Heat pump compressor cut out at what temperature

Discussion in 'Workshop and Home Improvement' started by Living in the Past, Dec 21, 2010.

  1. Living in the Past

    Living in the Past SILVER Star

    Messages:
    9,215
    Looking for some input on what temperature I should cut the compressor off and just run the strips on a heat pump.

    Little back ground. This is for my cabin in Northern Arizona at 7,000'. I heat the cabin with a wood stove while I'm there but have a electric furnace now that I keep set at 45 degrees. Bought a heat pump so I could have cooling for the warm afternoons during the summer. The plan is to use the heat pump to keep the cabin at 45 degrees while I'm not there. So I'm am not concerned about the temperature coming out the vents just keeping the cabin at 45. So what would be a good temperature to wire in a stat to cut the compressor and move the electric strips up to first stage. The outdoor unit will be next to the cabin in a area that should get to deep in snow. yes we do get snow in AZ.

    I have had a opinion that I can't use a heat pump with it set at 45 degrees. I can't see how this could could be true. The closer the inside and outside are to each other the easier the heat transfer.
  2. Trollhole

    Trollhole THC Moderator Supporting Vendor

    Messages:
    18,910
    Location:
    Mauldin, SC
    You don't want to cut the heat pump off and run on strips alone. Get ready for a big bill even at 45 degrees. I would set the heat pump up normally and have the heat strips kick on when the heat pump cannot keep up.

    In the south I tell people to switch over from heat pump to gas around 28-32. Depending on seer rating. But if they strictly have a heat pump sysytem and strips I tell them to run that heat pump and let the strips do the keeping up.
  3. Living in the Past

    Living in the Past SILVER Star

    Messages:
    9,215
    Thanks for the reply. This is my trade or at least it used to be before getting a goverment job. I do remember there was a cut off point that for the amount of heat transfer and what the compressor was costing to run it was cheaper to just use heat strips. Remember that being in the mid twenties. You are the first person who has had the same mind set as myself. Everyone else is saying around 45 degrees. If I was trying to heat it for comfort I can understand their mind set a little better. Right now I only have a electric furnace but only using it to maintain 45 degrees when I'm not there really isn't to bad. It was when I first bought the place and didn't have wood burning stove it was costing a arm and leg. I will be using a multi stage stat. But I will still need a heat pump shut off. We have already had sub zero weather at night. What I really need is a way to use the heat pump to keep the space warmer and then let it cool down at night so the strips would run as much:hmm: The only problem is when we have really cold days I will using the heat strips instead of the heat pump. What I could do is use a outdoor stat which would switch to a different thermostat with a lower setting when temperature drops outside:idea:

    Any thoughts on this?
  4. not sure of the seer rating of mine, i had oil back up and it is disconnected, the heat-pump alone does well down to 40* after that it keeps going into defrost mode, which seems to run the electric bill up.
  5. Living in the Past

    Living in the Past SILVER Star

    Messages:
    9,215

    Good point. Lower the temperature the closer the dew point. Closer the dew point the more it's going to go thru defrost. Since all I have know is a electric furnace using a heat pump anytime should help. I bought this unit mainly to get Air Conditioning. I bought it cheap since it was a R22 unit and only 13 SEER.
  6. i could be wrong here, i am not an hvac guy, but you should be able to have your heat pump run till a certain temp then have the electric furnace for Emergency, or backup kick on till the temp gets back up.

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