Seasons greetings,

My church recently received a used furnace when the t stat calls for heat the ignitor starts to glow after about 30-40 sec. the furnace lights and then after a few seconds the burners go out we recently changed the ignition module which is a white rodgers 50e47-843 after this was done the same process repeated again so we were told to clean the flame sensor which was done (same problem) then we replaced the flame sensor, and we still have the same problem what could it be please help:eek:

Check the polarity of the furnace your hot wire and neutral might be switched

Also make sure the furnace is properly grounded.

First of all, I'm no expert -- just happened to experience the same problem. My Concord 80 furnace would cycle 2-3 times with no problem, then flames would ignite but wouldn't stay lit. Out of pure curiosity, I vented the furnace cover about 2" to allow better airflow and IT WORKED! My furnace has been working perfectly ever since. Not sure if this "venting" will cause other problems, but for now I'm warm. I would appreciate any feedback from HVAC experts on this issue.