Published · Updated · By the MVHR Expert engineering team
Why people turn it off
- Concerns about running costs
- Noise
- Feeling cold air in winter
- Not understanding what it does
Why it's usually a mistake
Airtight homes have no accidental ventilation. When MVHR stops, moisture from breathing, cooking and showers stays in the home. Condensation on windows can start within days and mould within weeks.
The fans are low-energy and designed for continuous use. The savings from turning it off are small compared with the cost of damp and mould.
If it's too noisy or too cold
Those are service issues, not reasons to switch off. Noise is usually fans, filters or valve settings. Cold supply air in winter can mean a stuck bypass or an imbalance. Both can be fixed.
When switching off is acceptable
Short periods when the unit is being serviced or repaired, or when the manufacturer's instructions specify it, are fine.