Replacing Duo therm thermostat, need help.

[chiefward]

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?

[Sfla2]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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?

[Old-Biscuit]

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

[Chris_Bryant]

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.

[Old-Biscuit]

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!

[Tachdriver]

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.