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Community and Q&A

ERV, HRV or whole house dehumidifier

Nick Chamberlin/Marine4C | Posted in General Questions on

We are in the process of building a new home. The location is outside Seattle, WA, Marine 4C, where the average humidity is 76 %. In a well-insulated home (2×8 advanced frame with blown cellulose and Zip-R sheathing R-6 exterior ) with <1.5ach50 would it make sense to install an ERV, HRV or whole house dehumidifier? Conditioned space is @3,200 sqft with a full basement w/ R-10 sub slab insulation and walls constructed with ICF’s, @ R-22. Heating is radiant flooring.

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  1. User avatar GBA Editor
    Brian Pontolilo | | #1

    Hey Nick.

    The short answer is yes, best practice is to install a balanced ventilation system in a home that tight, either an HRV, an ERV, or perhaps a ventilating dehumidifier. I'm not familiar enough with your climate to recommend a specific product. Perhaps some other GBA members will have opinions on that. When it comes to ventilation, though, this article is a good place to start: Balanced Ventilation Systems

    1. Nick Chamberlin/Marine4C | | #2

      Thanks for responding. We were planning on an ERV originally, but have never built a house this tight, per the current county regulations. I was curious if the ERV coupled with a whole house dehumidifier in the basement would just be over kill? I would rather have it in place than try to retro later.

      1. User avatar GBA Editor
        Brian Pontolilo | | #3

        Hi Nick.

        If you build a tight house and the HVAC system (assuming you will have AC, but not sure) is properly designed, you shouldn't need whole house humidification (again, I'm not so familiar with your climate).

  2. User avatar
    Jon R | | #4

    You will have weather with mild temperatures and near 100% humidity. If you want to be comfortable during these periods, you need dehumidification. But probably not an expensive whole-house unit.

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