Replacing MVHR filters: which filter set fits your ventilation unit

Short answer: replace the filters of your MVHR (heat recovery ventilation) unit twice a year, or every six months when the filter light comes on. Which filter set you need depends not just on the make but on the exact model and sometimes the year of manufacture. Check the rating plate on the side or underside of the unit, look up that model below and order the matching set. A filter change takes five minutes and you do not need any tools.

Waarom filters vervangen belangrijker is dan mensen denken

A balanced ventilation (MVHR) unit continuously draws outside air in and extracts stale indoor air. The filters catch dust, insects and pollen. When they clog up, three things happen at once: the fans have to work harder (more electricity and more noise), the volume of supply air drops so moisture lingers in the house, and the dust that does get through settles on the heat exchanger. That last component is the most expensive part of the unit. So filters costing twenty euros prevent a repair costing a few hundred euros.

In practice, engineers find that filters are on average left in far too long. A grey filter you can no longer see through stopped doing its job months ago.

How often should you replace them?

The rule of thumb is twice a year: in spring after the pollen season and in autumn before the heating season. If you live on a busy road, have pets or are renovating, three times a year is more realistic. Most modern units have a filter warning that comes on after a set number of operating hours; you reset that warning after the change via the control panel.

Beating out or washing filters is pointless. The filter medium is a fleece that loses its filtering effect after cleaning and also deforms when washed wet.

Which filter class do you need?

The packaging states a class. Roughly speaking:

• G3 / G4 (now ISO Coarse) — the standard dust and insect filters that virtually every unit uses as standard.
• F7 (now ISO ePM1) — pollen filter, finer material, stops pollen and fine dust. Only fit it in the supply side, and only if your unit is suitable for it: a filter that is too fine in a unit not designed for it reduces the airflow.

Not sure? Then choose the class the manufacturer specifies for your model. You will find it in the manual and in the description of the filter set in our catalogue.

Filter sets by make and model

Below are the most requested sets. If your model is not listed, search for the model on the rating plate in the spare parts catalogue; it lists the filters of all the brands we supply.

Itho Daalderop

Check the year of manufacture: Itho Daalderop changed the filter size in 2009. A set for a unit from before 2009 will not fit a newer appliance, even if the model has the same name.

Brink

Zehnder and Stork

The WHR series was originally launched as Stork and later continued by Zehnder; both names refer to the same unit. The week cut-off in 2001 determines which size you need. If there is no production week on the rating plate, measure the old filter.

Ferroli

Replacing filters in five steps

Switch the unit off or to the lowest setting before opening the cover; that way you do not suck loose dust into the ducts. Then open the filter covers, usually with a click or twist fastening, and pull the old filters straight out. Note how they were fitted: many filters have an arrow for the airflow direction. Vacuum the filter compartment, slide the new filters back in the same position and close the cover. Finally, reset the filter warning on the control panel; otherwise the light stays on and the counter for the next change will be wrong.

Write the date on the edge of the filter with a marker. Then next time you will not have to guess when they went in.

When should you call in an engineer?

Changing filters is very much a job you can do yourself. You need an engineer if the warning keeps coming back with fresh filters, if the unit has become much louder or keeps squeaking, if water is coming out of the unit, or if the heat exchanger itself is dirty. That last one requires dismantling and cleaning, and sometimes replacement. Balancing the airflow per room is also a job for an engineer: it is done with a measuring instrument, not by feel.

Background on healthy ventilation and damp problems can be found under Milieu Centraal.

Frequently asked questions

Hoe weet ik welk type wtw-unit ik heb?

There is a rating plate on the unit, usually on the side or underside, showing the make, model and often the year or week of manufacture. Take a photo of that plate; with the make, model and year of manufacture you can find the matching filter set in our catalogue. If in doubt, you can also email us the photo.

Can I wash or beat out MVHR filters?

No. That damages the filter medium and it will no longer filter as intended. Beating it out also only removes the coarse dust; the fine particles that cause the resistance stay put.

What happens if I do not replace the filters?

The unit delivers less air, so moisture and stale air linger in the house. The fans run harder, which costs more electricity and makes more noise. In the long run the heat exchanger gets dirty, and that is a considerably more expensive repair than a set of filters.

Are more expensive pollen filters always better?

No. An F7 or ePM1 filter stops more fine dust and pollen, but also creates more resistance. Only units designed for it can compensate for that. Only fit a pollen filter on the supply side, and only if the manufacturer specifies it for your model.

Do filters from another brand also fit?

Only if the size and class match exactly. We supply both original manufacturer filters and universal sets from Comfort Line; both state which units and which years of manufacture they fit. We take that information from the manufacturer's documentation and do not add anything of our own.