HRVs and ERVs do require energy to run, but this energy is offset by the heat recovered from the exhaust air. Airtight homes equipped with heat recovery systems will have substantially lower energy costs per year than having ventilation without heat recovery. However if the house was significantly under-ventilated prior to the installation of the HRV/ERV the overall energy cost might go up due to the increased but now adequate ventilation rate.
To ensure that you home is well-ventilated and maintains good air quality, your HRV and ERV should run continuously. Many HRV fans can operate at low, medium, or high speeds depending on the ventilation requirements. A common control strategy is to have the HRV run continuously at low or medium speed, and switch to high speed when a higher ventilation rate is needed, such as when the bathroom is in use or during high occupancy periods.
For more information about HRVs, visit the Heat Recovery Ventilation Guide for Houses.
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