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  1. #1

    Confused Heat pump sizing

    I'm in the process of going to a geothermal system and I've got a problem. I have 2 proposals from contractors that seem to be at odds with each other.
    The first contractor's heat analysis came up with a heat loss of 81400 BTU and proposed a 3 ton single stage system. The second has a heat loss of 67000 BTU and proposed a 2 stage 5 ton system.
    After the analysis is done is it a simple matter of replacing the total BTU heat loss with the appropriate amount of heat pump BTUs be it from the groundwater system and/or kw heat?
    If so, in the first example,with an 81400 BTU loss and a 36000 BTU heat pump am I going to die cold?

    I'm at a loss so any explanation will be appreciated.

    Dave

  2. #2
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    Quote Originally Posted by dogoodman View Post
    ?
    If so, in the first example,with an 81400 BTU loss and a 36000 BTU heat pump am I going to die cold?
    Dave
    Dave

    what is cooling load?

    to answer your question, you will be cold or else have an extraordinarily high electric bill due to the neccessity of large KW backup heat strips defeating the purpose of geo.

    something not correct here!

    IMO

  3. #3
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    Quote Originally Posted by tigerdunes View Post
    Dave

    what is cooling load?

    to answer your question, you will be cold or else have an extraordinarily high electric bill due to the neccessity of large KW backup heat strips defeating the purpose of geo.

    something not correct here!

    IMO
    How do you figure that.
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  4. #4
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    so beenthere

    help dogoodman and myself out.

    what are we missing?


  5. #5
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    Its a geo.
    Without knowing what the specs are on it, if his loss is 81,400 he may need 3, 5, 7.5, or 10 KW strip.
    They heat better then they cool.

    Your telling him something is wrong, about a unit you know nothing about its specs. And I'm guessing not a lot about geos at all.
    And that contractor may be dead on right with all his sizing.
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  6. #6
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    Pull up a 3 ton geo from ARI, and look at its performance.
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  7. #7
    Hello,

    The cooling load is 31641.

    He doesn't have the kw listed but in casual conversation I think he said 10-15 kw.


    Thanks,


    Dave

  8. #8
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    Quote Originally Posted by beenthere View Post
    Pull up a 3 ton geo from ARI, and look at its performance.
    I looked in the Direct Geo Exhange of the ARI site. I didn't see what you are getting at. Help me understand, Uncle BeenThere.

    Thanx.

  9. #9
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    Look at the specs of YOUR HP at 50 plus degrees OD temp. The water temp for his geo could be 45, 55, or more.

    So even at 20 degrees OD temp, he is getting more heat then your HP does at 47* OD.

    Sizing the strips to take care of all or most of the load incase of HP failure is a smart thing to do.

    Without knowing what the specs of the geo are, saying something is wrong is pathetic.
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  10. #10
    Here's a little more info:

    He's specing a 15 kw heat strip on a FHP model GS036, two stage.
    Closed loop, central Michigan area.
    120 year old brick farmhouse R-50 attic, approximately r-10 wall cavity foam.

    Thanks for the help so far,



    Dave

  11. #11
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    Quote Originally Posted by beenthere View Post
    Look at the specs of YOUR HP at 50 plus degrees OD temp. The water temp for his geo could be 45, 55, or more.
    I get a full 3-tons at 50F outside.


    Quote Originally Posted by beenthere View Post
    So even at 20 degrees OD temp, he is getting more heat then your HP does at 47* OD.
    Because the geo water temp is much warmer than the 20F outside air temp - got it.



    Quote Originally Posted by beenthere View Post
    Without knowing what the specs of the geo are, saying something is wrong is pathetic.
    That wasn't me (although my wife has called me pathetic before, it wasn't HVAC related).

    Take care.

  12. #12
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    And that is not a direct geo HP.
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  13. #13
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    Quote Originally Posted by gary_g View Post
    I get a full 3-tons at 50F outside.

    Thats low for a HP

    Because the geo water temp is much warmer than the 20F outside air temp - got it.

    Yep.

    That wasn't me (although my wife has called me pathetic before, it wasn't HVAC related).

    Didn't say it was you.
    If Infinite possibilities provides infinite opportunities, wall do infinite walls provide.
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