June 4, 2017

Your home’s lungs – HRV or ERV unit

HRV (Heat Recovery Ventilator) or ERV (Energy Recovery Ventilator) is an equipment found in newer homes.

As new and existing homes become increasingly more airtight, the need for fresh air can be attained by installing an ERV or HRV. Not only will it bring in the fresh air, but it will also eliminate many of the pollutants in your home and recover the heat/cooling from the indoor air as it exits your home. They also help improve indoor air quality. ERVs can also transfer moisture and so affect indoor humidity.




Tight construction helps save energy, but it can also make your air stale and stuffy. Attached garages can contain contaminants such as car fumes that can seep into your home. Spray-Foam insulation helps keep your home warm, but it also means indoor air is continually recirculated.

No matter how careful you are, there will always be some pollutants in your home and, therefore, a need for ventilation. Additional information on indoor air quality is available from the Canada Mortgage and Housing Corporation’s Canadian Housing Information Centre.

Components of an HRV or ERVsystem:

An HRV system consists of the following equipment:

• insulated ducts for incoming (fresh) and outgoing (stale) air, with exterior hoods

• ductwork to distribute fresh air throughout the home and to return stale air to the HRV

• fans to circulate air throughout the home and to exhaust stale air to the outdoors

• a heat-exchange core, where heat is transferred from one air stream to the other

• filters to keep dirt out of the heat-exchange core

• a defrost mechanism (some units use a preheater) to prevent the heat-exchange core from freezing and blocking when the temperature of the incoming air is cold.

• a drain to remove any condensation from inside the unit (HRV only – ERV does not have it)

• operating controls to regulate the unit according to ventilation needs

Your ERV / HRV unit requires periodic checking and maintenance.

The Seven Steps to Healthy House with a proper HRV / ERV maintenance

Step 1: Turn Off Your unit: First, turn off your unit and unplug it.

Step 2: Clean or Replace Air Filters: Dirty or clogged filters can lower ventilation efficiency. Try to clean your filters at least every two months. Filters in most new units can be easily removed, cleaned with a vacuum cleaner, then washed with mild soap and water before being replaced. Older units have replaceable filters. If your unit is easily accessible, this is a five-minute job.
Step 3: Check Outdoor Intake and Exhaust Hoods: Remove leaves, waste paper or other obstructions that may be blocking the outside vents of your unit. Without this vital airflow, your unit won’t function properly. During winter, clear any snow or frost buildup blocking outside vents.
Step 4: Inspect the Condensate Drain: Check to see if your HRV has a condensate drain — a pipe or plastic tube coming out of the bottom. If it does, slowly pour about two liters of warm, clean water in each drain pan inside the HRV to make sure it is flowing freely. If there’s a backup, clean the drain.
Step 5: Clean the Heat Exchange Core: Check your HRV/ERV owner’s manual for instructions on cleaning the heat exchange core. Vacuuming the core and washing it with soap and water will reduce dust that can build up inside the core.
Step 6: Clean Grilles and Inspect the Ductwork: Once a year, check the ductwork leading to and from your unit. Remove and inspect the grilles covering the duct ends, then vacuum inside the ducts. If a more thorough cleaning is required, call your service technician.
Step 7: Service the Fans: Remove the dirt that has been accumulated on the blades by gently brushing them. Most new units are designed to run continuously without lubrication, but older models require a few drops of proper motor lubricating oil in a designated oil intake. Check your manual for complete instructions.

Your HRV should be serviced annually. If you are not comfortable doing it yourself, contact a qualified technician.