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  1. #1
    Join Date
    Jan 2020
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    Raleigh, NC
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    Aux heat only on heat pump

    Hello all.
    I'm not looking for a diy answer, just trying to understand my heat pumps operation because I will have a HVAC professional do any work needed. I have a Trane xe 1100 condenser and an american standard air handler with electric heat strips (TWH024B140A1). This unit is a 1993 model. (it's old, I know.) When the system is calling for cool, all systems work properly; i.e. condenser (fan and compressor) are running and the air handler runs. However, when the tstat calls for heat, only the air handler and electric heat strips come on. The condenser does not operate at all. I have looked up the thermostat the previous owner installed and the manual says it is not to be used with Heat Pumps that have back up heat (RTH221b1021). With this knowledge, I have a few questions.
    1. Since the tstat appears to be wrong for the system, would it only be sending the single to the air handler to run during heat and not sending the signal to the condenser?
    2. Could there possible be another part in the condenser that has locked out the heat operation? Everything runs in cool.

    Thanks for your time.

    JLock126

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    If you aren't using a HP stat, that's the problem. It does not ask for the outdoor unit to come on for heat, only the backup. Have a tech put on the right stat and check the system over. It is rather long in the tooth for a heat pump but it is a Trane.

  3. #3
    Join Date
    Jan 2020
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    Raleigh, NC
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    Thread Starter
    Quote Originally Posted by BaldLoonie View Post
    If you aren't using a HP stat, that's the problem. It does not ask for the outdoor unit to come on for heat, only the backup. Have a tech put on the right stat and check the system over. It is rather long in the tooth for a heat pump but it is a Trane.
    Thanks BladLoonie. I'm going to make the call to have the tstat changed out by a HVAC pro. I have a Honeywell Pro 3000 left over from an previous job but I'm unsure of the wiring at the tstat since the previous owner has installed the wrong tstat currently and I have no manuals or wiring diagrams for the system. I've done my best to trace the wiring down and it appears the wiring to the AHU and out to the condenser are correct. Here's hoping that a new tstat solves my issue. All other components seem to be in working order. Fingers crossed.

  4. #4
    Join Date
    Sep 2007
    Location
    edmonds wa
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    4,434
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    Get a good stat, some utility providers offer rebates. Stay away from Nest, my choice is honeywell, all i have ever had for my own use.
    UA Local 32 retired as of Jan 2020

  5. #5
    Join Date
    Jan 2020
    Location
    Raleigh, NC
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    Thread Starter
    Quote Originally Posted by buford View Post
    Get a good stat, some utility providers offer rebates. Stay away from Nest, my choice is honeywell, all i have ever had for my own use.
    Thanks, will do. I will have the HVAC tech out, hopefully, soon to replace it. A friend gave me a Nest to put in another house but I'm not brave enough to have it installed because everything works just fine there.

  6. #6
    Join Date
    Jun 2014
    Location
    Dover, DE
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    Just remember, simple is better with a heat pump. The “energy saver” type thermostats that set the temperature back when your not home can actually increase your electric bill by using the electric heat more often.
    The system will be happiest when left to a constant setpoint.
    Because every time the electric heat strip comes on your electric bill goes up.
    “I haven’t failed. I’ve just found 10,000 ways that won’t work.” - Thomas Edison

    “It’s not whether you get knocked down, it’s whether you get up.” - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

    Local 486 Instructor & Service Technician

  7. #7
    Join Date
    Jan 2020
    Location
    Raleigh, NC
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    Thread Starter
    Quote Originally Posted by rider77 View Post
    Just remember, simple is better with a heat pump. The “energy saver” type thermostats that set the temperature back when your not home can actually increase your electric bill by using the electric heat more often.
    The system will be happiest when left to a constant setpoint.
    Because every time the electric heat strip comes on your electric bill goes up.
    I read that recently on this forum and had never considered that before. Very sound advice. Thanks

  8. #8
    Join Date
    Jan 2020
    Location
    Raleigh, NC
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    Thread Starter
    Quote Originally Posted by rider77 View Post
    Just remember, simple is better with a heat pump. The “energy saver” type thermostats that set the temperature back when your not home can actually increase your electric bill by using the electric heat more often.
    The system will be happiest when left to a constant setpoint.
    Because every time the electric heat strip comes on your electric bill goes up.
    I read that recently on this forum and had never considered that before. Very sound advice. Thanks

  9. #9
    Join Date
    Jan 2020
    Location
    Raleigh, NC
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    Thread Starter
    Update: HVAC Tech installed the new thermostat and everything fired right up. Thanks for all the advice.

  10. Likes beenthere liked this post.
  11. #10
    Join Date
    Oct 2006
    Location
    The Beach
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    Good for you. Stay warm
    Blue Fox

  12. #11
    Join Date
    Oct 2002
    Location
    Plano, TX
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    Just saying. It has been a long time since I have seen a thermostat NOT work with heatpump. Most all do.

  13. #12
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    Lotta low end stats aren't designed for a pump. Got one on my desk, Emerson 1F86-0244, our basic non programmable. Probably would be wise to switch to a HP model but that adds bucks.

  14. #13
    Join Date
    Oct 2002
    Location
    Plano, TX
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    1f86-0244 is HP stat

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