I have a Rheem Imperial 90+ furnace, that was installed in 1989. Model RGEB 07EC FS. Sometimes, when this furnace lights, 2 of the 3 burners do not light right away. They finally light when the circulation blower comes on. I have had 3 different service persons look at it, and it never seems to do it when they are here. Today it did, once, while the repairman was here. He could not find any problem that he could put his finger on, and he called in to his shop. They said they have run into this before, and were never able to resolve the problem.

Does anyone have any ideas???
I hate to replace the furnace if it can be repaired.