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issues with my furance (weak flame and burners not always lighting)

1538 Views 11 Replies 5 Participants Last post by  beenthere
my luxaire furnace is 12 years old. i recently purchased the house with it.

furnace kicks on, ignitor glows but burners do not light. after doing some reading last night online i read that that gas valve might be sticking it tap on it when it tries to light the burners. worked about 1/2 the time. but flames look weak. is the valve not opening up all the way? once blower kicks on it seems that it sucks the weak flame so the burners go out. and then it goes though its relight cycle.

would my issue just be the gas valve? or is there other problems?
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If there is any difference in the flame when the blower kicks on there is a cracked heat exchanger. You will have to check in/out gas pressure of valve first to diagnose valve. But if heat xchanger compromised it doesn't matter what the gas valve does.
burner flames die when blower kicks on
Small chance of an electrical issue, I would check voltage at gas valve to see if it drops considerably when blower kicks in. A small drop of few tenths of a volt can be expected.
Right, because tearing into burner assembly is way simpler than checking voltage.
Right, because tearing into burner assembly is way simpler than checking voltage.
The intent of the comment was to look for simple things like power as you suggested of dirty burners as I suggested and not go right into replacing expensive parts that may not need them. Since you obviously know more about this than I do I will remove my previous suggestion as it is obviously not a sound one.
It may come to a point where doing what you suggested is necessary . However, some burner assemblies are very tricky and involve removing lots of parts. The easiest thing to do would be check manifold pressure, if it's correct then get into cleaning burners, etc. I had a single shot burner orifice a spider decided to call home gas pressure good, temp rise very poor
went home on lunch and checked it out. furnace is working fine now. didnt do anything to it. flame is back to normal and gas valve is opening and closing at it should.

could a sticking valve cause the weak flame i had earlier? could it partial open? just wondering if i just have the valve going bad or if there could be another issue.
Very well could be, depending on gv it could open in different ways, or not depending on your perspective.
Can't tell without checking pressures as already stated. For all we know the problem could be a sticking regulator on the gas meter outside.
Or the gas company had the line shut off or was running low on gas pressure due to maintenance work somewhere.
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