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Beckett Pre-Purge Power Cycling

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Etuuq
Etuuq Member Posts: 2
in Oil Heating

Got a Beckett AFG Oil burner on a Weil Mclain Boiler. My neighbor was having some trouble with an oil leak that looked to be coming from the pump shaft. After finding a real gummed up nozzle, I decided to open the boiler up and the thing was damn near completely clogged with carbon build up. So I cleaned that all up, installed a new nozzle, repositioned electrodes, and cleaned the cad cell. No more oil leak. I Went to turn the thing back on, and I'm getting this power cycling every 2-3 seconds on the pre-purge. It's like it's losing power for a half a second, every two seconds. It'll keep on doing that over and over and over, and not even trip a lock out. If I open up the transformer, the cycling will stop, and I can see the fan is spinning strong. Open the fuel bleed screw, and there's plenty of flow. Then if I lower that transformer lid back down onto the electrodes there's plenty of spark. If I keep the transformer springs off the electrodes for at least 15 seconds to complete the pre-purge cycle, I can shut the transformer lid and the boiler will fire, but only for about 2 seconds before it starts cycling again. Can't get a steady fire AT ALL. According to my neighbor, everything was running fine before I touched the thing haha (minus the fuel leak). Any ideas? Fuel solenoid? Primary Control?

In a different forum, I got 3 answers telling me to call a contractor. When I explained that I live in a remote Alaskan village (we don't even have a store), I was told they weren't allowed to advise DIY'ers. So if I can't get advice, I'd really appreciate some thoughts on what you think might be going on. Is the Primary Control wiggin out? You'd think that the cycling would cause a lock out.

Comments

  • 109A_5
    109A_5 Member Posts: 4,110
    edited April 25

    Do you have a multimeter ? I'd check the power. It seems with the load of the ignition and/or when the oil solenoid valve energizing causes the system to brown out causing the cycling.

    Check for loose connections L1, L2, Limit.

    Hot water boiler ? Is there a Honeywell Aquastat ? If so the solder joints where the relay connects to the board go bad.

    Boiler model, primary control model ?

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • pedmec
    pedmec Member Posts: 1,393

    Double check you electrodes. Spark could be jumping to the burner head instead of between the electrodes

  • Steamhead
    Steamhead Member Posts: 18,547

    Also, the CAD cell might be going bad.

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • MaxMercy
    MaxMercy Member Posts: 605
    https://forum.heatinghelp.com/discussion/204292/beckett-pre-purge-power-cycling

    My guess is that your electrodes are too close together or too close to the nozzle causing an overcurrent detection of the ignitor in the control. I'm not sure if the control watches things like secondary ignition overcurrent, but I would try repositioning the electrodes according to the Becket specs.

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,322


    Your problem is in the Primary Control. That would be the control with the reset button. Can you provide the model number of that control? Beckett has one called GeniSys. There are several models of that control:  7505B1500U, 7505A0000U, 7505P1515U, 7505P1530U and several more

    Honeywell may also be on the burner : R8148G????, R8184M1051, L7184????, R7284B1024, R7284U1004, and many others.

    There are Carlin and ICM that also make a control that you might have if that control has been replaced since the boiler was installed.

    Please tell me the part number or at least a photo of the primary control and I can help you with this problem

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • HVACNUT
    HVACNUT Member Posts: 7,478

    Everything is breathing so much better since its been cleaned.

  • Etuuq
    Etuuq Member Posts: 2

    Big Thanks Everyone… Electrodes were off - not by much - but readjusting them did the trick. Those little metal T501 tools aren't my favorite. Online today I saw the Z2000 that you just slip onto your nozzle. Looked pretty slick to me. Most people in our village run Beckett AFG's. Think I'll order one or two Z2000's.

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