York Gas Furnace

Does anyone know about hi eff gas furnaces? I am working on a York residential 95%, upflow, forced warm air. The problem is that sometimes not all of the four burners will light. Most of the time it lights fine and then continues to run properly and does not trip on the flame sensor circuit. When it does light the flame pressure and flame looks as it should. The first two burners will light and the last two, of course are where the flame sensor is located, do not light causing it to trip.
any ideas?

Hi NSWC
I am not familiar with your particular unit but I would think the principles of high efficiency furncaces we have here in oz would be the same.
Does this unit have in shot burners?
What does it use to allow the flame to propagate from one burner to the next?
Most units have a thin zip burner which connects one burner to the burner next to it. These will need to be perfectly clean to allow correct flame propagation.
Is the combustion chamber under vacuum or pressure when running. Do you have any air leakage resulting in turbulance.
Are ignition gas pressures measured at the manifold what you would expect on start up.
Hope this helps.

Thank you!
I pulled the gas burners and sure enough between the 2nd and 3rd burner the flame spreader opening was clogged. Cleaned the spreader areas and it is lighting fine now. One more question, I noticed that the # 3 burner lights right at the orifice occasionally. Any suggestions?

NSWC

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Originally Posted by NSWC

Thank you!
I pulled the gas burners and sure enough between the 2nd and 3rd burner the flame spreader opening was clogged. Cleaned the spreader areas and it is lighting fine now. One more question, I noticed that the # 3 burner lights right at the orifice occasionally. Any suggestions?

NSWC

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Good to hear your on the right track.
Again i am not familliar with the unit you have. I am guessing that by the by no.3 issue it is lighting on the injector. Maybe low gas pressure at the orifice/injector or again turbulance. This sounds like an induced draught system, if the combustion fan was an issue it would be common to all burners so you could rule that out. Other than that i cant offer more advice as i have not seen one do this before.