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  1. #1

    Heat Pump auxiliary / emergency question

    I live in a one-story 1400 sq ft home with a Trane 2.5 ton heat pump. Summer cooling bills are reasonable, ~$175, but in the winter my heating bills are well over $400!

    It is a single-stage air heat pump with two-stage auxiliary / emergency resistance heating elements in the furnace. The furnace has two breakers on the side of it, one 40amps and the other 60amps, which I am assuming feed the heating elements.

    In winter I notice that even when it's not that cold out, as I "dial up" the thermostat's temperature setting, that I will hear the heat pump unit come on, and if I go just one degree higher the aux heat kicks in. I understand the aux heat is needed on really cold days, but this happens even in the 40s.

    The electric bills have been so high I've been tempted to trip one of the aux units breakers just to see if it helps, but I don't really know what I'm doing.

    My questions are:
    - is this normal behavior?
    - in an area with avg January temp 25, avg July temp 75 (central Indiana) should heating costs be two-and-a-half times the cooling cost?
    - do I just need a better thermostat?
    - do they even make programmable thermostats for this setup?

    I really need some advice, my heating bills are eating me alive.

  2. #2
    Join Date
    Aug 2008
    Posts
    416

    Moving Thermostat Setting w/Heat Pump

    Are you "manually" adjusting your thermostat setting during the day as you come and go??? If so stop... Moving the thermostat setting manually will cause the backup/emergency heat to kick on and use the juice. Heat pumps should be set and forget or you need a programmable t-stat designed for heat pumps that will slowly bring the heat up to avoid using the electric backup.

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,060
    Answers:

    1. Yes, when you turn up the stat more than a degree it does ask the backup for help. Best bet with a heat pump in heating season is set & leave alone.

    2. Hard to say since your bill also has everything else electric on it. In the winter, there is more light usage due to short days. Incoming water is much colder so the water heater works harder. From co-workers who are all electric, 2.5 x summer bills probably isn't out of line.

    3. If you have an old mechanical stat, changing to a good electronic stat is smart.

    4. Yes, there are programmable stats but in the winter, unless it is very mild, they could cost you more than leaving alone due to backup use during the warmup.

  4. #4
    Join Date
    Jul 2002
    Location
    Zelienople, Pa
    Posts
    2,965
    I've seen situations like this where the cooling and strip heat running at the same time during the call for heat...
    How tall are you Private???!!!!

  5. #5
    Join Date
    Feb 2009
    Location
    Portland OR
    Posts
    1,977
    Have you had a pro come out and do your maintenance? You might have a clogged coil or your unit may not be running as efficiently as possible. Of course all the other solutions listed are good ones too but I would highly recommend a tune up if you have not had one in the past year.

    What model of heat pump do you have?

  6. #6
    Join Date
    Mar 2011
    Location
    Edna Bay, Alaska Highest concentration of black bears in the US
    Posts
    623
    Quote Originally Posted by Gunnery Sergeant Hartman View Post
    I've seen situations like this where the cooling and strip heat running at the same time during the call for heat...
    what he said.

  7. #7
    Join Date
    Feb 2009
    Location
    Portland OR
    Posts
    1,977
    Quote Originally Posted by Dr.phil View Post
    what he said.
    Are you both talking about a defrost cycle? Because they said his coolings bills are 175 and heating bills are 2.5-3 times that so I doubt its running in AC with strip heat unless he is running into defrost because they are going to 25 degrees and below in their area. Seems like its a possible user error/possible bad thermostat settings(probably need a stat with outdoor temperature sensor for aux heat lockout is how we install our systems here) possible old/going bad unit.

  8. #8
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Might be worth looking at getting a thermostat with an outdoor temperature sensor to lock-out the auxillary heat strips above a certain temperature. That temperature would be dependant on a load calculation and unit size... and inside temperature. I think it's usually around 30-35F. But if you're willing to have the house be just a little cool, you could set it lower.


    Remember, the heat pump get more effecient and puts out more capacity the lower the indoor termperature setpoint is. So living with the house just 1 degree cooler can make a significant difference.

    Like thers have said... don't use any setbacks with a heat pump... unless it's a dual fuel set-up with a outdoor temprature sensor and auxllary lock-out.

  9. #9
    Join Date
    May 2004
    Location
    Frederick, MD
    Posts
    949

    Have a

    company give you a quote for a new t-stat that is compatible with outdoor sensor and lock-out and will work with your system. If you bump up the stat more than 1 or so degrees and the OD temp is above setpoint, the aux heat won't come on. I have an outdoor thermostat kit (no longer available) with 2 settings. I set the first stage of heat only to come on when the OD temp was below 25, and the second stage when the OD temp was at 5 degrees.

  10. #10
    Join Date
    Feb 2009
    Location
    Portland OR
    Posts
    1,977
    Quote Originally Posted by motoguy128 View Post

    Remember, the heat pump get more effecient and puts out more capacity the lower the indoor termperature setpoint is. So living with the house just 1 degree cooler can make a significant difference.
    I have heard that a 1 degree difference is typically about a 6% savings. So if your spending $400 on heating(and im sure that $400 bill has lights and other devices but for my math we will use $400)
    $400 at 70 degrees
    $376 at 69 degrees
    $353 at 68 degrees
    $332 at 67 degrees
    $312 at 66 degrees
    $293 at 65 degrees

    So a 5 degree change in settings can cut your bills by 25%, I think for $100 a month i might put on more clothes, it sure would buy a lot more clothes.

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