Mechanical Ventilation Heat Recovery (MVHR) systems draw in fresh air from outside, while at the same time extracting stale air from within the house. As the fresh air and stale air travel through the counter-flow heat exchanger inside the unit, the thermal energy from the used air is recycled and used to heat the fresh incoming air. An MVHR system can recycle up to 80%.
With virtually no moving parts, these units are low maintenance and simply require both filters to be changed at least once a year. Changing the filters is as simple as changing a light bulb.