What do HRVs and ERVs do during the heating season?

The function of Heat Recovery Ventilators (HRVs) and Energy Recovery Ventilators (ERVs) during the heating season is centered around their ability to efficiently manage air exchange while minimizing energy loss. They are designed to improve indoor air quality by bringing in fresh outdoor air and exhausting stale indoor air, but they do this in a way that conserves energy.

The correct function highlights that HRVs and ERVs absorb heat from the exhaust air that is leaving the home and transfer that heat to the incoming fresh air. This process significantly reduces the energy required to heat the incoming air during cold weather, making homes more energy-efficient and comfortable. HRVs focus primarily on heat recovery, while ERVs also address moisture transfer, making them effective in different climate conditions.

The other options do not accurately reflect the primary functions of these systems. Cooling the incoming air would contradict their operation during the heating season. Ventilating solely based on humidity levels is not their main function, as they are designed to also consider temperature. Lastly, stating that they rely on external heating sources for operation overlooks their capability to reuse and transfer heat from the home's exhaust air.