In message , Bob Smith
writes


The mother board is probably the more expensive and the more likely.
The flame detection probably has some time delay built in - i.e. 10
seconds with no flame goes to lockout.
Ergo the problem is more likely the main board.


It's not the main board. I replaced it today, and all the strange symptoms
are still there.

Could it be the solenoid on the gas valve, or the ignition board?

Did I not mention earlier to measure the resistance of the solenoid ?

You're asking questions that people can only guess at without you
providing more information


--
geoff