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fuel oilleaking from chamber door

hello...I need some help....I installed a burnham MPO_iq 3 pass oil fired boiler. It came with a becket AFG burner setup with a 7184 digital primary control. Within 1 minute of operation I noticed oil dripping from the bottom of the chamber door. I shut off the burner and checked the nozzle assembly. It appeared fine. It is an L2 head with a .65gal-35w nozzle. The Z dimension was checked with the conical head distance to be 1"3/4 all good. It is a 2 pipe system and a bypass plug was installed in the return port.
after several attempts to run the boiler, fuel oil drips out of the bottom of the chamber door as well as at the attachment flange of the burner to door. The blast tube showed signs of excess oil and after shutdown the entire hinged door interior face was on fire for 10 minutes. I changed the nozzle and rechecked the turbulator head to seat against the shoulder of the nozzle fitting. What is causing this excel oil. Could the nozzle gun be defective and leaking. One day old installation.
Thanks Ben


  • JStar
    JStar Member Posts: 2,752
    Bad thread on the nozzle tube? A crack somewhere?
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    This could be a few things. You said it was 2 pipe, are you sure the bypass plug was installed in the return port, and the return line isn't/wasn't blocked? I would get rid of the bypass plug and the return line. If the return was blocked, even for a few seconds, the pump seal would be destroyed.
    I would first put in a new proper sized nozzle, making sure not to over tighten. Make sure all fittings are tight including the oil line connections into the bottom of the pump cover.
    Then I would remove the return line & the bypass plug, plug the port and do a proper pressure/cutoff/vacuum check off the pump.
    Then check the transformer.
    Then make sure the delay valve wasn't allowing oil into the chamber during pre-purge.
    If all of those checked out, I would reassemble everything and fire it up.
    You can SLIGHTLY crack the inspection port open to see if oil is spraying during pre purge, and to see the initial light off. Remember it's positive pressure over the fire so I usually hold the inspection door slightly open with a screwdriver so I can immediately push and hold it closed if need be.
    If it's still blowing out oil, or not lighting off, then one or more settings are off-air band, z dimension, too much over fire negative draft etc.
    If it appears to be working for a minute or so, then you'll need to do a full combustion test.
    Let it run a good 10 minutes, and adjust the draft at the rear test port to zero, or as close to zero on the negative side as possible. I need 2 draft regulators on mine to achieve this. The over fire will be positive.
    Then close the air band, first 2 numbers, and do a proper smoke test. Keep closing, if necessary until you see smoke on the paper. Then slowly open air band one number at a time until the paper is clear.
    Then stick the analyzer on it. After the analyzer stabilizes, note the CO2 number, and open the air band until it drops 1 percent.
    Proper smoke test method:
    1. Put a piece of test paper in the gun. Put your finger over the end of the hose, and pull the plunger about an inch. The plunger should hold. If not the gun needs to be checked/fixed.
    2. In the flue pipe, pull the plunger. Should take 3 seconds per pull, holding for three seconds. Push plunger back in and repeat a total of 10 times.
    Most people go to fast and end up leaving the burner at a 1 or 2 smoke.

    There was an error rendering this rich post.

  • enalkarion
    enalkarion Member Posts: 7
    I had a similar problem and it ended up being a hairline crack in the nozzle tube causing what your describing. when the nozzle was installed was it snugged and not cranked down on possibly stripping it? Maybe wrong spray pattern on the nozzle?