Zehnder WHR

Zehnder ComfoAir units use two filter classes:

• G4 (ISO Coarse) — protects the heat exchanger; used on the extract side
• F7 (ePM1) — for the supply air, capturing fine dust and pollen

For most ComfoAir models we stock both a G4+F7 set and a G4+G4 set. The G4+F7 set is the better choice for allergy sufferers and homes near busy roads.

Find the exact model on the unit's front panel — for example ComfoAir Q350, Q450 or Q600, ComfoAir 350/500/550, ComfoD 350/450/550 or Zehnder EVO. That is the fastest way to match the correct filter set in our catalogue. If the label is missing, measuring the extract and supply filters directly identifies the right size just as reliably.

Because ComfoAir's F7-class supply filter is specifically designed to capture fine airborne particles including pollen, it can load up faster during spring and early summer than during the rest of the year. Checking filters monthly during peak pollen season, even within the standard 3–6 month replacement window, helps maintain steady airflow and allergy protection.

Yes. The ComfoAir Q350, Q450 and Q600 — and the ComfoAir E350 — all take the same filter set, available as G4+F7, G4+G4 or an activated carbon version. Older ComfoAir models (70, 160, 180, 200, standard 300/375 and 350/500/550) each take a different size, so check your model on the front panel before ordering.

No. The Belgian energy performance framework — PEB in Wallonia, EPB in Flanders — sets requirements for how the ventilation system is designed and what air flow rates it achieves, not for which brand of consumable you buy years later. What does matter is that the replacement filter has the same class and the same dimensions as the one the system was commissioned with, so the pressure drop and therefore the flow rates stay as designed. A compatible F7/ePM1 filter cut to your ComfoAir's dimensions does exactly that. What would cause a problem is fitting a coarser class than designed, or a much denser one that pushes the fans outside their working range.

On the ComfoAir Q range the reset is in the control panel or the ComfoControl app, in the menu showing filter status; on the older ComfoAir models (160, 200, 350, 550) it is a button sequence on the unit's own control, set out in the manual for your model. It is worth doing straight away, because the reminder is a runtime timer rather than a measurement of how loaded the filter is — if it is not reset, the next prompt arrives at the wrong point in the cycle and you end up either changing too early or running well past the interval. Do it while you are still standing at the unit, right after refitting the panel.