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Author Topic: Furnace not kicking on automatically when temperature drops below setting.  (Read 422 times)


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Hi everyone! I've scoured across a decent amount of related posts here but none of them have been of any help to my specific issue. I've just recently moved into a 2002 jayco eagle 5th wheel. I've worked in the campground im staying at for about 5 years now but with all my experience i've yet to do anything furnace related. I just swapped out the old coleman mach thermostat that originally came in the unit for a Honeywell non programmable digital unit hoping it would solve my issue but it has not. Basically everything works as it should except for the furnace automatically turning back on when it falls below the set temperature. It shuts off when it reaches said temp just never relights. However if i manually shut off the heat and turn it back on the furnace fires right up. If my research is correct after the furnace shuts off the fan should continue to run for a few minutes and then shut down, which it does. The one odd thing I've found is if I manually set the temp lower than the rv to basically force the automatic shut off when I raise the thermostat temp with the fan still running instead of the heat kicking back on it actually shuts the fan down and wont do anything until I manually turn the heat off and back on again. I've scoured the internet and unfortunately came up dry which has led me here. Big preemptive thank you to anyone who can chime in with any tips or advice, its much appreciated!

Lou Schneider

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Welcome to The RV Forum!

What kind of furnace do you have?

All the thermostat does is send a heat request signal to the furnace, like an on-off switch.  The fact that it isn't restarting when the thermostat calls for heat points to a problem in the furnace's internal logic, not in the thermostat.  Shutting the power off and then on resets the logic and clears whatever was keeping the furnace off.

Again, it would help to know the make and model of your furnace.
« Last Edit: December 31, 2017, 12:48:48 AM by Lou Schneider »

Gary RV_Wizard

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Start by reviewing an article I wrote on RV Furnace Troubleshooting. It's in the forum Library at http://www.rvforum.net/miscfiles/Furnace_Trouble-2.pdf

As Lou says, all the thermostat does is signal "heat needed" as long as the Actual temp is below the Set temp. The furnace decides what to do about it and controls all the actions, both fan and burner. The furnace has its own electric power source and has its own logic (circuit) board to control the fan, the gas supply and ignition. Also the safety interlocks and run procedures.
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL