HRVs

HRVs, or heat recovery ventilators, are mechanical ventilation devices that exchange indoor air with outdoor air while transferring heat between the two streams. By reclaiming heat from exhausted air, they preheat incoming air, reducing heating needs in cold climates and helping maintain indoor air quality with fresh air exchange.

Operation typically uses a counterflow or crossflow core through which two separate airstreams pass without mixing. A heat exchanger—commonly plate-type or a rotary wheel—transfers sensible heat from the departing air to the incoming air. Most systems include two dedicated fans and ductwork that balances airflow to prevent pressure differences.

HRVs differ from energy recovery ventilators (ERVs). HRVs focus on sensible heat recovery and are preferred in colder climates, while ERVs also transfer some latent heat and humidity, which can help in humid or mixed climates. The choice depends on climate, airtightness, and humidity control needs.

Installation requires appropriate sizing, duct routing, and balance to ensure effective ventilation without over-pressurizing spaces. Maintenance involves periodic filter replacement, cleaning the core or wheel, and checking seals and dampers. Standards and codes, such as ASHRAE 62.2 in the United States or regional equivalents, guide ventilation design and energy performance.