Air Exchanger Usage

Source: Office of Energy Efficiency

Once the HRV was installed, balanced and put in working order, its current use is relatively simple. By following the general guidelines below and following the instructions of the manufacturer and the installer, you can help ensure the safe and reliable performance of your HRV.


Familiarize yourself first with the HRV's controls that let you adjust the air exchange rate and, to some extent, the humidity in your home. Depending on the type of installation and the HRV model, orders can be found on the device itself or in the kitchen, laundry room, bathroom or hallway. Pollutant sensors can be installed in other rooms of the house. In general, the main control device HRV is placed next to the main house thermostat.

  • Again, depending on the installation and the HRV model type, the controls may include the following functions:
  • controls high speed and low speed;
  • control for adjusting the recirculation mode to circulate the air inside the house without the exchange of indoor and outdoor air;
  • humidistat, which triggers high-speed HRV mode when the humidity levels in the home reaches a predetermined level;
  • timer, which put the HRV at high speed at given intervals;
  • setting of intermittent exchange mode, which automatically turns on the HRV at low speed at specified intervals;
  • pollutant sensors, used to increase the ventilation rate when the pollution level of the house rises;
  • maintenance indicator, which turns on automatically when the filters or other items should be cleaned or changed.

Low-speed operation

To ensure the removal of indoor pollutants and an external supply of fresh air, HRV should be operated at low speed continuously throughout the year, especially in tight homes and homes that have average levels of pollutants.

In most cases, a low-speed operation will meet your needs for air renewal (for exceptions, see below section on "High-Speed") and will be more effective than intermittent high speed. Intermittent exchange mode is suitable when pollutant levels are low, the house is not very tight, or the occupants are away for extended periods.

If you turn off the HRV, consider other arrangements for ventilation by opening windows for example.

High-speed operation

Under certain conditions, it may be necessary to increase the rate of renewal of the air in your home through high-speed mode. Depending on the type of installation, high speed cycle can be triggered manually or by timer, humidistat or other commands.

A high-speed operation is often needed in the kitchen and bathrooms. We may use:

  • when using paints, solvents, cleaning products and other household chemicals;
  • when the house air seems stale, this smells or is too wet;
  • when there are many people in the house, during a party, for example.

The operation of the high speed ventilation also helps improve the air quality when people smoke in the house. Tobacco smoke is one of the pollutants most noticeable and harmful indoor air. Wherever possible, it should restrict smoking in rooms where the air is exhausted directly outside or through the HRV or through a separate exhaust system (such as a kitchen).

Smooth operation at high speed, or permanent, may be desirable during the first year following the construction of the house in order to remove moisture and pollutants generated by new construction materials.

HRV are not air purifiers and may not be effective in the presence of extraordinary sources of indoor air pollutants (eg., Adhesives strong odors), especially if the pollutants are of a piece that is not directly connected to the HRV. In such cases, it is necessary to encourage occupants to reduce activities that generate pollutants or install a dedicated exhaust.

During the heating

Most have a HRV Automatic Defrosting is activated when the temperature of the outside air is below -5 º C. A defrost mechanism is needed where the climate is cold because the temperature of the moist exhaust air from the house is lowered (to warm the incoming fresh air) as to produce condensation and frost on the walls the core of the heat exchanger. The accumulation of ice can obstruct the flow of air through the HRV.

One strategy is to use the defrost registers to temporarily block the fresh air and allow the warm air from the house, through the HRV, melt the accumulated frost. The HRV returns to normal operation after the automatic defrost cycle. As the air cools in the winter, the cycle begins to increase.

Another method is to use an electric resistance heater to preheat the fresh air before it enters the nucleus. With this strategy, the defrosting is not necessary because the preheating prevents frost from forming.

To minimize condensation on cold surfaces such as windows during the heating season, set the humidistat to your HRV accordingly. Remember, it is not necessary that the air in the house becomes too dry, as this can cause static electricity and throat irritation. If the air in your home is too dry during the heating and you have attributed to the HRV, refer to "Troubleshooting the HRV."

Outside the heating period

The best strategy is to run your HRV continuously throughout the year, even during the non-heating. Except for a higher setting of the humidistat, the operation should be essentially the same as during the heating period.

You may be the HRV keeps the home cooler and quieter than if you had opened the windows to ensure the renewal of the air you will see. Keeping the windows closed also enhances security and reduces the amount of pollen and dust in the house.

Some modern HRV allow you to disable the low-speed setting. Even if this setting is disabled, you can still run the HRV at high speed in order to remove excess moisture and odors from the kitchen and bathrooms. This option is useful in the summer when the windows are open throughout the house, does not necessarily justify the operation of the mechanical ventilation.

By removing some of the heat from the incoming air, most HRV reduce the load on the air conditioner, which enables you to save money.

In all seasons

If your HRV is operating, keep contaminants away from the fresh air inlet. For example, do not place garbage near the HRV input, do not use pesticides or herbicides near your barbecue and against the wind. If you need to temporarily generate pollutants near the HRV entry, discontinue use until the end of the activity.