When and How Often Should You Replace Ventilation Unit Filters?
How often should you replace ventilation unit (MVHR/AHU) filters?
Ventilation unit filters should be replaced once they reach the maximum dust load allowed by the manufacturer. Some systems include pressure sensors or relays that indicate when a filter is overloaded. In residential ventilation units, however, a simpler solution is usually applied — a timer, which has been mandatory since 2018 under EU Regulation 1253/2014.
The timer is typically set for 4 months. When this period is reached, the controller or mobile app will display a reminder that it’s time to change the filters.
When should you replace the filters sooner?
Filter wear depends heavily on the environment:
- ✅ If you live in a clean area, filters can last longer.
- ❌ If there is nearby construction or the air intake is close to a busy street, filters will need to be replaced sooner.
Filter lifetime also depends on the filter class you use: F7, G4, or F9.
Manufacturer recommendations
Manufacturer recommendations for filter replacement:
- ✅ Under normal conditions, it’s best to replace filters every 6 months – before and after the heating season.
- ❌ In polluted environments, replacement is recommended every 4 months.
If your ventilation unit has a timer, follow the reminders shown on the controller or mobile app.
Special cases
Wire frame filters or filter media pads: these can be vacuumed every 2–3 months, but after 3 cleanings they should still be replaced.
Brink Flair 450/600 G4+G4 Filter set (Standard)
Ex VAT: £5.29
| Manufacturer of MVHR | Brink |
| Manufacturer | CleanFilter |
| Air handling unit |
|
| Filter dimensions | 595x200 |
| Class EN779 | G4+G4 |
| Class ISO16890 | Coarse 65% |
| Protection level | Basic: larger solid particles, dust, fluff. |
| Quantity of filters | 2 |
| Advantages |
|
| Manufacturer product number | 1669551 |
| Remarks | The filter set is designed to protect the MVHR from bigger particles. If you want to clean the supply air from small particles such as pollen and smog, choose the F7 class supply air filter. It is available in our shop. |
Activated carbon filters: their service life is shorter — around 3–4 months.
Domekt R 300 V 1xF7/AC Activated carbon filter (Odor)
Ex VAT: £14.58
| Manufacturer of MVHR | Komfovent |
| Manufacturer | CleanFilter |
| Air handling unit | Domekt R 300 V |
| Filter dimensions | 290x205x46 |
| Class EN779 | F7/AC |
| Class ISO16890 | ePM1 70% |
| Protection level | Particles and odors: fine particles, dust, pollen, mold spores, combustion particles, volatile particles, NOx, O3 gases. |
| Quantity of filters | 1 |
| Advantages |
|
| Remarks | 🌟 High-quality replacement filter: made from certified materials (Germany, SANDLER AG) with tested performance. Provides reliable air filtration and optimal service life. |
High-efficiency F9 filters: due to higher airflow resistance, they are also recommended to be replaced every 3–4 months.
SIBER DF EVO / EVO2 1xF9 Filter (smog&pollen)
Ex VAT: £9.82
| Manufacturer of MVHR | Siber |
| Manufacturer | CleanFilter |
| Air handling unit |
|
| Filter dimensions | 139x175x48 |
| Class EN779 | F9 |
| Class ISO16890 | ePM1 85% |
| Protection level | High: fine particles, dust, pollen, mold spores, combustion particles, smog particles, insecticide dust. |
| Quantity of filters | 1 |
| Advantages |
|
| Manufacturer product number | DFFF9 |
Undersized ventilation unit (too low capacity): filters will need to be replaced more frequently, approximately every 3–4 months.
How can you tell when your ventilation unit filters are clogged?
Main warning signs:
- 🔊 Increased ventilation unit noise.
- 💨 Reduced airflow indoors.
- ⚠️ Error messages on the controller (fan overload, excessive pressure drop).
How to replace ventilation unit filters?
You can find the full step-by-step guide here:
✅ Why is it important to replace filters on time?
- ✅ Better indoor air quality
- ✅ Quieter operation of the ventilation unit
- ✅ Lower electricity consumption
- ✅ Longer lifespan of the unit
Certified ventilation unit filters are delivered within a week across the UK.
❓ Quick answers to the most common questions
📅 How often should ventilation unit filters be replaced?
Normally — every 6 months; in polluted environments — every 4 months; according to the timer — usually around 4 months.
🔄 When should an F7 ventilation filter be replaced?
Depending on conditions — every 4–6 months or as indicated by the timer reminder.
💧 Can ventilation filters be washed?
Wire frame filters / filter media can be vacuumed; most other filters should not be washed — replace them with new ones.
⚙️ What is the difference between G4, F7, and F9 filters?
G4 — for larger particles, F7 — balance between resistance and efficiency, F9 — high efficiency but shorter replacement interval (3–4 months).