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.

In use, yes, provided two things match. Zehnder's original filters are made by the manufacturer; our compatible filters are produced at EU manufacturers' facilities to the same ISO 16890 classes and cut to the exact ComfoAir housing dimensions. Because ComfoAir filter housings are made to tight tolerances, a correctly sized compatible filter seats without air slipping past the edges, and at the same class it captures the same particles. The two things that must match are the class — for Zehnder, F7 on supply and G4 on extract, which is what Austrian practice expects — and the dimensions of your exact ComfoAir or Q model. The difference is price, and it is usually noticeable.

On the ComfoAir Q range the reset is done from the control panel or the ComfoControl app, in the menu where the filter status is displayed; on older ComfoAir models (160, 200, 350, 550) it is a button sequence on the unit's own control, described in the manual for your model. It matters more than it sounds, because the reminder is a runtime timer rather than a measurement — if you do not reset it, the next prompt arrives at the wrong point in the cycle and you either change too early or run past the interval. Do the reset immediately after refitting the front panel, while you are still standing at the unit.