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Gas fired boiler, oil in burner tubes

PMNightmare Member Posts: 1
I'm working on a fairly old (2014ish) Buderus boiler doing preventative maintenance. I'm also fairly new to working on gas boilers as I've only had experience with steam boilers.

There are three large burner tubes that feed in to the combustion chamber that mysteriously started leaking some kind of green oil a couple days after cleaning them (no water or chemicals used in burner tubes, water used to flush tank). Nobody seems to know what the oil could be or where it's coming from. The oil has since stopped, but we are still trying to determine what it is and where it came from.

Anyone experience this before that could possibly clue me in on what it is? 


  • ChrisJ
    ChrisJ Member Posts: 14,414
    Did you pull the cap off of the drip leg to see if it's clean and dry?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ratio
    ratio Member Posts: 3,404
    Glycol, maybe?
  • Lance
    Lance Member Posts: 243
    Gas fired, Huh? Oil you say? Could be threading oil finally made its way out. If it was thread oil it is unusual to see it there. Usually that gets trapped in drip legs. If it was the threader, he probably sloped his pipe the wrong way while cutting. I have seen 3/4" * 7" drip legs full of oil before.
  • mattmia2
    mattmia2 Member Posts: 7,733
    Maybe it is from the outside utility. Could be worth taking off the drip leg and looking inside.
    JUGHNE Member Posts: 10,568
    Did it show up after re-firing the boiler?

    If it came out of the gas offices (assuming this is an atmospheric burner), then it must have passed thru the gas valve.
    It seems that any oil passing thru a gas valve could affect the 100% shut off ability of the valve, just like water.

    IIWM, I would remove the gas valve, manifold and orifices to check for the oil gooey.