15 years old
Went to start furnace for the first time of the season. It would not ignite and I tried several times. Controls, purge cycles,hot surface igniter, gas valve all seem to follow normal sequence. Inductor fan output great all limits test ok.
Robertshaw 7200 DER SO 3. I broke the pilot output of the valve and there is gas coming out at the appropriate time in the ignition cyle. But there was no flame. Assume the pilot which feeds the crossover was plugged at the oriface or elsewhere. So I opened up the burner compartment and discovered that 2 of the ribbon burners are partially corroded out - Couple of 1-2" gaps in each. The tube at the igniter is fine.
I have new burner on order but I'm second guessing that decision. Its about 2 weeks out and it is getting cold at night so I made a temp repair to the burner. Won't go into details but I have plugged the gaps in the ribbon and provided roughly equivalent opening to the ribbon.
Cleaned the rest of the burner and reinstalled. Still no ignition, well at least not all the time. It will go through the cycle and not light and then on the second or third try it will light. My repair burns perfectly with a nice even blue flame over the entire burner. I'm starting to worry that maybe it is not solely a burner issue and that I may have a gas valve issue. With the cost of the burner and a gas valve I'm into a reality check if I should just bite the bullet and replace the furnace. Its a lot of money right before Christmas. HO HO Humbug.
I neglected to clean the main orifaces during my rush to try out the fix. Any body ever experience these symptoms. Could burner open area and/or a partially restricted oriface cause the mis fire or is this more likely a gas valve issue??