| Maybe it is the control board?
I tested the "high limit" switch and the "vacum" switch, by #1 taking them out of the system and testing continunity, and then putting a voltmeter on the circuit and to ground, and watched it the circuit close (continuity) when the inducer blower starts and creates the updraft. SO, I am convinced it is not either of those two sensors.
On the "flame sensor" I took the one out of the idential system in the basement and put it in this sytem and no go. And the flame sensor from the 1st system works in the 2nd system, and I cleaned both with fine steel wook. SO, I am convinced that is is not the "flame sensor" itself.
HOWEVER, I am thinking that somehow even though the "flame sensor" itself works, but maybe the circuit does not. I did make sure all of the connectors on the control board were seated, but still no luck.
So again (detailed info in the original posting below), the 4 burnners light, but then about 3-4 seconds later the flame goes out. It tries again 4 times, then the system shuts off and stops trying.
Any other ideas?  |