XHX series heat recovery ventilator (HRV) can help make mechanical ventilation more cost effective by reclaiming energy from exhaust airflows. XHX series use heat exchangers to heat or cool incoming fresh air, recapturing 60 to 80 percent of the conditioned temperatures that would otherwise be lost. The heat recovery unit is the heart of a HRV, consisting of a cross flow air-to-air aluminum heat exchanger. Incoming and outgoing airflows pass through different sides of the exchanger (but are not mixed), allowing conditioned exhaust air to raise or lower the temperature of incoming fresh air.
After passing through the heat recovery unit, the warmed or cooled fresh air goes through the HVAC air handler, or may be sent directly to various rooms. Stale air from return ducts pre-conditions the incoming flow before exiting. Systems in various sizes and configurations are available to automatically maintain 0.35 air changes per hour, the rate usually recommended to maintain good air quality. The system includes filters to further control contaminants that would otherwise re-circulate through the home.
Conventional fan and vent assemblies for bathrooms and kitchens, often required by code, may allow significant energy losses. A HRV system can incorporate small, separately switched booster fans in these rooms to control moisture or heat generated by activities like showering or cooking. Odors and pollutants can be quickly removed, but energy used to condition the air is recycled in the heat recovery unit.