Thanks to you both for your responses.
The sail switch appears to be functioning properly -- I checked it with an ohmmeter. If the switch was stuck in the open position, it is my understanding that the fan wouldn't turn on. If it was stuck closed, the gas valve wouldn't open. And we don't experience either of those conditions.
As to whether the spark is in the path of the gas: the spark electrode (which was replaced) comes preformed. The new one looks just like the original one. It sits approximately 1/2" above the burner opening. There is no way to move it unless I bend the electrodes. You can't install it backwards because the high voltage wire would not reach the electrode tab. You can't move it too much closer because the spark gap would not be in the proper location with respect to the flame to keep the gas valve open when the heater is on.
Are we missing something?
Thanks! It's getting cold out here (we're currently in the northeast)!
Dave
