Flexit Uni 3 filters

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.

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.

It affects the extract filter, which is the one people forget. Air drawn from a sauna, washroom and utility room carries humidity, lint and fine textile fibres, and that mixture loads an extract filter faster and packs it more densely than ordinary room air. Two practical points follow. Check the extract filter as often as the supply one rather than assuming the supply side is the dirty one, and never fit the fine supply filter on the extract side to "do better" — swapping the two around is one of the most common mistakes, and it puts the wrong pressure drop in both places. Each side has its own class for a reason.

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.

Yes, we handle bulk orders for:

• Housing companies and their building managers
• Property managers looking after several buildings
• Landlords with multiple Flexit installations

Above four filter sets it is worth contacting us about the pricing rather than ordering at list price, and a valid EU VAT number gives 0% VAT at checkout with VAT invoices e-mailed automatically. Send us the unit models and quantities and we can put together a consolidated order and a delivery schedule that fits your maintenance rounds — collect the model per apartment, since buildings are often fitted out in phases.

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.