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Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 21546
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I have a Dunkirk PSB-4D steam boiler. The burner burn with a

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I have a Dunkirk PSB-4D steam boiler. The burner burn with a 4in yellow flame and lots of soot. I have cleaned between the boiler section and resealed the draft diverter . None of this seems to affect the flame. I would appreciate any help you to solve the problem.
James French

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

This could be caused by excessive gas manifold pressure (you need a gauge that reads in inches WC to set it properly) or inadequte air for combustion. If there are shutters on the burners opening the shutters could also help.

Customer: replied 7 months ago.
I cleaned out the burners with compressed air. The flame is now blue. How ever, the flame is very high and noisy.
The furnace is 9 years old. Is it time to replace the gas valve ?
J. French

Gas valves usually last longer than 9 years. I'd suggest you buy a pressure gauge that can read in inches WC and check the manifold pressure. It should be 3" to 3.5 ". If it's higher than that you may be able to adjust the valve to lower the pressure. If not then replace the valve

Customer: replied 7 months ago.
My burner problem was solved by replacing the gas valve.
J. French

Ok, I'd appreciate a favorable rating.

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