hi -i have an older american standard(over 30 years) and about 2 weeks ago the pilot started going out.after replacing the thermal coupling and my plumber doing different things it was decided i needed a new gas valve.however,
before i did this (and after lighting 20 times a day) i discovered that if the little access door to light the pilot was left off the pilot never went and as soon as i put the door back on the pilot would blow out after the heating cycle.i am
now looking at new furnaces because i don't want to go on and on.the "new" furnace estimator said his guess would be a slight crack in the heat exchanger--any ideas --thanks daryl
Good possibility a crack is the issue. Does the pilot blow out if you turn the fan on? At 30+ years of age it's almost always a good idea to cut you losses and start over. The fuel saving alone will pay for the furnace many times over.