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  1. #1

    heat pump emergency heat?

    I bought a house last year and it uses a heat pump the AC worked fine in the summer from the heat pump now it has cooled off. Last night it was 39F and the house temp just kept droping as the heta pump just ran and ran so i switced it over to emergency heatand the house warmed right up. I thought you should only have to use emergency heat when it was really cold outside doing a google search i see differant answers some say below 39F turn emergency heat on and other says colder.

    emergency heat is fine but it's so costly as i understand it is like using baseboard heat not that efficient at all.

    Is it better to let the heat pump run and run when its 39f out? The house temp was not going up, i guess it could not pull any heat from the air outside.

    I had installed a touch thermostat should it switch to emergency heat automatically? I can just see it runin and runin all day while im at work and not warming the house up.

    It is a new unit so im sure it is working fine it's just does this somedays.

  2. #2
    Join Date
    Apr 2002
    Location
    USA
    Posts
    5,783
    What is the temp of the air coming out of the vents.
    Get a temp gauge and measure it.
    Might not be working properly.

  3. #3
    Join Date
    Oct 2009
    Posts
    865
    Try closing the window.

    Seriously, heat pumps drop in efficiency the colder it is outside. They are typically designed for a given outside temperature range, so if you bought one that wasn't designed for the temperatures in your region, it might not be working optimally. Or, it could just be defect.

  4. #4
    Join Date
    Mar 2003
    Location
    United States
    Posts
    3,683
    Sounds like it might be freezing up; does the actual unit look frozen? My parents had a really old pump that started doing this. Basically it will begin to freeze around 40 degrees F and then they had to go to emergency heat.

  5. #5
    Join Date
    Jul 2009
    Location
    NC
    Posts
    938
    There is only so much a heat pump (or AC) can do. Depending on the size (BTUs), type of refrigerant and technologies employed (hot gas recirc, etc.). There is a maximum differential that can be acheived - there are only so many BTUs of heat that can be transferred in either direction.

    It sounds like it is a basic unit that MAY be a bit under-sized for your house. WAY too many factors to say deffinately.

    The touch thermostat may or may not be "smart" enough to recognize that the heat pump cannot keep up with the demand and automatically switch to backup heat. The simplest one that would do that would need an outdoor temperature sensor. It would determine if CallForHeat = true AND OutdoorTemp < {Adjustable X} then BackupHeat = true.

    There are more sofisticated control strageties.

    HTH

    [I do programming for commercial HVAC building automation systems ]
    ☆☆☆ Cool Domain Names - DomainSale.link☆☆☆

  6. #6
    Quote Originally Posted by Techark View Post
    What is the temp of the air coming out of the vents.
    Get a temp gauge and measure it.
    Might not be working properly.
    I'm not at home so I can not check but I would assume below 61f.

    That's what the house was down to before I turned the emergency heat on. I only keep it 66f in the house.

    The heat pump was matched for the square feet of the house so it should be anough.

  7. #7
    Join Date
    Jul 2004
    Location
    Memphis, TN
    Posts
    1,225
    Mine usually switches over to emergency heat around 38 or so.

    Once it starts getting close to that temp, the air blowing out of the vents isn't that warm..I've never measured it, but if I had to guess...probably 65 degrees coming out of the vents.

    I've never noticed that big of an increase in my utility bills when I've used the emergency mode.

  8. #8
    [QUOTE=cheyenne1212;6491701]Mine usually switches over to emergency heat around 38 or so.

    Once it starts getting close to that temp, the air blowing out of the vents isn't that warm..I've never measured it, but if I had to guess...probably 65 degrees coming out of the vents.


    Is yours switching over to emergency heat automacilly?

    I,ve seen it heat the house when it's been below 32f but the other night it was only 38f and was not heating the house?

    It must have something to do with what's in the air then maybe the amount of water etc

  9. #9
    Join Date
    Jul 2004
    Location
    Memphis, TN
    Posts
    1,225
    Honestly, I'm not sure.

    I know my programmable thermostat..switched it for me I do believe..but I put in a new non programmable thermostat, and I believe I have to switch that one manually.

  10. #10
    How long do heatpumps usally have a warranty for? It's less than 3 yrs old i think. It's a Miller brand but the inside heater part is made by intertherm and says. The duct system can handle 47,800 bts an hour and not go over it because it can cause extra moisture etc.

    This thing is really getting on my nerves. It will run all night to keep it in the mid 60s in the house that can't be very energy efficient, i can turn the emergency heat on and it will heat it up in 30min or less.

    BTW i get 95F air coming out of the vent when the emergency heat is on and when the heat pump is used 64F and of course thats the temp of the house as well. The heat pump keeps the house cool in the summer but in winter we freeze.

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