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Rules of filter selection for the air handling unit

Table of contents

Which filter to select from all the alternatives? Whether it is SALDA, Komfovent, Systemair, Flexit or Wolf AHU, the basic rules are as follows:

1. Technical documentation of the manufacturer

The AHU comes with the original set of filters. The ventilation units are tested according to these filters. The manufacturer specifies filter alternatives to this ventilation unit. Therefore, if you choose another class of filters (e.g. cheap Coarse instead of ePM10 or more effective ePM1, if only Coarse is allowed), you would violate the warranty requirements and in case of unit failure, manufacturer may not apply the warranty.

2. Outdoor air pollution

A. You live near an industrial district, busy streets and in a big city territory, the particulates greatly exceed World Health Organization norms. For air to meet the requirements, an ePM1 (F7) class filter is required, as not only pollen is harmful to health.

B. If you live in a suburban area or in a small settlement, the air pollution is not that high, the ePM10 (M5) class filter is enough. Although there is an exception, if the pesticides, herbicides or fungicides are sprayed by the farmers near your home, choose ePM1 class filter, at least in a high season

C. If you live in nature, the same air quality as the outdoors is right for you, and Coarse (G3-G4) class filters are enough.

Which quality of air do you have? Pollution data is here: 

3. Your sensitivity to contaminants

If you suffer from allergies or asthma, do not spare money for the ePM1 (F7) class filter. Do you feel blissful in a supermarket when you suffer from hay fever? They use ePM1 class filters there as a standard.

4.Only tested filters

As the new classification ISO 16890 is already in force since 2018 July, self-respecting manufacturers have tested their filters and provide their classification according to a new standard. Most often near the old class G3, G4, M5, M6, F7, etc. they also indicate their new class Coarse, ePM10, ePM2.5, ePM1, and its efficiency in percent. So called “household producers” do not do this, probably due to testing costs and low quality, so basically you get a cat in the bag. There is no purpose then to pay for their F7 filter for bigger money if, for example, fine particles can come though filter connections.

5. Never use the ePM1 (F7) filter to clean the air from the home

The ePM1 or ePM2.5 (F8, F7) filter has higher pressure losses than the ePM10 (M5, M6) or Coarse (G3, G4) class filters, so the extract air fan uses more energy for the same flow. What does it mean? It’s money down the drain. Why is this done? Smaller warehouse … This applies not only to merchants but also for example. manufacturers of AHU such as FLEXIT, Komfovent. In other words WTF … Optimal options: ePM1 + ePM10 (F7 + M5), ePM1 + Coarse (F7 + G4 / G3), ePM2.5 + ePM10 (F7 + M5), ePM2.5 + Coarse (F7 + G4 / G3), ePM10 + ePM10 (M5 + M5), ePM10 + Coarse (M5 + G4 / G3).