Flaky Furnace Thermostat

[gepaine]

I have a Suburban gas furnace in my 4-year old Crossroads Springfield. The thermostat name on the front panel is "RVComfort.HP". When heating on propane only (that is, not using the heat pump), the thermostat will randomly change the temp setting from our daytime setting of 69 or our night time setting of 66 degrees to 72 degrees. All by itself.

I believe that 72 degrees is the thermostat's default setting; i.e., when I first turn on the batteries, the thermostat sets itself to 72 degrees. I suspect that something is causing the thermostat to reset to it's default setting. It could be a momentary loss of 12-volts to it, but I doubt that is the reason because I can't think of anything that would interrupt the voltage from the batteries. (It happens when we dry camp or are hooked up to site power.)

I have replaced the thermostat with one of the same model, but the problem persists. I have checked the fuse connection at the 12 volt fuse panel and the connections behind the T-stat. On the iRV2 Forum, it was suggested that noise on the ground line caused by an LED could cause the problem, but there are no LED's on when it happens in the middle of the night.

Has anyone seen this before?

[Wingerdinger]

A quick Google search for this problem on that thermostat revealed that there is a problem with it picking up electrical noise. They speak of an 'isolation relay kit' that is installed to fix the problem. I found that on the Jayco forum.
I would contact the manufacturer of the thermostat, and see what they say. Perhaps they have a kit they can send you.
Also, usually the thermostat is wired fairly close to the head unit, and you can run a shielded, heavier wire from the thermostat to the head unit.
Otherwise, as a last resort, I would try another, different make/model thermostat.

[gepaine]

Originally Posted by Wingerdinger

A quick Google search for this problem on that thermostat revealed that there is a problem with it picking up electrical noise. They speak of an 'isolation relay kit' that is installed to fix the problem. I found that on the Jayco forum.
I would contact the manufacturer of the thermostat, and see what they say. Perhaps they have a kit they can send you.
Also, usually the thermostat is wired fairly close to the head unit, and you can run a shielded, heavier wire from the thermostat to the head unit.
Otherwise, as a last resort, I would try another, different make/model thermostat.

Thanks for the response. When I first heard of the "noise" problem reported on the iRV2 forum, I had hopes that I had found the cause. However, a response from an RV tech on the rv.net forum indicated that my thermostat did not have the noise problem, and that the symptom of the problem with the relevant thermostat was that the display would go to "00", not "72".

Also, I was never able to find a posting or web article that tied the noise problem to my model thermostat. If you have found such a connection, please post a link to it.

I have tried to contact the manufacturer, but they will only talk to "qualified repair technicians".

Again, thanks for the ideas.