Performance Testing of a Residential Motorless Air Exchanger System

A heat recovery ventilator (HRV) is used to create a balanced ventilation system in residential buildings and as an energy-saving measure. HRVs bring in outside air which is tempered with outgoing stale air, with only the small energy penalty of the blower power to overcome the pressure drop in the HRV. HRVs have been used in cold climates and have often performed poorly due to frosting failure. HRVs require de-icing in cold climate application, where the exhaust warm air is periodically recirculated during defrost cycles, interrupting the flow of the exhausting air and redirecting the stale warm air back into the house, to defrost the HRV core. This study was performed to assess the performance of a motorless air exchanger (MAE), in comparison to a conventional motorized HRV, and determine if it could perform in winter without frosting failure. The parameters that were compared for this study include sensible effectiveness, defrost occurrence and energy consumption. The air exchanger system showed higher sensible effectiveness and no “defrost cycles” were required. Operation of the air exchanger system resulted in a slight increase (~2.8%) in whole house energy consumption in winter and showed savings of ~11.2% in summer.