System Builder Help

Main	>	What are the defrost modes?
CHOICE OF DEFROST MODE: The defrost mode activates when the temperature of incoming air is below 23 deg F (-5 deg C). Two types are available: HRV without recirculation - Features an automatic timed supply fan "shutdown". HRV with recirculation uses a motorized damper to temporarily block incoming fresh air allowing the warm air from the house to circulate through the HRV. - Maintains equal house pressure. - Does not introduce household odors back into the home. - Provides positive shutoff of supply air when unit is in standby mode.
Courtesy of Fantech 2004