Here is the situation. Went on a call yesterday. Homeowner complained when the furnace came on it exploded real loud. He is absolutely right. On a call for heat. valve opens up, you can hear gas flow, but wont light. After a very length of time, it ignites and blows fire out the front sometimes two feet. which knocks out the pilot. Changed the valve, pulled the orfices and burners and wire brushed them and blew them out with air. Pilot is good and strong.
My question, do the burners have to place back in a sequence. I didnt think so cause i have cleaned several and never put them back in any certain way. NOte, that this furnace has been leaking water for quite a while cause the a coil drain line was clogged. water in the base of the furnace in the blower compartment. The burner chambers have evidence of heavy rust. Thought maybe heat exchanger rusted through but didnt think that would cause it not to light. Never run into this problem. Maybe some of you with more experience have and can give some advice on what the problem might be. Incidnetly, a couple of times it did light, one time only one burner lite and the other time three out of four lite.