RV Comfort Thermostat problem with gas furnace

[jfann]

I have an RV Comfort.ZC thermostat in a 2007 fleetwood motorhome.  The thermostat has a zone 1 & 2 that controls 2-AC/heat pumps and 2-gas furnaces.  All works well except the gas furnace in zone 1.  The gas furnace fires and runs properly on the first cycle when the thermostat is first switched from off to heat, but on the second run cycle the gas furnace only runs for approximately 15 seconds and then stops.  I can make it run again by switching the thermostat setting to off and then back to heat.  Additionally, the temperature indicator on the thermostat never drops below the low temp number for the operating range when the gas furnace doesn't run.

Example:  If the thermostat is set to gas heat at 67 degrees, the furnace will start when the inside temp drops to 66 degrees and turn off when the temp rises to 68.  This happens on the first cycle as it should.  When the inside temp again drops to 66, the gas furnace will fire as it should, but will only run for 15 seconds or so, and then shut off.  The temp indicator on the thermostat will then remain at 66 degrees even when then temp inside the RV continues to fall into the lower 60's.  I can make the furnace run again by switching the mode from heat to off to heat.  The entire cycle with the problem will then repeat.

The Fleetwood tech hotline said this could be caused by RF interference from florescent lights and could be remedied with the installation of an RF blocking filter.  I tried running the unit without the lights on and still had the problem.  I do have a filter, but I am not sure where or how to install it.  Any and all help would be appreciated.

 

[Dukenrock]

I had some flakey issues with my exact thermostat.  I just replaced the entire T Stat this weekend with a new one because the mode switch broke. (2 zones same as yours in a 2002 American Eagle)

Try this:

Turn off both zones and remove the fuse from behind the cover.  Make sure no cell phones are plugged in or any charging devices. (It sounds crazy but there is RF interference)  After 5 minutes plug the fuse back in and see if it works properly.  If it does and the problem persists over time, you'll need the choke installed (RF filter)  To install the choke , you remove the T Stat, unplug it from behind the wall, and plug the choke in line.  Simple install and it appeared to take care of my problems.

Hopefully just pulling the fuse out for 5 minutes will do the trick...

 

[jfann]

Thanks... I pulled the fuse for about 5 minutes and it temporarily fixed the problem.  The furnace ran three or four times and then locked up again.  I purchased a clip on choke filter from Radio Shack and will try to install it tomorrow.  I'm not really sure which wire to install it on, but I am guessing the power feed to the thermostat would be the best location.  I'll let you know how it does after the filter is installed.  I appreciate your help.

 

[Dukenrock]

There is a choke that you can purchase directly from the T Stat manufacturer for about 30 bucks.  It has the factory plugs that will allow you to unplug your T Stat and plug directly in line.  Mine acted up a lot before I did that.  Even after that, once in a while it would act flakey.  I'm hoping that the new T Stat will be trouble free!

Check and see if your lights around the T Stat are florescent.  If so, shut them off, try the  fuse again and see if it makes a difference.

Here is a Tech support line that I had filed away. (I think this is the one I called)  (316)832-4357