I've searched the groups for heating issues with the Criterion II and
only found people having issues AFTER the heat came on. I'm having an
issue with the unit before the heat comes on. The pre-purge runs for
30 seconds, I hear a single click sound, then several seconds later the
fan turns on with the gas. Not being an hvac person, it seemed like
the click was reminiscent of a bbq with an electric ignitor but it
didn't make sense with the gas coming on several seconds later...
After what I could gather on here, I still have a few questions. My
first question is: What is the name of the long, round single wire that
is bent 90 degrees and comes up in front of the gas? And, what is the
name of the part that also sits in front of the gas and is shaped like
an M made from square shaped metal?
I'm guessing that the M shaped sensor is the flame sensor and that
the single wire is the ignitor, correct? How would a properly running
ignitor function? Is it supposed to click a spark like a bbq or is it
supposed to get red hot? Any help I could get on this would be greatly
appreciated.

Pardon the inexperience, we all have to start somewhere and I don't
have a manual!
Tony