Three-Stage HRV Evaluation
In Alaska and Canada, the main defrost strategies for heat recovery ventilators (HRVs) involve recirculating return air across the heat exchanger core and back into the supply air for the house. In cold climates, this type of frost protection system can undermine ventilation standards. To overcome this issue, continuous ventilation systems such as the Zehnder HRV provide frost protection by preheating air before it enters the HRV core, resulting in increased supply air temperatures and preventing the heat exchanger core from freezing. This paper discusses the effectiveness of various frost protection strategies, the energy use of the system, and the effect of continuous ventilation on indoor air quality in a cold climate home.
The full technical report is available here.