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  1. #1
    Join Date
    Sep 2011
    Location
    Nj and Delaware
    Posts
    75

    Heat Pump: Winter Setback Temperature

    Looking ahead to cooler weather this winter, and a question.

    We have a second home in Southern Delaware that has a 2stage Goodman heat pump with electric backup. This place is mostly vacant in the winter so we turn down the heat while not there. We visit for a week or so every 2 or 3 weeks.

    We can control the thermostat remotely and there is an outside temperature sensor that locks out the electric strips above 25*

    I understand that when occupied we should keep the house temperature relatively constant temperature to maximize efficiency.

    So the question, is there any minimum setback temperature for the house when we are not there to avoid equipment damage, or other issues? Recovery time is not an issue as I can start warming up the place remotely.

  2. #2
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,512
    in my area there are plenty of 2nd houses that the tstat is set at 50 and the heat pumps seem to do fine i would be careful about locking the strips out to low because if the pump breaks you want the auxillary heat to stop the pipes from freezing
    We really need change now

  3. #3
    Join Date
    Sep 2011
    Location
    Nj and Delaware
    Posts
    75
    Good point about the strip's lockout temp. I can receive a text alarm from the Honeywell/ComfortNet stat if the inside temperature drops below x degrees. At that alarm, I should be able to remotely either turn on Emergency Heat or if that fails, it is only a 5 hour drive to the place for me or a 20 minute ride, depending on workload, for a service call from the local HVAC company.

    So there is no issue with the "A coil" seeing 50* air and sending that cold R410 back to the outdoor unit?

  4. #4
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,512
    i have not seen any issues other than the defrost times
    We really need change now

  5. #5
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    5,994
    With t-stat set to 50'F ( 72'F normal), one has already reduced heat pump electric use ~ 35%.

    What is the cost-benefit of any lower temperature ?
    I believe there is HIGH R I S K of pipe freezing for hundreds of hours at < 30'F
    if the t-stat is set lower.

    I doubt that setting heat strips to 25'F lock out presents a risk of maintaining 50'F.
    Designer Dan
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    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,803
    Don't set it lower then 50. Not good for the heat pump. And it will cause excessive defrost cycles.
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  7. #7
    Join Date
    Sep 2011
    Location
    Nj and Delaware
    Posts
    75
    Thanks to all who responded. So it sounds like 50* is a good target for winter setback.
    The climate there is not too extreme, compared to some areas. Typically I have measured a minimum temp of about 15* one or two nights, so the danger of freezing up the place exists, but probably not too realistic. Additionally all the water pipes are run on inside walls so they would stay fairly warm for quite a while.

    The challenge will be to find a recovery schedule that gets the place warmed and toasty when we walk in the door without running the 10kW strips too much. I know the ComfortNet thermostat has a bunch of options where a temperature differential can be set to control the strips, and HP staging. Currently I am set up for "comfort" as I just leave the unit at 70* most of the time when we are there.

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