Results 1 to 8 of 8
  1. #1
    Join Date
    Feb 2005
    Posts
    39

    Question

    I need 42,000 btu for heating, the specs on my unit says is will produce 29,700 btu@47 degrees and 17,600 @17 degrees. Will I ever be able to reach 72 degrees without back up heat?

  2. #2
    it depends on the place u live? I dont think u want to undersize a ?

  3. #3
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    probably reach 72F when 65F outside --

    so, insulate, caulk, --- +

  4. #4
    Join Date
    Sep 2004
    Posts
    3,157
    It will heat a dog house to 72 degrees , well a small dog house----but not when its below zero----

  5. #5
    Join Date
    Apr 2004
    Posts
    7,680
    Whats the temp that you need 42,000? Is that zero or -5 degrees? Heat pumps are sized for cooling. My guess until I see an answer is yes you will need aux heat but you should have a fairly low balance point.

    Whats your load calc say you need for heat at 47? Whats your load calc say you need for 17?

  6. #6
    Join Date
    Feb 2005
    Posts
    39
    I'm new to this HVAC stuff, what is a balance point?
    Do they size the unit to a outside tempature?

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,366
    Balance point is the outdoor temp that if the temp gets any lower the heat pump won't provide enough heat by itseld to heat the house.
    So you will need some back up heat.

    Yout heat pump is sized for the cooling load, not heating load.
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  8. #8
    Join Date
    Apr 2004
    Posts
    7,680
    Your 42,000 is the total amount of heat needed when its at the coldest outside, lets say 0 degrees depending on where you live. This is the amount of electric heat needed as back up heat. The balance point is the point where the amount of heat loss from the structure equals the amount of heating capacity from your heat pump without the electric heat. Any lower and the aux heat will need to cycle on occasionally and supliment the difference.

    More often than not you will be above the balance point as it generally doesnt stay that cold for weeks on end. If you are however in Alaska or Canada, that may not be the case.

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