Published · Updated · By the MVHR Expert engineering team
MVHR in one paragraph
MVHR is a ventilation system for airtight homes. Two fans move air continuously: one extracts stale air from wet rooms (kitchen, bathrooms, utility) and one supplies fresh air to habitable rooms (bedrooms, living rooms). The two airstreams pass through a heat exchanger without mixing, so the warmth in the outgoing air heats the incoming air.
Why modern homes need it
Modern homes are built to be airtight to save energy. That means there are no accidental draughts to replace stale air, so moisture, cooking fumes, CO₂ and pollutants build up unless the home is ventilated deliberately. MVHR provides controlled, continuous ventilation without throwing away heat.
The main parts of an MVHR system
- The unit (fans, heat exchanger, filters and controls), usually in a loft, cupboard or ceiling void
- Supply and extract ductwork running to each room
- Valves or grilles in ceilings or walls
- Intake and exhaust terminals to the outside
- A condensate drain, because the heat exchanger produces water as warm humid air cools
- A controller or boost switch, and sometimes humidity or CO₂ sensors
What maintenance does MVHR need?
Filters need to be checked every 3–6 months and replaced every 6–12 months. The whole system should be professionally serviced annually: heat exchanger and fans cleaned, condensate drain checked and airflow measured against the design rates.
Is MVHR worth it?
In an airtight home it is not optional — some form of mechanical ventilation is required. The question is which type. MVHR recovers heat that extract-only systems throw away, which is valuable in a UK winter, but it needs space for ducting and regular maintenance to deliver its benefits.