Air Exchangers Ottawa

Are You Looking For An HRV or ERV?

Air Exchangers Ottawa

What Does Air Exchanger Do?

A good air exchanger will diminish a lot of the polluted air in your sealed home specially during winter times in Ottawa. Another good thing is that the heat energy is recovered while the air exchanger is ventilating your home. Proper ventilation is now part of the building codes and renews the air of the house at a controlled rate.

How to Determine the Size of Air Exchanger?

How much fresh air is required and the best way to provide it, determines the size of the HRV or ERV units. Energy recovery from exhaust air is becoming common place in cold regions, specially in Ottawa The two types of equipment can do this is an HRV (Heat Recovery Ventilation) and an ERV (Energy Recovery Ventilation).

Choosing between an HRV and an ERV

Heat Recovery Ventilation (HRV) is a system that uses the heat in stale exhaust air to preheat incoming fresh air. This reduces the energy required to bring outside air up to ambient room temperature. The ‘efficiency rate’ of an HRV unit determines how much energy will be saved by using that particular device. Although it requires the operation of a fan on a continual basis, the energy recovered from the inside air is many times that of the energy required for the fan.

Energy (or Enthalpy) Recovery Ventilation (ERV) goes a little further than the HRV scheme, as this type of system also captures some of the humidity in the air to keep it on the same side of the thermal envelope that it came from. So in winter, the system transfers the humidity from the air being extracted to the incoming fresh (and dry) air to help keep the ambient humidity level at a reasonable value (between 40 and 60%) at all times. In summer, the humidity transfer reverses and the humidity in outside air is removed before it is injected into the home. This saves energy by reducing the load on your air conditioning system and/or dehumidifier. A high efficiency of humidity transfer would be around 70% but this value depends on the actual humidity on either side of the envelope.


The best option between an HRV and an ERV depends on your climate and specific needs. If your house is too humid in winter (above 60% RH) then an HRV is the better choice, as it would surely get rid of excess humidity while an ERV would tend to keep it at a high level. One thing is for certain though, whichever you choose, an airtight home with an ERV or HRV is an evolutionary leap beyond the leaky houses of the 20th century, so if  you are building or have a reasonably airtight house, don’t lose sleep over which one to get – just get one.

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