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Adjustment of burner flame on Dunkirk boiler, what is correct?

I was finishing up my cleaning of my Dunkirk PWB-8d(Gas fired, atmospheric) and looking at the flame height/composition on the burners.

I was wondering what was ideal/recommended?  My flames were about 2 inches high, about 1/3 blue, about 2/3 yellow.  I did test moving the orifices a bit but that honestly didn't seem to make much of a change.

More curious than anything else what is the best practice or goal, much like in High School Chemistry class where we adjusted the bunsen burner to be a pure blue flame.



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  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Requires a combustion analyzer...

    The only correct way to adjust a burner, even something as simple as your atmospheric burner, is to use an analyzer.

    That said, doing what you did in high school is probably the best thing to do if you don't have an analyzer...


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  • Tim McElwain
    Tim McElwain Member Posts: 4,628
    I can't emphasize too much

    the need to do a combustion test to dial in the burner to its maximum efficiency.

    It is however a good idea to first clock the burner to make sure it is in the ball park as far as input. You then need to check the gas inlet and outlet pressure. Initially set the pressure to match the rating plate recommended setting. If the unit is under or over fired then a pressure or orifice adjustment is needed. Orifices on gas burners are not adjustable but must drilled to the correct size.

    The primary air shutter should be adjusted to get the gas burner to be a soft blue flame, no roaring, lifting or floating around. There should not be any yellow in the flame. Do not mistake orange as yellow, orange is caused by stirring up dust and rust and is not a problem.

    If much of this is new to you I sell a "Fundamentals of Gas" that explains it all and also has all the charts and table needed to set up a burner.

    Combustion testing and set up should be done by a professional who has had proper training. I can recommend Jim Davis or my classes for that training.
  • Al Roethlisberger
    Al Roethlisberger Member Posts: 194

    Thanks, it sounds like I need to find someone that can do the analysis, which is what I suspected.  I can do a lot, but this isn't an area of expertise for me.

    Moving the shutters doesn't seem to affect the flame much in my case, so something else in the adjustment is probably amiss.  It's been running this way for 15+ years(I am the first I'm sure to do *any* maintenance on it), so it can only get better :)



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