duct sizing

howseAugust 6, 2012

I have a 3300SF house with 900 SF upstairs and the remaining footage downstairs. The house is heated/cooled by a one zone system, utilizing a 4 ton cooling unit and a 115000 BTU gas furnice, split system. I want to add a heatpump upstairs utilizing its own duct work indepenant of the main system. My question is if I size and replace the dowwnstairs system to the remaining 2500SF, will I be able to utilize the downstairs existing duct work if I block off the upstair runs? Thanks.

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I see no reason why you could not use the existing duct work for first floor. It might be a little bigger than needed on some runs but it should cause no harm.

    Bookmark   August 6, 2012 at 4:29PM
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Thats my thought. The duct size maybe a little large for say a 3 ton heatpump, but a good variable speed fan might make up the differance.

    Bookmark   August 6, 2012 at 10:09PM
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