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Heat load in a SIP house.

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mjstef
mjstef Member Posts: 1
OK seasoned installers, give me some feedback on this. Building a house for my folks who are retired. Far northern Wisconsin. SIP panel house, 2" of spray foam on basement walls, Foamed rim joist, 2" of foam on the backside of the ceiling sheetrock, and 14" of cellulose on top of that. Low-E double pane windows. I'm getting two trains of thought here. One is to put in a 40,000 BTU 2 speed furnace 96 AFUE but i have a few people telling me i should put a 60,000 2 speed BTU in. My biggest fear is the 60,000 short cycling being the heat loss has been calculated out at 33,309 BTU. An HRV is also being installed.


Here is the REScheck .

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  • Jamie Hall
    Jamie Hall Member Posts: 23,426
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    If you've calculated that heat load correctly, you've answered your own question. Bigger isn't always better.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Rich_49
  • hot_rod
    hot_rod Member Posts: 22,251
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    Are those input or output btu/hr numbers for the furnaces.

    Are they 90% furnace? So 40k input X 90%= 36,000 output, that would cover a 33,000 load
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,613
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    @mjstef

    You had a good heat loss done. trust the numbers. As long as you put a furnace in whose output is more than the heat loss you are fine. There is no good reason to install anything larger.
    PC7060
  • hot_rod
    hot_rod Member Posts: 22,251
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    @mjstef

    You had a good heat loss done. trust the numbers. As long as you put a furnace in whose output is more than the heat loss you are fine. There is no good reason to install anything larger.

    I suspect there is some fudge factor in the heat load programs also.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    PC7060Rich_49