Furnace works; then doesn't; works again?

[VA-Apraisr]

2003 Fourwinds E450. Last trip to NY, furnace did fine all day but went to bed and wouldn't hold temperature and could hear blow turn on but ignitor won't fire, so turned it off. Just got it back from RV repair and they said they replaced the circuit board. Checked it before I left and turned on, but as soon as I get home, won't turn on. Kept running thermostat up and down but nothing. Using a digital Honeywell thermostat btw and it's almost new. Can hear the "click" each time I turn off/on so think that's ok. So, turned it off and back on and it fired up again. Got up to 70 degrees, it turned off, and won't come back on to keep temp at 70. I've tried it hooked to house power, batteries and generator....makes no difference. House batteries are at 12.9amp so shouldn't be an issue. Before I lug it back 40 miles to shop, any ideas from the "thinking men" on the board?

[bobndot]

VA-Apraisr wrote:
UPDATE: Furnace worked all week just fine! I did inspect the ducts underneath cabinetry and appears they were shortened to fit more snug and without any kinks. So, most likely the thermostat (and will replace promptly if this ever happens again!) before going to RV mechanic.

"most likely the thermostat" yes, I agree with you, just stick with what you have now...it works .
Sometimes home type digital thermostats can be used and sometimes not.

Well, look at the positive side of all this, think of how much lighter your rv is now that you have shortened your ductwork :B

Glad it all worked out and you had a good time in N.C.
be well,
Bob

[Texkoch]

My Atwood burner was grounding out the the electrode /spark igniter to the burner. Wish I could copy and pate an image. I took the old burner off and installed a new burner. Two wires and 4 -1/4” nuts. I started to get a sail switch but it works fine. Good luck.

[VA-Apraisr]

UPDATE: Furnace worked all week just fine! I did inspect the ducts underneath cabinetry and appears they were shortened to fit more snug and without any kinks. So, most likely the thermostat (and will replace promptly if this ever happens again!) before going to RV mechanic.

[Texkoch]

My Atwood burner was grounding out the the electrode /spark igniter to the burner. Wish I could copy and pate an image. I took the old burner off and installed a new burner. Two wires and 4 -1/4” nuts. I started to get a sail switch but it works fine. Good luck.

[Bordercollie]

The furnace in our 2004 Tioga has always worked without problems, but it is comforting when it comes on and cycles properly. There are a lot of DIY videos on You Tube on trouble shooting and fixing furnaces, etc. Finding a good RV furnace repair guy may be difficult.

[VA-Apraisr]

Guessing ducts were only slightly kinked since I've never inspected or moved any of them (thinking RV tech was just covering up for the fact that the thermostat was the ONLY issue and they had already installed a new board).

[ron_dittmer]

It sounds like you are in good order again. I find it strange that your ducts were kinked. Were they kinked since the rig was new? Or are they in places where your stuff has kinked them.

It seems that your digital thermostat might have been the real culprit. We have the mechanical one shown and love it. I would never get a digital one for the way we use our rig.


At home, we had a digital thermostat for many years and we both cursed it. I finally had a Popeye moment "It's all I can stands, and I can't stands no more". We are back to the old round Honeywell with the coil spring and mercury switch inside.

[VA-Apraisr]

Man o man....you guys are a valuable knowledge pool of thoughts!! Yes, I feel it was mainly the Lowe's brand Honeywell not syncing with the RV. But, I've now got a new circuit board, unkinked ducts and new thermostat. Sadly, throw enough money at it and sooner or later a dart will hit the target 🙂 I had better be WARM on that BEACH.

[Old-Biscuit]

Sounds like it was the 'thermostat'......

The 'kinked up' ductwork COULD cause issues with air flow (not enough thru the heat exchanger) which would cause overheating and the High Temp Limit Switch would open shutting down gas valve
BUT fan would continue to run....High Temp Limit only stops DC circuit to circuit board NOT DC to Fan.
Fan continues to run cooling down heat exchanger/High Temp Limit Switch Closes ...DC back on circuit board which opens gas vlave/spark electrode fires and re lights because Thermostat Temp Set Point has NOT been reached.

Furnace firing off....reaching t-stat set point and then NOT refiring when temp drops is usually an issue with the thermostat

[bobndot]

Thank you for the update, it might have been a combination of the thermostat and that kinked hose. Either way, its good news to hear that it cycled enough times to keep it warm.
Enjoy, N.C.
Bob

[VA-Apraisr]

UPDATE: so, they had already replaced the main board (maybe unnecessary?) and nothing had changed. So, this time, the removed the Honeywell digital thermostat and replaced with White-Rogers analog RV thermostat and also straightened out the heating duct beneath the sink/couch/bedroom areas since they said they were "kinked up" in several places and thought that was causing a high heat sensor to trip the furnace off and not auto-start back up. They said they left furnace on last night with temps here going down into the high 30's and said camper was toasty warm this morning. Seems to be working as I type but will know for sure once I'm on the cool beaches of North Carolina this weekend and next week.

[VA-Apraisr]

Yes, tried the range running to make sure gas was available, turned off tank and back on, turned water heater on, ..... it's back at shop and will post results (positive I hope) once they figure it out. Told them to check digital thermostat and maybe try a manual thermostat; also check regulator to ensure proper propane pressure, and pull heater box apart and look for any rust. Fingers crossed XX

[ron_dittmer]

Bordercollie wrote:
Furnaces have a lot of safety devices that need to work properly with a steady flow of propane.

Excellent point!

Run your stove for a few minutes to evacuate air in the line, especially after service was just completed on any propane appliance.

[Bordercollie]

I once found a loose screw connection at the fuse panel that caused intermittent furnace action. Look also for loose or corroded ground or +12volt connections at the thermostat and at the furnace itself.

I had an old rig with an old furnace that was intermittent. I had to run the stove to clear air bubbles from propane lines. Furnaces have a lot of safety devices that need to work properly with a steady flow of propane.