Flexit Nordic S2/S3 filters

Our house brand Flexit sets are F7+F7 — a fine F7 (ePM1) filter on both the supply and extract side — and the Econordic W4/WH4 and SL4R originals are F7+F7 as well. That protects the heat exchanger and gives strong filtration of fine dust and pollen in the incoming air.

We supply filter sets for Flexit's most widely used residential lines — Nordic S2/S3, S4 and CL2/CL3/CL4, UNI 2, UNI 3 and UNI 4, Econordic W4/WH4 and SL4R — common across Norway and the other Nordic countries. For Nordic and UNI units you can choose between Flexit originals and our house brand. The model designation is usually printed on the label on the front panel.

Yes, we handle bulk orders for:

• Apartment buildings and owners' associations
• Building managers looking after several properties
• Landlords with multiple Flexit installations

Volume pricing applies above four filter sets, and a valid EU VAT identification number gives 0% VAT at checkout with invoices e-mailed automatically. Send us your unit models and quantities and we can put together a consolidated order and a delivery schedule that fits your maintenance rounds.

Flexit's heat exchangers are optimised for sub-zero climates, and units often run at higher, more consistent airflow through cold months to maintain heat recovery efficiency. That steadier airflow can mean filters reach saturation a little sooner than in milder seasons, so a mid-winter check is worthwhile.

No, standard filters are fine. The F7 filter media in our Flexit sets handles the temperature and humidity swings of Nordic installations, so no special low-temperature filter is needed. What matters more is checking the filters a little earlier in winter, when higher sustained airflow can bring the change forward.

Usually it means the configured interval has elapsed, not that the unit has measured a loaded filter. In most residential ventilation units the warning is a runtime timer set at commissioning, so it runs on hours rather than on how dirty the filters really are. In a dusty location the filters can be visibly grey weeks before the warning appears; in a lightly used apartment they can still look serviceable when it does. Treat it as a prompt to open the unit and look. Austrian guidance is to check at least quarterly regardless of what the display says, and to replace one to three times a year. Reset the timer after changing so the next prompt is correctly timed.