How a Heat Recovery Ventilator Works
Heat recovery ventilation systems allow R-2000 homes to maintain high indoor air quality without excessive additional energy costs.
As shown in the diagram below, a heat recovery ventilator (HRV) consists of two separate air-handling systems – one collects and exhausts stale indoor air; the other draws in fresh outdoor air and distributes it throughout the home.
Components of a Heat Recovery Ventilator
Heat Recovery
At the core of an HRV is the heat transfer module. Both the exhaust and fresh-air streams pass through the module, and the heat from the exhaust air is used to pre-heat the fresh-air stream. Only the heat is transferred; the two air streams remain physically separate. Typically, an HRV is able to recover 70 to 80 percent of the heat from the exhaust air and transfer it to the incoming air. This dramatically reduces the energy needed to heat fresh air to a comfortable temperature.
Air Exchange
The HRV system installed in an R-2000 home can change all the air in the house over a three-hour period. Most HRVs are also equipped with automatic humidity sensors that increase the ventilation rate when needed – for instance, when you use the shower. Exhaust air is normally collected from the kitchen and bathroom areas, where most moisture and odours are created.
System Connection
To ensure that fresh air is supplied to all living areas in an R-2000 home:
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For homes that have forced-air heating – the HRV is usually connected to the heating system ductwork. This requires running the furnace fan continuously to distribute fresh air throughout the house, increasing operating costs. However, the improvement in air quality is significant.
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For homes that don’t have forced-air heating – the HRV is connected to a specially installed network of small-diameter fresh-air ducts.
R-2000 is an official mark of Natural Resources Canada.
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