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Zehnder ComfoAir 350 dust in house

Matthew_Utah | Posted in General Questions on


I’ve been reading this site for years. However, this is my first post!

I have a passive house that’s located in Park City, UT. It gets dusty here in the summer; however, it’s winter now with 8+ feet of snow on the ground.

We have a Zehnder ComfoAir 350, and I check the filters every three months and change them every six months. We end up with dust/dirt around the interior supply air vents pretty quickly, along with dust all over the house.

Has anyone ever experienced this with an HRV?

This is the house:

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  1. ERIC WHETZEL | | #1

    How often do you clean the core? If it isn't being cleaned on a regular basis (around once a year), it's certainly possible that dust is bypassing the filters and the core and getting to your supply diffusers.

    We haven't had issues with dust, but in the spring we do get some gnats that manage to bypass the filters and the core (fortunately this only lasts for a week or two and there aren't that many).

    1. Matthew_Utah | | #3


      I've never cleaned the core. I will give that a go!

  2. Expert Member
    Akos | | #2

    Passive house in dry climate generally implies radiant heat.

    Common misconception is that radiant doesn't make any dust. True enough but the HVAC is rarely the source of dust in the house, we humans are. Without an air handler with a decent filter always cycling house air, the air in a radiant house will generally have more dust. In my home with radiant heat, the intake filters on the ERV get a pretty solid buildup after a couple of months even though the fresh air is filtered by a Merv13+HEPA filter.

    The dust you are seeing around your fresh air feeds is simply house air. The higher velocity air from the fresh air supply is at lower pressure so it tends to draw house air into the stream, this dust than settles out on the grill and around the drywall if the grill is not well sealed.

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