Residential air filters from Interfil

Superb quality and superior service from a Quality and Environmentally Certified filter manufacturer

When should I change filters?

To ensure clean and fresh indoor air, it is important to change filters in the ventilation unit before they become too dense and soiled.

The best time to switch filters is in the fall before winter sets in.

Be aware that a ventilation filter has a limited life span and will eventually accumulate biological material such as contaminants (bacteria), pollen spores that emit allergens, and hazardous heavy metals.

Healthcare professionals therefore recommend to switch filters twice a year in exposed areas. This also applies to particularly sensitive people, such as pollen allergists.

Either way: You should not use a ventilation filter for more than 12 months. This is recommended by both specialists and in several standards such as VDI 6022 and EN 13779.

Therefore, if you choose the right ventilation filter and change the filter at least once a year, you are guaranteed clean air that contributes to a better indoor climate, fewer respiratory complaints and less absence from work due to sickness.

Economically, it will also pay off, as a dense, soiled filter requires more energy to push the air through the filter. Frequent changing also provide lower maintenance costs for channels and other systems.

A good bonus is that in case of frequent filter changes and the choice of the best possible filter, you actually save money.

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We supply ventilation filters from the Norwegian company Interfil. These are of the highest quality in Europe.

Your manufacturer may claim that your warranty may expire when using non-original filters. We can tell you that there are no such thing as «original» filters.

What they can point out, however, is 1: the use of poor quality filters and 2: that you have not changed at least once a year.

With us you get proof of both! You also achieve a healthy indoor environment 🙂

Which filter should I choose?

A filter should stop most possible particles, but at the same time without the air resistance (pressure drop) becoming too large. The higher the pressure drop – the higher the energy cost.

The Labor Inspectorate requires filters for minimum filter class ePM1 50% (previously «F7»). However, it is important to keep in mind that in areas with significant pollution levels, a finer filter should often be used, and preferably solutions with several filter steps (eg carbon filter).

A bag filter with a certain frame size may have different numbers of bags, different bag lengths, and thus large variations in the actual filter area. It is therefore important that you check that the filter area of what you order is sufficient in relation to the amount of air you are going to filter.

In fact, a filter that is cheaper in purchasing can cost a lot more if it does not hold its promises.

Interfil has its own test lab that ensures that the filter fits your ventilation unit.

This is why you should buy filters with us:

You can rest assured that the ventilation filter provides the best indoor climate when choosing a Norwegian filter from Interfil at Skjåk:

Interfil logo

1. Quality certificate

Interfil has the industry’s strictest product certification, the P-mark *. Interfil is also Eurovent and ISO certified. This is more than enough to maintain the warranty on your ventilation system.

2. Energy-efficient filter with low pressure drop

Products in filter class ePM10 to ePM1 (formerly M5 – F9) are energy labeled according to Eurovent 4/21.

3. Environmentally friendly ventilation filter

Interfil is the only filter manufacturer in Norway that is certified «Environmental Lighthouse».

All energy used at the factory and headquarters in Skjåk comes from locally produced renewable hydropower.

By purchasing short-travelled, Norwegian-produced ventilation filters, you contribute positively to the environment.

How to change filters in your ventilation system

These are general tips on how to proceed when changing filters. Different ventilation units naturally have different ways of changing the filter. Follow the instructions that follow your aggregate.

Filters by themselves contain no harmful substances, but filters that have made their work can contain unpleasant and harmful substances. Therefore wear gloves and preferably a mask. Contact us for a complete service package with protective equipment.

  1. Wait to open the unit door until the fan has stopped completely
  2. Carefully remove used filters. Put them in plastic bags before they can be placed in the packaging
  3. Check that there is no dust on the clean air side behind the filter. Filter exchange is a good opportunity to take a simple cleaning of the unit.
  4. Check that gaskets and tension springs in any mounting frames are in order
  5. Take the new filter carefully out of the carton and make sure it is not damaged
  6. Make sure that you insert the correct filter in relation to what is described for the plant (correct number of filters and correct area)
  7. Remember standing bags in the filter if you use bag filters. The bags must NOT lie flat!
  8. Carefully insert the filter. Make sure that any bags do not get caught or damaged by any sharp objects in the ventilation system.
  9. Make sure that there is a tight seal between the filter and the unit door (seal!) so that leakage does not occur.
  10. Make sure that used filters are deposited correctly. Filters with flammable frame should be used as an energy source and delivered to combustion plants

* The P marking is a voluntary certification scheme that RISE Certification (formerly Swedish Technical Research Institute) manages and which is the best insurance you can get to ensure that the filters you buy actually keep that manufacturer promise. RISE poses requirements for both product and production, and certification goes way beyond ISO standard and is by far the strictest certification scheme available in the industry.

Unfortunately, many filter manufacturers promise more than they can, and it’s not uncommon to find product ads where the manufacturer provides technical data that they never manage to achieve in real life.

Read more about the P brand and filter quality in our blog!

We have several filters in stock and guarantee the lowest price on identical type of filters of the same quality.

See also our filters for business and industry.

Your home deserves the best!


We give you a health indoor climate

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