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chiefward's avatar
chiefward
Explorer
Oct 01, 2015

Replacing Duo therm thermostat, need help.

I want to replace my analog thermostat with a Hunter model 42999 digital thermostat but the wiring colors are different. My Duo therm has, red, yellow, white, blue, orange, green. The hunter has terminals for Green, white, yellow, redh & redc with jumper. Watching several YouTube videos only confused me. One reviewer stated the hunter would not work with duo therm system. Anyone out there changed these out successfully?

15 Replies

  • Chris Bryant wrote:
    Old-Biscuit wrote:

    *G ------this is where you have to decide whether to install a 'mini switch' in thermostat cover so that you can wire BOTH fan speed controls
    OR just wire one.

    I only use HIGH speed therefore I only used the BLUE wire to 'G' terminal and taped off Orange wire

    IF you choose to install switch then you would wire Blue to one terminal on switch, Orange to other terminal on switch and then a jumper wire to 'G' terminal on t-stat


    You must hook up the orange wire for a DuoTherm- they use two relays, the orange turns the blower on, the blue toggles between high and low. If you just connect the blue, you get no fan.


    You must have been quoting/tying as I was correcting :B

    Memory lapse. Forgot when I wired mine the blue alone didn't work then had to wire orange/blue to get high fan
  • Old-Biscuit wrote:

    *G ------this is where you have to decide whether to install a 'mini switch' in thermostat cover so that you can wire BOTH fan speed controls
    OR just wire one.

    I only use HIGH speed therefore I only used the BLUE wire to 'G' terminal and taped off Orange wire

    IF you choose to install switch then you would wire Blue to one terminal on switch, Orange to other terminal on switch and then a jumper wire to 'G' terminal on t-stat


    You must hook up the orange wire for a DuoTherm- they use two relays, the orange turns the blower on, the blue toggles between high and low. If you just connect the blue, you get no fan.
  • Duotherm

    RED .......(NOT USED TAPE IT OFF)
    YELLOW ....A/C Compressor
    WHITE .....Furnace
    *ORANGE ,,,,A/C Fan Low
    *BLUE ,,,,,,A/C Fan High
    GREEN .....Ground

    Hunter

    RC/RH .....Green
    Y .........Yellow
    W .........White
    *G ........Orange/Blue



    *G ------this is where you have to decide whether to install a 'mini switch' in thermostat cover so that you can wire BOTH fan speed controls
    OR just wire one.

    I only use HIGH speed therefore I only used the BLUE wire to 'G' terminal and taped off Orange wire


    NOTE: May need to wire orange/blue together to get HIGH Speed.
    Memory lapse!



  • I have the Honeywell which did not have instructions that your model has
    Hunter Manual

    I'm not trying to be a Captain Obvious but have your marked the wires as outlined in the manual. I realize that not all trailers would be the same if the installer was not using this as a standard. How far did you get? If you have not removed the old one, take a photo of the old wire installation and follow the instructions.