Description
If you are using a Frost protection pre-heater (a black box on the intake duct), which filters the air before it comes into the PAUL Focus MVHR system, then there is no need to have an additional filter in the MVHR system intake. However, you do need to put something in the slot for the MVHR intake filter to fill the gap and prevent air leakage. You can save money by using a Blank filter frame in the intake slot and install an F7 grade filter in the Frost protection pre-heater box and a G4 filter in the MVHR system extract. This will mean that in the future, you will only need to buy 2 filters instead of 3 as the blank filter frame doesn’t need changing.
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