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Community and Q&A

Multiple Zehnder ComfoAir 70 ERV good solution for Ventilation?

Bdegman | Posted in General Questions on
We renovated a 860 sq ft home to 1487 sq ft. It is sealed well, new windows, and fully insulated in climate zone 2A (Texas). We have all our duct work and air handler in the unconditioned attic along with our gas furnace and gas hot water heater (not a great idea now that we know more).

Problem now is we need a dehumidifier and would like to increase the quality of our air. CO2 and VOC gets very high at night. Any airing out we do with exhaust fans and opening windows fixes the problem, but humidity increases, the air is not filtered, and it’s not a sustainable solution. I’m hesitant to want to put a whole house ERV system in because of the duct work needed which might not even be possible with our current system and the maintenance needed in the attic (the attic hatch is in my sons room and makes a mess every time we have to go up there).

I was wondering if we could put a Zehnder ComfoAir 70 ERV (ductless system) in the 2 bedrooms and 1 in the living room of our 1487 sq ft house plus a dehumidifier to solve our problems? If so, would should I do a whole house dehumidifier in our hot attic or one in the house? Also, are there any other ductless ERVs that are better for our situation and size. Thank you!

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  1. Expert Member
    Michael Maines | | #1

    That would probably work, except the last I had heard, Zehnder was no longer providing the ComfoAir 70 to the US market. Something may have changed since I heard that.

    1. Bdegman | | #2

      Oh, I didn't realize that. Do you like Lunos? Or any other ones you recommend? Thank you!

      1. Expert Member
        Michael Maines | | #3

        I have used Lunos on several projects and think they are a good solution, just not ideal due to sound issues--they introduce a hole in the building envelope, and they change direction every 70 seconds which doesn't bother everyone but I notice it. And they're on the expensive side. But a good solution when more typical solutions won't work and you need ventilation.

        1. Bdegman | | #4

          thank you!

          1. Deleted | | #5


        2. Bdegman | | #6

          I have one more question for you. Could we install a whole house ERV on the side of our house and build a closet around it with insulated ductwork on the outside of our house? We have one side of our house that both bedrooms and bathrooms are on so it could work to possibly pull from the bathrooms and add to the bedrooms if ductwork could be along that wall on the outside.

          1. Expert Member
            Michael Maines | | #7

            I see no problem with building an insulated "closet" bump-out for the ERV, but ductwork should be inside the building envelope if possible, or at least protected from the weather in an attic space.

  2. Bdegman | | #8

    Thanks a lot for your help!

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