HRV vs. ERV: which recovery ventilator a Canadian home needs
What a recovery ventilator does
A recovery ventilator runs two air streams at the same time: it pulls stale air out of kitchens, bathrooms and laundry areas, and draws an equal amount of fresh outdoor air in. The two streams pass through a shared core where heat — and in some designs moisture — moves from one stream to the other without the air itself mixing.
The point is to ventilate without throwing away the energy already spent heating the house. In a cold-climate winter, exhausting warm indoor air straight outdoors and replacing it with frigid outdoor air would be expensive. A recovery core captures much of that warmth on the way out.
Inside the core
Most residential units use a fixed-plate or rotary core. Thin channels keep the supply and exhaust streams separated by a wall that conducts heat. In a counter-current layout, the streams flow in opposite directions, which improves how much heat can be exchanged across the core.
The recovered heat never fully matches the heat in the exhaust stream, so the supply air still arrives cooler than room temperature. In most homes the furnace or heat pump makes up the small remaining difference.
The HRV / ERV difference
The practical distinction is moisture. A heat-recovery ventilator (HRV) transfers heat but keeps the two air streams' moisture separate. An energy-recovery ventilator (ERV) uses a core that also lets some water vapour pass between streams, so a portion of indoor humidity is retained in winter rather than expelled.
- HRV: moves heat only. In a cold, dry winter this can leave indoor air quite dry.
- ERV: moves heat and some moisture. It moderates how dry the air gets in winter and can limit how much outdoor humidity enters in summer.
Neither one is a humidifier or a dehumidifier
An ERV only transfers a share of the moisture already present between the two streams. It does not add or remove water on its own the way a dedicated humidifier or dehumidifier does.
Choosing for a Canadian climate
There is no single right answer across the country, because conditions differ between, for example, a dry prairie winter and a humid coastal summer. A few general considerations apply:
- Homes that already struggle with very dry winter air often lean toward an ERV, which helps retain indoor moisture.
- Homes with high indoor moisture loads — many occupants, frequent cooking, indoor drying — may prefer an HRV's tendency to remove humidity.
- Local building requirements and the advice of a licensed contractor familiar with your region should take priority over any general guidance.
For program details and regional guidance, Natural Resources Canada publishes homeowner-facing material on home energy and ventilation.
Airflow and balancing
A recovery ventilator only works well when its supply and exhaust flows are balanced and set to an appropriate rate for the home. An unbalanced system can pressurize or depressurize the house, which affects comfort and can interfere with combustion appliances. Balancing is normally done at commissioning by a qualified installer using measured airflow, not by guesswork.