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Erratic Munchkin Boiler

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MikeG
MikeG Member Posts: 169
in THE MAIN WALL

Been awhile since I've posted. I have a Munchkin 80m boiler on LP, 925 controller, Amtrol TD1L indirect for domestic, 3 zones finned baseboard and a small radiant zone all thru Taco SR 506 relay with pumps. On a call the boiler fails to ignite all the time. Fan runs it tries multiple times, then locks out. It does not show any error codes. Spark gap is correct. If it does fire it doesn't reach high limit and shuts down, then tries to restart and goes to lockout. If I turn power off and wait it may fire again. Any ideas or what to check is appreciated. Thanks Mike

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,734
    edited 4:52PM

    Flame signal

    Look closely at the failures. Is there a flame and then it goes off?

    Since it has been some time since I worked on a Munchkin, can you tell me: is there a spark to the main burner or a spark to a pilot?

    If it is a spark to a pilot, look to see whether there is a pilot flame that comes on, goes out, and then tries again. If the pilot flame appears and then goes out right away, the flame signal is not getting through to the ignition control.

    Here are my steps for the repair:

    1. Clean the flame sensor.
    2. Verify ground connection from sensor to control ground. (ask me how if needed)
    3. Replace the flame sensor.
    4. Replace the sensor wire.
    5. Replace the control.

    That goes from lowest cost to highest cost until you get it to operate without a failure. Hopefully just polishing up the flame sensor with emory cloth or steel wool will solve the problem

    If there is NO FLAME on trial for ignition, then we look in a different direction.

    Edward Young Retired

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

  • JUGHNE
    JUGHNE Member Posts: 11,635

    Has the front cover been taken off and the inside coils cleaned?

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,862

    Check the condensate path. I bring an air compressor with me on Munchkin calls to backflush the condensate drain as the trap often gets clogged after all those years.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab

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