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The Mystery nobody can figure out

JEMM55JEMM55 Member Posts: 47
Intermittent Pilot Ignition

I still have this problem and it seems nobody can figure it out..

Ultimately I will be changing to a new powerflame burner due to this MYSTERY!!!

Loss of pressure across pilot solenoid

I have a Weil McClain model 580 with a Midco burner.

I am having a problem with the pilot.... it lights only intermittently when the boiler calls for heat or hot water.

Everything is freshly tuned...ignition, flame rod, all electronics ignition check out and there is excellent spark

The main gas pressure is over 6in col water. The pressure before the solenoid is also 6 after a 30 inch run past the regulator. The burner calls for 3.5 in column after the solenoid. BUT....No matter what I do the pressure drops to 1.8 max.

New solenoid, proper electric feed, everything clean but can't get higher pressure so the pilot is lighting only intermittently.

This is the mystery nobody can figure out...Any ideas are


  • JStarJStar Member Posts: 2,668

    What model burner?

    Have you checked if the pilot tap on the gas cock is blocked?
    - Joe Starosielec
    [email protected]
  • JEMM55JEMM55 Member Posts: 47

    Everything is clean...pilot lights outside of the boiler when tested.

    Gas pressure is the problem

    We thought of underpowered solenoid, blocked line...still no dependable pilot.

    Always lights after several attempts....once enough gas gats into the system....

  • billtwocasebilltwocase Member Posts: 2,385

    that the boiler is blocked?. Just a thought
  • JStarJStar Member Posts: 2,668

    I would check for proper amp draw through the solenoid. You may be getting the right voltage, but not enough amperage to fully open the valve.
    - Joe Starosielec
    [email protected]
  • icesailoricesailor Member Posts: 7,265
    I would also:

    Try jumping out the solenoid with an alternate power source to see if you still get the low gas pressure when the solenoid opens. You say that the pressure is sub-specs when the control opens it. How about when YOU tell it to open? Like someone just said, maybe the power from control isn't correct.

    Just a random thought.
  • SteamheadSteamhead Member Posts: 11,328
    Is there

    a pressure regulator or other adjustment in the pilot gas line?
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • icesailoricesailor Member Posts: 7,265
    edited November 2012
    Again I ask,

    I was confused with another posting.

    The below does not apply to this situation.

    Again I ask, was the burner converted from Nat Gas to Propane? If it has the proper LP pilot orifice, and the gas valve is running under Nat Gas pressure, the pilot orifice is too small for the pressure and the pressure would drop like described.

    If it's LP. shouldn't the gas pressure to the valve and the pilot orifice be 10" WC+? Do I remember that it was 3.0+ WC and it drops?

    Whatever is wrong is stupid. Something is being over thought

    Back to basics.
  • JEMM55JEMM55 Member Posts: 47
    Natural conversion....

    Still a mystery...the pilot orifice is not the problem!
  • unclejohnunclejohn Member Posts: 902
    Electrod problem

    Are you measuring gas pressure after the valve on the burner side? I doubt you need 3.5 to the pilot. You may be arcing your spark to the inside of the boiler some where other then the electrod. You say it lights fine outside the boiler correct?
  • JEMM55JEMM55 Member Posts: 47
    The electrode is at spec...spoke to Midco who says 3.5c.w. is correct.

    The electrode on the end of the gun is in front of the orifice for the pilot and without the correct pressure it wont light
  • JEMM55JEMM55 Member Posts: 47
    And there is no way to change the orifice as it is directly part of the gun

    Therefore you cannot change the pilot orifice. Just not enough pressure.
  • JEMM55JEMM55 Member Posts: 47
    And there is no way to change the orifice as it is directly part of the gun

    Therefore you cannot change the pilot orifice. Just not enough pressure.
  • ZmanZman Member Posts: 3,478
    tunnel vision

    Please map out your system for us. What controls the pressure to the pilot? How have you determined the pilot is correct and is not leaking? All mystery problems have one thing in common. The true cause was prematurely eliminated.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • icesailoricesailor Member Posts: 7,265

    And one problem I have seen is leaking compression fittings on aluminum tube. I always lube the stuff with something as a lubricant/ Like Rectorseal #5.

    I made up a "Rig" with a LPG outside regulator that drops the pressure to 11" WC and I can connect to my air compressor and connect it into a gas line going to a burner or whatever and not ruin the gas valve. A clever person could figure out a way to jump out controls and make a gas appliance run and instead of gas to the burner, you have low pressure air. You can then look for leaks. Without blowing yourself up.

    No testing with live gas for this chicken. A couple of Presto-Taps and a refrigeration hose is a wonderful thing.
  • JEMM55JEMM55 Member Posts: 47
    Pulling it apart tomorrow

    Maybe this is being overthought.

    Something has to be up with that run from the solenoid to the pilot.
  • unclejohnunclejohn Member Posts: 902
    Thi is a clue


    Everything is clean...pilot lights outside of the boiler when tested.

    Gas pressure is the problem

    How can it for sure be gas pressure if it lites fine outside the boiler?
  • mystery

    is there a reverse draft in the chimney, blowing out the pilot?--nbc
  • Mad DogMad Dog Member Posts: 3,171
    Timmie Mc Elewain will

    solve that.  Mad Dog
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • JEMM55JEMM55 Member Posts: 47
    Not the draft

    Pilot does not blow out.

    Requires multiple starts to get enough gas to light the first time.

    Not enough gas
  • RJRJ Member Posts: 483
    pipe size

    check your gas main to boiler is it the proper size, per burner manufact. is any thing else on that line like domestic hw or hvac equip. ?  If your burner is 580 mbh than you most likely need around a inch and a quarter to inch and a half line depending on how far from gas reg.  also check gas reg make sure orfice is the right size. I would also check the burner plate for cracks or to see if it is warped.
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