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  1. #1

    T-Stat with outdoor sensor

    I have a 4 ton heat pump unit along with a back-up propane furnace. I have recently had to have the compressor replaced in the outside unit. I have been through 4 or 5 contactors in the past couple of years as well. HVAC technician has previously said that the problem lies with the outdoor thermostat/dual fuel kit mounted inside the heat pump. (It gets too much condensation. I live in southern VA wher it can get pretty humid.) I have replaced the outdoor heat pump t-stat twice and all is well for a while, then it starts to act up again and makes the contactor "chatter" and eventually fail. To try and remedy this, I purchased an indoor programmable t-stat with a wired outdoor sensor. It is dual fuel and 3 heat 2 cool capable.
    My question is: After wiring the new t-stat in the same way as the previous one with the addition of the 3 wires for the outdoor sensor, how do I properly disconnect the outdoor heat pump t-stat with the dial on it? I have enabled the outdoor sensor in the menu and believe I have all the settings correct, but the new t-stat is still energizing either the heat pump or furnace, based on outside temperature taken from the old dual fuel kit. If I disconnect the old t-stat in the heat pump it blows the fuse in my furnace. Is there a wire going to the inside t-stat that I no longer need? Do I need to run any additional wires from my furnace to the inside t-stat? I want to be able to control everything from my new t-stat. Everything is working properly right now, but is is basically the same as what I had before, just a new inside thermostat.
    Hope all of this makes sense.
    Thank you.

  2. #2
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,975
    All the old controls need to be removed and disconnected.

  3. #3
    thanks, but when you say old controls, are you referring to just the old outdoor heat pump t-stat or is there more to the dual fuel kit? When i disconnect the 3 wires going to the t-stat in the hp(red, blue & yellow), the heat pump will not run. Is there a circuit board or something else? The yellow wire from the hp t-stat runs to what looks like a relay in the hp and the blue and red wires run into the house. I am thinking that I don't need one of the wires running to the new indoor thermostat that may be connected to the outside dual fuel kit? I am considering having a hvac technician come out, but thought that if it was something as simple as disconnecting something, I could do it myself. I have a good understanding of the hvac system, but am not an expert.
    Thanks.
    Last edited by VAhome; 10-29-2012 at 09:57 PM.

  4. #4
    Join Date
    Oct 2012
    Location
    Corryton,TN
    Posts
    69
    It's hard for us to say fRom here you should call someone

  5. #5
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,851

  6. #6
    Join Date
    Oct 2012
    Location
    Corryton,TN
    Posts
    69
    why do you tell me this again? i read them and i gave good advice that would not endanger the home owner?
    Quote Originally Posted by jpsmith1cm View Post
    buzhall

    Please review AOP Forum rules here.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,540
    Quote Originally Posted by buzhall View Post
    why do you tell me this again? i read them and i gave good advice that would not endanger the home owner?
    Your not a Pro * member. You are not allowed to post in the AOP forums.

    From the AOP rules.
    THE ONLY PEOPLE allowed to REPLY in the Owner Assistance Forums will be a Pro Member with a * by their user title and the one who started the thread. No others may post a reply.

    This area WILL be monitored by the AOP (Ask Our Pro's Committee). Be advised that the AOPC will have full authority over the Owner Assistance Forums. Warnings will be issued for those posting advice that are not approved to do so. Continued violations will result in infractions being issued along with more harsh action if warnings are not heeded.
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    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,602
    This sounds like a DIY project. We can't assist you with this. Sorry. You'll need to call a competent HVAC service technician.

    If you feel that none are competent in your area, then completely rewire the system using the wiring diagrams furnished with your new thermostat aligned with the diagrams furnished with your furnace omitting the un-used dual fuel kit. Good luck.

  9. #9
    Join Date
    Oct 2012
    Location
    Corryton,TN
    Posts
    69

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