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?

Maybe this will helpHunter thermostat install

I have the Honeywell which did not have instructions that your model has Hunter ManualI'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.

Duotherm RED .......(NOT USED TAPE IT OFF)YELLOW ....A/C CompressorWHITE .....Furnace*ORANGE ,,,,A/C Fan Low *BLUE ,,,,,,A/C Fan HighGREEN .....GroundHunter RC/RH .....GreenY .........YellowW .........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 wireNOTE: May need to wire orange/blue together to get HIGH Speed.Memory lapse!

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 wireIF 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-statYou 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.

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 wireIF 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-statYou 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 :BMemory lapse. Forgot when I wired mine the blue alone didn't work then had to wire orange/blue to get high fan

Replacing Duo therm thermostat, need help. | Good Sam Community

15 Replies

Sfla2
Explorer
Feb 22, 2016
chiefward wrote:
Finally installed my Hunter thermostat this past week while camping with electric hookup and using Old Biscuit's instructions and everything works fine. Hoping the use of high speed fan only will stop the moisture buildup I have experienced on humid days in the past.
what i did was add reg rv switch just above stat to change speeds RVdesigner for switch
time2roll
Nomad
Feb 22, 2016
chiefward wrote:
If I can find a digital exact replacement, I would buy that, even if I have to pay triple the price of a Hunter. I just happen to have a Hunter laying in my stuff pile.
Did you look at a Dometic?

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26820366.cfm

Glad to hear the Hunter is working.
chiefward
Explorer
Feb 22, 2016
Finally installed my Hunter thermostat this past week while camping with electric hookup and using Old Biscuit's instructions and everything works fine. Hoping the use of high speed fan only will stop the moisture buildup I have experienced on humid days in the past.
Old-Biscuit
Explorer III
Oct 02, 2015
Old analog t-stat ----set point 68*F for heat. Furnace finally turns off at 72*F and then comes back on at 65*F.
Set point at 72*F for cool. A/C tuns off at 69*F and back on at 74*F

Hunter (Honeywell etc) Digital t-stat....furnace or A/C c turn on/off 1*F difference.

Inexpensive means of upgrading temp control in RV
chiefward
Explorer
Oct 02, 2015
Bob Shaw. My ac is working fine. The current duo therm thermostat is the original analog type. I hate it because i*m constantly having to adjusting the setting to keep the trailer comfortable. Plus the face lettering has faded to where you have to guess the settings. If I can find a digital exact replacement, I would buy that, even if I have to pay triple the price of a Hunter. I just happen to have a Hunter laying in my stuff pile.

My analog duo therm part number is 3107541.006. If you know of a replacement I would appreciate a heads up. My research hasn't been successful. Seems like most everyone replaces theirs with Hunter or Honeywell and modifies them to make them work.
Bob_Shaw
Explorer
Oct 02, 2015
Quick question, why do you want to replace your thermostat? Is it not working correctly? If not, are you sure it is the thermostat? Mine turned-out to be the controller, and I had to replace both the controller and the thermostat.
Old-Biscuit
Explorer III
Oct 02, 2015
chiefward wrote:
Old-bisquit. If I'm understanding your drawing concerning the fan speed control, the orange wire is connected directly to the G terminal which will give me low speed. Then to get hi speed I turn the added on-off switch to the on position to get high speed fan.

YES if you add a switch.........blue wire to switch then a wire to from switch to 'G' terminal.

OR

IF you just want High Speed Fan (what I only use cause low speed could ice up evap cooler in A/C Unit) wire the Orange & Blue directly to 'G' terminal.
Then you will have JUST High Speed Fan.
chiefward
Explorer
Oct 02, 2015
Old-bisquit. If I'm understanding your drawing concerning the fan speed control, the orange wire is connected directly to the G terminal which will give me low speed. Then to get hi speed I turn the added on-off switch to the on position to get high speed fan.
Sfla2
Explorer
Oct 02, 2015
chiefward wrote:
Thanks guys for quick response. I'm tired of thinking about it today. Will study y'alls input and deal with it later. One thing I noticed. My Hunter is model 42999 and the model referenced above is 42999b. Would that make a difference?

same
chiefward
Explorer
Oct 01, 2015
Thanks guys for quick response. I'm tired of thinking about it today. Will study y'alls input and deal with it later. One thing I noticed. My Hunter is model 42999 and the model referenced above is 42999b. Would that make a difference?