Duo Therm Comfort Control Thermostat

[truk4u]

I have the Comfort Control Thermostat that controls 3 roof A/C's. There is a big difference in the set temperature and the actual room temperature for each zone.

Does anyone know if there is a way to adjust the temperature spread in order to have the room temps closer to the set temps? No info in the manual.

8362
Thermostat

8363
Room Temp Sensor

[truk4u]

Let's try again!

[wayne cowart]

are you changing your thermostat to the other zones and adjusting the temp for each zone?

[AmeriStar]

I had to 'play' with the controller several days to really understand what it does. The primary problem you might consider is that all 3 zones are in a very small space and they overflow into each other. Where I had the best result, is in the bedroom with the door closed.
We really don't like the noise of the fan running all the time, So during the time when we sleep, we run 1 or 2 of the front units and use a fan to push the cool air to the back.

[truk4u]

Wayne - We keep 1 & 2 (galley & front) the same and the Bedroom a little cooler.

[JIM KELLER]

I have heard the sensors are prone to failure. Don't know how hard they are to replace.

[dmatz]

I placed a cotton ball under the sensor cap between the cap and sensor, it helped, seemed the sensor was reacting to fast to room temp.

[SteveCooper]

I placed a cotton ball under the sensor cap between the cap and sensor, it helped, seemed the sensor was reacting to fast to room temp.

What a great idea! I'm doing this tomorrow in the bedroom sensor. Thanks for the tip.

[Abaco]

I have the same controller for 3 roof A/C's. Does anyone know if it's possible to put a home type unit there that has more programming options or are we stuck with the factory unit ? It would require a controller that accepts the 3 zones. I don't know if putting 3 separate home style units would work but I don't hate it bad enough to do that. The little slide switch on the bottom is loose and just started shorting out so either need to remove it and repair or replace the unit. You would think the manufacture would help us out with an upgraded unit. Would also love to be able to control wire less from a slave unit in the back but unlikely I suppose.

Also, the filters from Royal seem to be inadequate. What about upgrading to a different filter instead of the super thin mesh they came with. I get dirt deposits on the white ceiling because the filters aren't doing their job. Can't a house type filter go there instead ? And the thermostat sensors. Sad. No retrofit or replacement suggestions ?

Thank you.

[BenC]

I have the same controller for 3 roof A/C's. Does anyone know if it's possible to put a home type unit there that has more programming options or are we stuck with the factory unit ? It would require a controller that accepts the 3 zones. I don't know if putting 3 separate home style units would work but I don't hate it bad enough to do that. The little slide switch on the bottom is loose and just started shorting out so either need to remove it and repair or replace the unit. You would think the manufacture would help us out with an upgraded unit. Would also love to be able to control wire less from a slave unit in the back but unlikely I suppose.
Thank you.

The Comfort Control Center system, or CCC as Dometic refers to it, was a great thought, but there were many installation errors that occured for the sake of "interior design" and looks that overroad and can cause erratic temperature readings. There is a chart in the Dometic technical training for the thermister resistance values, but you must access the white plug in the return air plenum, and should have a digital multimeter and IR temp sensor to verify if these values are correct, or if the thermister has failed. Most generally, I have seen that it is not a failure of the thermister, but installation error that results from inaccurate temp of the room, resulting in the AC either freezing you or shutting off prematurely.

Common problems:
1) Remote thermister bulb installed incorrectly under the cap, in contact with the cabinetry underneath, giving false readings.
2) Remote thermister being mounted too close to a window, or back underneath a cabinet, so that accurate room temperature is not "sensed" by it.
3) Lack of insulation behind the thermister bulb/cover, resulting in outside temperatures effecting the reading it gives to the AC.
4) Remote thermister or Comfort Control unit (if no remote thermister is connected to the white plug in the return air plenum, the AC unit "reads" the thermister built into the CCC unit itself) being mounted too close to an AC outlet duct, allowing for cold air from the AC discharge to blow on the thermister and cause it to shut off prematurely.
5) Remote thermister mounted in the return air plenum itself! This would work, and operate just like the Cruisair Units (most converters using Cruisair split systems put the indoor temp sensor in front of the return air screen at the evaporator), except that a Cruisair never completely shuts off the indoor blower, just ramps it down to minimum speed when the temperature is satisfied. In order for a Dometic roof AC to function properly with the thermister in the return air plenum, the fan would have to be locked on low or high, NOT auto. In auto, when the compressor shuts off, so does the fan and then there is no air flow, the return air plenum is NOT the same as the room temperature, and the unit will not come back on at a reasonable/accurate temperature.

We built 2 coaches for whom the customer did not like the Dometic CCC itself. The board in the upstairs unit had to be removed, and replaced with relays and a remote anti-freeze thermostat, and a transformer was installed to provide the 24volts AC on which conventional household thermostats operate. Each rooftop unit required its own separate thermostat mounted in each "zone". It was an invasive installation, and I would not recommend it as a normal practice, as few would want to replace the unit in the future if it failed due to the numerous modifications that are done to the unit. Also, the standard wiring between the CCC and each rooftop unit is just a 4-wire telephone-style cord, not enough wires to accomplish control via a conventional digital wall thermostat.