Quote:
Originally Posted by bucksnducks
Hey jasin1
Thanks for the suggestions. How do you cycle the power to the furnace? I can also try to purge the gas line again.
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Most modern furnaces have a circuit board that will lock itself out after so many consecutive attempts at lighting. It can then have the blower run continuously until the board is reset or cycled. Some times it means shutting off the breaker to the furnace( deenergizing the board) other boards may just need to be cycled off at the thermostat ( Heat ,Off ,back to heat). The reason I said to bleed the lines going to the FURNACE is because it may have had air trapped in the line initially after you ran out of gas and changed the tank. If it attempted to start and could not do so after 3 or possibly more or less attempts ,then it could go into lockout.The fan can come on because some of the boards are set up for worst case scenario for lockout...(Overheating.) Now I don’t claim to be an expert on Rv furnaces but I am on residential furnaces. When it initially tries to start it probably ..1)sparks to ignite pilot 2) proves pilot by flame sensor 3.) lights main burner.
The pilot orifice is very small and sometimes will not bleed out air fast enough for furnace to operate as designed unless you bleed the line..or keep trying to start it and reset board if lockout occurs
I tried to listen to what actually happened as in ...the gas ran out...changed tank...furnace would not light and blower runs continuously..
The igniter would not keep trying to light in lockout but fan probably would.
And yes it could be the infamous sail switch that everyone talks about. They seem to be problematic.That is one thing that is not commonly found on residential furnaces except older air cleaner setups but looking at the facts and the sequence of breakdown...I would say I’m leaning towards lockout.
The stove would bleed very easily because you are opening the burners and letting a lot of gas out at once. Propane is heavier then air so the furnace line could still have air trapped between the new gas in the line and the pilot orifice.