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Room HRV

Terry Grube | Posted in Mechanicals on

Just completed exterior renovation on a 200+ colonial. Removed everything from outside air sealed, installed roxul, plywood, taped joints, typar, 1 inch foam board, 3/4″ strapping, vertical grain clapboards, etc… I have an ell that the radon level is now slightly elevated because it is so tight. It is basically 20 X 30 and attaches to the main house via a large opening. It has the kitchen and living room in it. It is a slab which I did not do so not sure how leaky it is. I want to install a single HRV and was looking at twinfresh comfo, Mica 60, Mica 150 style through wall units. Does any one have any experience or thoughts on these units. Ideally I thought it might be good to have a slight (very slight) positive pressure to keep radon at bay while adding fresh air. I have a feeling the traditional radon mitigation would not work because I am almost confident there is not 4- 6 inches of crushed stone underneath the slab. Any thoughts are appreciated.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Terry,
    Two points:

    1. Radon mitigation contractors are experienced at installing radon mitigation systems in older homes that lack a layer of crushed stone under the slab. For an explanation of the methods they use, and for more information on radon mitigation, see this article: All About Radon.

    2. If for some reason you don't want to consult a radon mitigation specialist -- always the best approach -- you can install an HRV if you want. A continuously operating HRV will, indeed, lower the indoor radon concentration. It's impossible to predict whether an HRV will lower the radon concentration enough to bring the levels below the action level of 4 picocuries per liter.

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