Duo-Therm Comfort Control Thermostat

February 06, 2022, 12:22:22 pm

We recently replaced the front (zone 1) Duo-therm heat pump with a 15k Atwood unit. Naturally the Atwood unit needed it's own separate thermostat which I installed and unit seems to work correctly. The problem is that with no zone 1 unit connected to the comfort control thermostat the zone 2 unit does not recognize the rear furnace. There are two furnaces one for each zone.
What do I need to do to fix this problem. Luckily we live and travel mostly in the warmer southeast. The heat pumps will normally keep the coach comfortable. But if you have furnaces they should work.

Nick

Re: Duo-Therm Comfort Control Thermostat

Reply #1 – February 06, 2022, 11:33:28 pm

Hi Nick,

It sounds as though your Dometic comfort control thermostat was first connected to the air conditioner you have now replaced. The easiest solution could be to leave the old thermostat where it is and connect the thermostat cable directly to daisy-chain cable in the ceiling that goes to the remaining Dometic air conditioner. Depending upon your situation, you may need a pass-thru coupler or a reversing-coupler to do this. See if a coupler was left over during the change-out.

FYI should you decide to replace a cable or move the old thermostat, Dometic uses 4 conductor "data" cables, not regular telephone cables (unless a "reversing" or possibly "straight" coupler was used).

Note that the RG11 plugs have slots for 6 insulated wires, but only 4 are used. If you need to find a straight-thru or reversing coupler or data cables; try Lowes, Home Depot, Amazon or eBay, etc. Oddly Walmart calls their data cables "straight phone" cables. It is possible to convert a phone cable to a data cable.

Lastly you might need to do the "reset procedure" on the old thermostat to find your remaining A/C and furnace. Try everything first though. For just one air conditioner the reset results in no zone number showing on the display.

Good Luck,

Jim Frerichs
2002 U320

3 zero eight - 4 4 zero - 5 one five 4

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