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Unburned Oil on Nozzle

Richtdow Member Posts: 22
On startup I‘m getting a light growl when the burner lights. I removed the burner and checked all of the measurements of the electrodes and Z distance. Everything was fine with those but I noticed a light coating of fuel oil on the nozzle. Does this have anything to do with my growl sound and, if so, what can I do to fix it? I‘ve done an efficiency test with smoke and got a reading of 1.

Burner: Beckett AFG with Genisys


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,132
    What are you firing into? Make /model? What type of venting-chimney, power vent, etc.
    First you run the burner to steady state. Then you adjust draft.
    Then you do your smoke test.
    If you did it properly, you need more air, to get it to true zero smoke, then put your analyzer in there for the rest of your numbers and final adjustments.
    Unburnt oil on the nozzle can be from any or a combination of:
    • 1. Clogged/partially clogged heat exchanger.
    • 2. Poor draft/positive overfire draft.
    • 3. Partially blocked nozzle.
    • 4. Poor cutoff from fuel pump.
    • 5. Air in nozzle line.
    • 6. Lack of post purge
    • And on and on...
    EBEBRATT-Ed Member Posts: 13,442
    usually oil on the outside of the nozzle is a result of back pressure around the burner tube but the cause could be a multitude of things as @STEVEusaPA pointed out
  • Richtdow
    Richtdow Member Posts: 22
    Thank you. I have a Weil Mclain WGO-2 with a barometric damper. I will approach my trouble shooting with your ideas in mind.
  • John Abbott
    John Abbott Member Posts: 355
    Make sure you have the correct nozzle and specified pump pressure go by what Beckett specifies for that boiler burner combo.
  • Richtdow
    Richtdow Member Posts: 22
    John, this is the burner specified for the boiler. As far as checking and adjusting the pressure, I‘ve read to leave that alone if you don‘t have experience with it. I‘ll research checking it.
  • SuperTech
    SuperTech Member Posts: 1,919
    First thing I would do after making sure that the combustion analysis and draft settings are to the manufacturers specifications is test the oil pump cut off. If you are running your burner at 100 PSI the pressure shouldn't drop more 20 PSI after closing the valve on the pump testing manifold gauge.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,132
    Shouldn't you check the pump before doing a combustion test?
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 5,632
    Unless the control was replaced, the Genysis control indicates there is most likely a Clean Cut pump. This will shut of oil to the nozzle at 90% of operating pressure. Here is a picture of how to check pump pressure and fuel cut-off. (See the gauge attached to the high pressure line in the pic?)

    Every oil heat mechanic that I trained had a gauge set up like this.
    (I would take a picture of my gauge but it is not here now!)
    Connect the 3/16" flare fitting and attached to the high pressure line from the pump. Operate the pump. Read the pressure. After safety lockout (15 seconds) read the pressure. It should drop about 10% to 20% then hold for 15 minutes. If it does not hold, the fuel cut-off is passing. There is the source of the after drip!

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Richtdow
    Richtdow Member Posts: 22
    Thank you for the input!
    HVACNUT Member Posts: 5,026
    edited December 2019
    The Yellow Jacket 78020 is nice for checking pressure.

    I've had this Kwick- Check gauge for forever and a day. It's showing a J pump. Still accurate.
    Inline to check, adjust pressure and cut off while the burner is running.

    I've got a Riello manifold that checks pressure and vacuum at the same time. That's a time saver.