Furnace shuts down.

[msubobcats]

By the sig, we have a 2016 284RDBWE Cougar 5th Wheel.
We are getting ready to move and will slowly get the 5ver ready for the trip to Idaho. Plugged into shore power and turned on our furnace. It will run for a short bit but then shuts off. Worked great the last time we used it 3 or so months ago. Not sure how long it runs before shutting down.
At thermostat will turn on unit to auto and then set temp to 65, it starts then off (not sure how long because I leave and come back later and off).
Any ideas.
Thanks

[chuckster57]

Ok. First thing make sure there is propane in the tanks and they are turned on. Then go inside the trailer and light the stove burners. If they light with a good flame, then turn the stove off.
Now, turn the thermostat to heat and turn it up all the way. As soon as you can, go outside to the furnace and listen close. You should hear the fan running and about 30 seconds later you should hear "clicking" as the igniter tries to light the flame. If that doesn't happen then there are a few possibilities.

Here is the order of operation:
1) thermostat is set to furnace and temp set to command heat
2) control board sends current to the "limit" switch ( limit switch will stop flow of LP if the temp in heater is too high.
3) assuming limit switch is good and the temp inside heater is okay, current is then sent to the "sail" switch. (Sail switch is a switch in the fan housing with a long "tail" that catches the wind and completes a circuit.
4) assuming the fan is spinning fast enough to make the sail switch complete the circuit, the current then returns to the control board
5) control board commands the gas valve to open and the igniter to start sparking.
6) if the flame ignites, the igniter becomes a flame sensor and the gas valve stays open..coach warms to set temp and flame shuts off, furnace goes into cool down cycle.

If any of the above doesn't occur, then you have to find out which step didn't happen.

Let me know what happens when you turn the heat up and stand by the furnace outside. If you smell propane and no spark, then we may have a different problem (mud dawbers/paper wasps).

[msubobcats]

Am I wrong? I though it was electric. Did I just learn something?

[chuckster57]

Furnace uses 12V to operate fan, control board and igniter. LP is burned to create the heat. You might be thinking water heater, it operates on either LP or 110VAC ( or both).

[msubobcats]

Thanks.
I had really never noticed. Even though the propane was always on when we were out it just never dawned on me.

HAND PALM TO FOREHEAD

[chuckster57]

So is the furnace working?

[msubobcats]

I will check it in the morning...

[msubobcats]

I feel like a goober but will not be the first time. When I operate the equipment correctly it works.
Thank you.

[chuckster57]

Your very welcome. No need to feel like a goober, truth be told we all have our moments. Just glad you got it going without any expense :applause:

[Sprout2mo]

If propane has run out....will the furnace shutoff right away? My old 2000 Fleetwood Tioga RV used to blow and blow cold air until I realized it was cold and propane gone to turn it off manually. Almost froze a couple of times! I think my 2018 Cougar shuts off right away when propane runs out. I’d just like confirmation, please. I’m currently in this position where propane is low and it’s bitter cold for another day and hopefully my propane doesn’t run out, but if it does, I hope it shuts off and doesn’t blow cold air until I manually turn it off.

[ChuckS]

What would occur when you run out of propane is...
... furnace will attempt to relight 3 times
... after 3 failures to ignite control module will then go into lock out mode
... should stay in LO mode until either. Thermostat is turned off or DC power to furnace is killed.

[Sprout2mo]

Would the blower/fan stop or continue to run until manually switching furnace off?

[ChuckS]

If the lockout is working correctly on the furnace control module after it failed 3 light off attempts the fan will stop ...

Nothing should happen again until either you turn thermostat off and back on ... clearing lockout mode OR you kill DC power to RV