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-   -   Replacing honeywell stat to an other honeywell stat (https://www.askmehelpdesk.com/showthread.php?t=292044)

  • Dec 14, 2008, 01:27 PM
    JohnHemingway
    Replacing honeywell stat to an other honeywell stat
    I'm switching my old stat to a new one that lets me enter a program.

    I have an electric central air furnace and a thermopump outside that provides heat and AC.

    I'm going from a honeywell CT3600 or so (looks the same as in the manual for that one but without the program buttons) to a RTH8500.

    I have 6 wires coming out of the wall and here are how they were plugged:

    Green - G
    Red - R
    Blue - C
    Orange - O/B
    Yellow - W1 and jumped to Y1
    White - W2 and jumped to E

    My question is that on the old stat W1 is jumped with Y1 and W2 is jumped with E which means that according to the new stat I would be putting both the yellow (W1 and Y1) and the orange (O/B) in the same terminal.

    How should I wire it and where should I put jumpers?
  • Dec 14, 2008, 01:30 PM
    hvacservicetech_07

    Are the terminals on the new thermostat the same?
  • Dec 14, 2008, 01:38 PM
    JohnHemingway

    The new stat has one terminal that is W and O/B with W being the conventional and O/B on the heatpump side
  • Dec 14, 2008, 01:40 PM
    hvacservicetech_07

    Just w, no w2?
  • Dec 14, 2008, 01:44 PM
    hvacservicetech_07

    Green wire-G
    White wire- w with a jumper to E
    Yellow-y
    Orange-o/b
    Blue-C (common)
    Red-R
  • Dec 14, 2008, 01:46 PM
    JohnHemingway

    Yew the terminal is marked W on the conventional side and O/B on the heat pump side. W2 for the conventional is on the aux terminal for the heat pump.

    http://hvactroubleshooters.com/HONEY...%20INSTALL.pdf

    On page 10 there is a nice diagram of how the new base's terminals look like
  • Dec 14, 2008, 01:50 PM
    hvacservicetech_07

    Ok, the W terminal is also O/B (reversing valve). You're orange wire will go on that terminal,you can jumper y and w if you want. Wire it the way I listed above. Also jumper w2 and E together.
  • Dec 14, 2008, 01:58 PM
    JohnHemingway
    So that means I will have the following

    R - red
    C - blue
    G - green
    W, O/B - white with a jumper to E
    Orange
    Y - yellow

    I can jump Y and W which means on the W, O/B terminal I would end up with white, orange and yellow all being jumped with Y and E
  • Dec 14, 2008, 02:01 PM
    hvacservicetech_07

    No, the jumper goes between w and y, w2 and E. White wire will go to w2 and yellow to y, orange to w..
  • Dec 14, 2008, 02:05 PM
    hvacservicetech_07
    Blue-C
    Yellow-y with jumper to w
    Orange-W
    White-W2 with jumper to E
    Red-R
    Green-G
  • Dec 14, 2008, 02:06 PM
    JohnHemingway

    Final result would be (making sure I understand before I blow the new stat):

    G, R, C in their respective terminals
    White wire - E jumped to the aux, W2 terminal
    Orange and yellow wires to the Y jumped to the W, O/B terminal
  • Dec 14, 2008, 02:09 PM
    hvacservicetech_07

    Correct. Be sure to shut the power off to the system and double check you're work before restoring the power.
  • Dec 14, 2008, 02:10 PM
    hvacservicetech_07
    That thermostat may require an installer setup,should be instructions in the book.
  • Dec 14, 2008, 02:12 PM
    hvacservicetech_07

    Post back and let me know that everything worked OK, or if you have any problems.
  • Dec 14, 2008, 02:23 PM
    JohnHemingway

    Heatpump switched on but it feels pretty cold. Letting it run to see if it's AC or heat.

    On the old stat I would have to switch between heat for the heatpump and emergency heat for the furnace depending on how cold it was outside. Now the new stat list the available systems and I only have heat and AC as options. Will the new stat know when to switch to the furnace?
  • Dec 14, 2008, 02:29 PM
    hvacservicetech_07

    You will need to set that up. This stat can be used as an heat pump or conventional, you are probably just running straight a/c right now.
  • Dec 14, 2008, 02:34 PM
    hvacservicetech_07

    Go into the installer setup and select you're system type.
  • Dec 14, 2008, 02:48 PM
    JohnHemingway

    Looking at the list of options on page 18 of: http://hvactroubleshooters.com/HONEY...%20INSTALL.pdf

    I chose option 9 for my system which includes a furnace inside and a heatpump that can also do AC outside
  • Dec 14, 2008, 02:52 PM
    JohnHemingway
    If I should chose option 7 then when it asks me whether I have a heating or cooling changeover valve which do I enter? Try one and if it's blowing AC chose the other?
  • Dec 14, 2008, 03:34 PM
    hvacservicetech_07

    Yes, you have a reversing valve.

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