Mechanical ventilation and heat recovery (MVHR) systems exchange stale air for fresh air, and recover heat in the process. Every property needs fresh air to come in from outside so that the occupants can have good indoor air quality. It’s also vital that stale, damp air and pollutants are removed to protect the health of the people living in the dwelling, as well as the integrity of the building.
Today, any new home is generally constructed under the principles of ‘fabric first’, which ensures that the building’s envelope is thermally efficient, well-insulated and airtight to reduce heat loss. But as modern homes become evermore airtight, they also need to be well-ventilated, but cost-effectively and efficiently. Hence ventilation systems with energy-saving heat recovery are an increasing feature of new build homes.
MVHR systems are generally fitted in lofts, eaves, ceiling voids, kitchen/utility cupboards or garages, and comprise a heat exchanger and ducting system. Providing continuous air supply and extraction, they remove contaminated, wet air from frequently wet rooms such as kitchens, utility rooms, washrooms and bathrooms, and then recycle the heat into the fresh air supply going into the other living areas.
Some MVHR products include a summer bypass valve, which, when automatically activated, diverts incoming air away from the heat exchanger. This prevents warm air inside a dwelling being further heated on the hotter days of the year, which helps towards reducing the risk of overheating.