Economic Balance Point for Heat Pump
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  1. #1
    Join Date
    Dec 2005
    Posts
    40
    I used the "search" function at this site and it appears this topic hasn't been covered....

    so, does anyone know if an economic balance point calculator exists somewhere on the internet? I'd like to calculate at what indoor temperature I should switch my heat pump to gas furnace given a set of fuel and electric costs, heat pump and furnace size, and conditioned square foot. I'm not concerned with super accuracy, I'd just like a ball park..thanks.

  2. #2
    Join Date
    Nov 2001
    Posts
    1,874
    I'm sure you mean at what outdoor temp should you switch to gas.

    That depends on your house load requirements, the region in which you live. And the Eff of your H/P. And some on how well you feel with 85* air coming from your vents instead of 110* air.

    I tend to set younger peoples setpoint alittle lower, they can stand cooler supply temps better then someone older.
    I may set theirs about 25*, and set an older customer at about 35*. Their comfort has to plan a small roll.
    If you try to fail, and succeed.
    Which have you done ?



  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,884
    http://www.warmair.com/html/fuel_cost_comparisons.htm

    not automatic but you can figure it out


    Right now it is 20 here and I have the pump running.

    figuring my pump at COP of 2 and 4 cent juice
    and gas at $1.00 CCF and 80% furnace

    I'm looking at 59 cents for the pump or $1.21 for natural gas. So I'll leave the pump on, it's holding steady at 65 in which is just about right for snooooozing.

    With our extremely low juice rates, the pump is probably cheaper down to 0 but any colder than 20 and it won't hold my mid 60s.

  4. #4
    Join Date
    Dec 2005
    Posts
    40
    Thanks. That's what I figured. I've currently got my gas furnace effectively "locked out" and it only comes on when the indoor t-stat senses the Heat Pump cannot keep up with the temperature (currently 68 degrees). It got down to 5 degrees here in central ohio last night and my heat pump provided 75% of the needed heat after it got below 12 degrees (gas kicked on about once an hour for 5 minutes for the entire time it was below 12 degrees); above 12 degrees it provided all I needed. Bottom line, I figure "locking out" my gas furnace unless the Heat Pump can't keep up is the correct decision. Thanks for the location of the calculator. -G

  5. #5
    Join Date
    Jun 2003
    Location
    Jacksonville, FL.
    Posts
    4,313
    The balance point is that point at which time the heat pump can no longer keep up with the heat loss & must begin using the second stage heat to help it out. In other words, it's all relative, Dude!
    WHY?

  6. #6
    Join Date
    Apr 2004
    Posts
    7,680
    Sharp, mine is set up the same way, 2nd stage brings on my furnace. My heat pump has kept the house at set point down into the teens. Hey, if I get a chill, I can always switch it to emergency heat for a while.

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