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HRV Design

kennebecwoodworks | Posted in Mechanicals on

Hi I had a question about my HRV, I installed exhaust ports in the bathrooms and fresh air to the living, bedroom areas. I have a cupola on the center of the house which is about 5′ by 5′. The cupola shaft runs down through the house and I’m wondering if I should install an hrv port as high as I can to regain some of the heat that will be traveling up there? Around the cupola is insulated with 2′ hdsf and dense pack cellulose.

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  1. GBA Editor
    Martin Holladay | | #1

    You raise an interesting question. I don't think it's worth running a duct to your cupola.

    First of all, HRVs use a fairly significant amount of electricity to run, and every duct run that you add will cause the HRV fans to work a little harder (and therefore use more electricity).

    Second, if your house is fairly airtight, you are less likely to have much temperature stratification.

    Third, if the air in your cupola really is a few degrees warmer than the air on your floor, you can at least be grateful that the air in question is within your home's conditioned envelope.

    It's not clear whether reducing the temperature of that air (if indeed your plan succeeds in doing that) will actually improve the thermal performance of your house. While you may raise the temperature of the fresh air delivered by the HRV slightly, you will also be (probably) increasing your electric bill and changing the temperature profile of the air in your house in ways that are hard to model. Net benefit? I doubt it.

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