HRV & ERV Systems near you

Both types bring in outdoor air and exhaust stale air in the same way; the difference is in the core. An HRV transfers heat between the two airstreams, while Natural Resources Canada describes an ERV as a type of HRV that can exchange both heat and moisture. In warm, humid weather, an ERV gives you more control by keeping some of the outdoor moisture out of the house.

The right choice depends on how many people live in the home, how much moisture it produces, whether it tends to be too dry or too damp in winter, and the local climate. There's no universal answer, so ask a qualified ventilation contractor to size and recommend the unit, and look for an ENERGY STAR certified model, which Natural Resources Canada says uses less energy, on average, than a standard one.

A tight house without enough fresh air tends to show it, and so does an HRV or ERV that has been switched off, left with clogged filters or never balanced. Natural Resources Canada advises never turning an HRV or ERV off except for servicing, since it is designed to run all the time.

Natural Resources Canada says routine maintenance is usually within a homeowner's reach: cleaning the filters and the core and checking components as the service manual describes. CMHC suggests cleaning or replacing HRV filters every two months, and Natural Resources Canada's ENERGY STAR guidance gives a range of one to three months, so your own manual sets the exact schedule. Turn the unit off and unplug it before opening the access door.

Balancing means adjusting the unit so it brings in about as much air as it exhausts. The technician measures the airflow in the fresh-air and stale-air ducts with instruments, then sets the dampers and fan speeds to match the design. An unbalanced unit can push humid indoor air into the walls and attic, or put the house under negative pressure, which draws in cold drafts and can interfere with the venting of fuel-burning appliances such as a furnace, a water heater or a fireplace.

Balancing belongs at installation and commissioning, and again after changes to the ductwork, a new furnace or a major renovation. Keep the balancing report with the manual, since it records the airflows the next technician should expect to find.

Health Canada recommends keeping indoor relative humidity between 30% and 50%, and a simple hygrometer shows where your home stands. In the heating season, an HRV removes moisture along with stale air, which helps a house that suffers from window condensation. In a small or lightly occupied home during a cold snap, the same effect can make the air too dry. Many controls offer several speeds or a humidity setting, so adjust those within the manufacturer's guidance rather than switching the unit off. An ERV keeps part of the indoor moisture, one reason some homes that run dry in winter use one.

In very cold weather the unit runs a defrost cycle from time to time to keep the core from freezing, which is normal. Ice building up inside the cabinet, in the drain or on the exterior hoods is not, and calls for a service visit.

Renovations that add insulation, new windows or air sealing make a house tighter, which makes them the right moment to plan mechanical ventilation instead of treating it as an afterthought. Natural Resources Canada suggests consulting a local accredited HVAC contractor to choose the right system, and an energy advisor can also help assess how much fresh air the home needs and where the unit, ducts and hoods can go.