Flexit SL4R Filters

Flexit is one of the most popular MVHR manufacturers in Norway and the other Nordic countries, and our range includes filters for the most commonly used residential models – Nordic S2/S3, S4R/S6R/S7R, S3R/K3R, and the UNI series. The model name is usually printed on the front panel label, right above the filter access opening. If you can't read the name, the filter dimensions (length, width, thickness in millimetres) are the most reliable way to find the right product in our catalogue.

Flexit's S-series units (Nordic S2/S3, S4R/S6R/S7R) are designed for a cold climate and typically come with an M5-class filter for extract air and an F7 (ePM1)-class filter for supply air. In some models, a second F7 filter is used instead of the M5, giving an F7+F7 set – the exact combination depends on the specific model, so it's best to check your unit's user manual or compare it with the set we list for each model.

Flexit heat exchangers are optimised to work in sub-zero temperatures, so during the cold season the unit often runs at a higher and steadier airflow to maintain heat recovery efficiency. Because of this more intensive operation, filters can fill up somewhat faster than in the warmer months, so it's worth doing an extra check in the middle of winter rather than waiting for your usual schedule. In Norwegian this is called “filterbytte” – filter changing – and the term is often mentioned in Flexit user manuals as well.

The filter compartment on Flexit MVHR units is reached by opening the front cover without any tools – usually just loosening the latches or screws by hand is enough. After removing the old filter, check the airflow direction arrow on the new filter's frame and insert it in the same orientation. If you're unsure of the exact steps for a specific model (e.g. SL4R), the manufacturer's user manual provides a detailed, photo-illustrated procedure – it's the same across the whole S/SL series.

Yes, we accept wholesale orders:

• for apartment building homeowners' associations
• for managers overseeing several buildings
• for landlords with multiple Flexit units

A larger discount per unit applies above a certain quantity. Send us the models of your units and the quantity needed – we'll prepare a consolidated order and arrange a convenient delivery schedule, so there's always enough filters for every MVHR unit in the building.