The three most frequently asked questions about air exchangers
What is an air exchanger, and what is it supposed to do?
An air exchanger, also known as a heat recovery ventilator (HRV) or energy recovery ventilator (ERV) is typically designed and installed to exchange the full volume of air in a home about four times every 24 hours. Modern air exchangers are also designed and installed to provide accelerated exhaust of air from bathrooms, kitchens and laundry areas when needed, all the while balancing atmospheric pressure indoors, by drawing fresh air into the home.
Do I run my air exchanger in the summer, or just the winter?
Choose a suitable relative humidity setting in the winter months and select the standby (often labeled "off" or "summer") setting in the spring, summer, and fall. If you have fan timer controls in the bathrooms, use them all year-round to increase ventilation and remove that surge of moisture from a bath or shower. In addition to the bath exhaust feature, an air exchanger will provide fresh air inside a home with closed windows, whether you are heating or cooling.
Setting the humidistat control at a level lower than indoor humidity provides a drying effect during the winter, by accelerating the flow of fresh air into the house. This is especially useful if you are experiencing condensation on cold windows or elsewhere, however can be counter-productive in summer, when you are trying to cool the house during hot and humid weather.
How much does it cost to run an air exchanger?
Operating costs will vary based on the manufacturer, the nature of the house and the occupancy, and the local weather conditions - but are generally negligible. This minor cost is offset in newer homes by heating and cooling savings, as well as the elimination of bathroom fans. There is inherent value as well in the fact that indoor air quality is greatly improved, while also eliminating conditions often conducive to mold growth.
Gil Strachan is a professional home inspector, representing Electrospec Home Inspection Services in east-central Ontario since 1994.