Furnace misbehaving.

[kellem]

Was shoveling snow around the trailer today " 2020 Outback " and heard the furnace cycle without ignition.
Ran inside and turned thermostat up and same result.

Ran the stove burners for couple minutes and tried again, furnace fired right up and worked flawlessly the rest of the afternoon.

I understand air in the system could cause this but this tank has been hooked up for a week, furnace running and 3/4 full.

I'm mechanically inclined but weak with HVAC.

[time2roll]

kellem wrote:
It ended up pulling the furnace and replacing sail switch....problem solved.

Wow that seems like an early failure.

[kellem]

It ended up pulling the furnace and replacing sail switch....problem solved.

[CavemanCharlie]

Old-Biscuit wrote:
"I understand air in the system could cause this but this tank has been hooked up for a week, furnace running and 3/4 full."

Air is NOT in system ---you have propane valved in/furnace running for a week.

Then you fired off stove top burners which lit off and then furnace fired up

LP Reg was in Lockup.
When furnace turned off the LP System Pressure went high due to no demand.
LP Reg goes into Lockup to prevent excessively high system pressure (above 14"WC)
Then when furnace tried to fire off....system needed longer duration of demand to establish flow and LP Reg to start controlling
Stove top burners provided that demand w/o shutting off like the furnace does when no Flame Proving signal is generated

So what can be done to keep it from happening every now and then when the furnace shuts off ?? It would kinda suck if you have to keep waking up at night to start the stove just to get the regulator to work.

[Old-Biscuit]

"I understand air in the system could cause this but this tank has been hooked up for a week, furnace running and 3/4 full."

Air is NOT in system ---you have propane valved in/furnace running for a week.

Then you fired off stove top burners which lit off and then furnace fired up

LP Reg was in Lockup.
When furnace turned off the LP System Pressure went high due to no demand.
LP Reg goes into Lockup to prevent excessively high system pressure (above 14"WC)
Then when furnace tried to fire off....system needed longer duration of demand to establish flow and LP Reg to start controlling
Stove top burners provided that demand w/o shutting off like the furnace does when no Flame Proving signal is generated

[wa8yxm]

Air in the lines is a common Suggestion and not all that likely.

However there are failure modes where it may take a few tries to fire up.

I pulled several hairs out diagnosing mine. Turned out to be a bad control board (NOT suggesting that's your problems) there is an entire list of things to check.

Twice (and that was one. My parent's house furnace the other) When I checked the ignightor spark gap I was amazed It was like 4 times what it was supposed to be (READ THE MANUAL PLEASE) I reset and problems vanished. Twice.. Alas on the RV they returned and yes I know why (Bad design the wide gap damaged the board) If you do need a new board.. Dinosaur boards made my replacement. As a trained electronics type I was impressed with their board. Very well built.

[PartyOf_Five]

On a home furnace there's a solenoid that gets corrosion on it, and eventually prevents the spark. Initially this is intermittent and then it becomes regular, ie regularly stops igniting. Hope that helps.