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 outdoor air and distributes it throughout the home.
Components of a Heat Recovery Ventilator
At the core of an HRV is the heat transfer module. Both the exhaust and outdoor air streams pass through the module, and the heat from the exhaust air is used to pre-heat the outdoor 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 outdoor air to a comfortable temperature.
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.
To ensure that outdoor air is supplied to all living areas in an R-2000 home:
- 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 outdoor air throughout the house, increasing operating costs. However, the improvement in air quality is significant.
- For homes that don’t have forced-air heating – the HRV is connected to a specially installed network of small-diameter outdoor air ducts.
Read original article at the Office of Energy Efficiency (OEE)
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