MVHR systems provide continuous ventilation by extracting stale air and supplying fresh, filtered air into your home. The filters inside the unit capture dust, pollen and other airborne particles, keeping them out of your living spaces and protecting the internal components of the MVHR unit. Over time those filters clog with accumulated debris — and that is when the problems start.
What happens when MVHR filters are not changed
Reduced airflow
Clogged filters restrict the system's ability to circulate air effectively, resulting in diminished ventilation performance.
Increased energy consumption
The unit has to work harder to move air through dirty filters, leading to higher energy use and increased running costs.
Decreased indoor air quality
When filters are saturated they are less effective at trapping pollutants, allowing contaminants to circulate within your home.
Potential system damage
Accumulated debris causes unnecessary wear on the fans and heat exchanger, potentially shortening the lifespan of the MVHR system.
In short, clean filters are what keep an MVHR system doing its job: fresh filtered air, recovered heat, and a unit that lasts. MVHR filters are also designed to be replaced, not cleaned — vacuuming or washing damages the media and destroys its rated efficiency, so replacement is the only correct maintenance.
How often, which filter, and how to change them
We cover the practical side in dedicated guides, so this page can stay focused on the why:
- How often should you change your MVHR filters? — the timings, and how to tell when a filter is overdue.
- How to find the right replacement MVHR filter for your unit — identifying the correct part first time.
- MVHR filter grades explained — what G4, M5 and F7 mean, and the ISO 16890 equivalents.
Find genuine filters for your unit
We supply genuine replacement filters for the major UK brands, including Systemair, Villavent and Vent-Axia, at trade-friendly prices. Browse MVHR & ventilation replacement filters, or send us your unit model and we will confirm the right one.
Shop the range: explore our full selection of MVHR units and heat recovery systems. Whole-house and single-room options are in stock with next-day delivery.