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Munchkin M80 Problem

Keith Brown
Keith Brown Member Posts: 4
I have a Munchkin 80 LPG that has light off problems. It will only start when cold if there is a strip of tape across the air inlet to the blower. Gas pressure on the inlet side is 11 In.W.C. And there is only 1/2 In. W.C. pressures drop on start up. CO2 is at 9 1/2% and adjusting it to the high side had no effect on cold start up. The combined vent is 26 Ft. I can’t leave the tape on it forever.
Any suggestions are greatly appreciated?
Keith

Comments

  • Keith Brown
    Keith Brown Member Posts: 4
    Munchkin M80 Problem

    I have a Munchkin 80 LPG that has light off problems. It will only start when cold if there is a strip of tape across the air inlet to the blower. Gas pressure on the inlet side is 11 In.W.C. And there is only 1/2 In. W.C. pressures drop on start up. CO2 is at 9 1/2% and adjusting it to the high side had no effect on cold start up. The combined vent is 26 Ft. I can’t leave the tape on it forever.
    Any suggestions are greatly appreciated?
  • RichW
    RichW Member Posts: 28
    Munch

    Does it make a rumbling noise at the same time that the burner goes on and off?
  • Keith Brown
    Keith Brown Member Posts: 4


    It fires fine with the tape and does rumble a little without.
  • Keith Brown
    Keith Brown Member Posts: 4


    It fires fine with the tape and does rumble a little without.
  • RichW
    RichW Member Posts: 28


    I found a strange problem this past Saturday. Look at the brass regulator vent on the gas valve. Is it touching the back wall of case? Mine was very close. I took a screw driver and pushed back on the case, leaving a larger gap between it and the vent. Magic- the boiler fires and runs fine. I removed the brass vent and drilled a .5 inch hole where the vent was touching. After replacing the vent the cust. said it was the smoothest sound the boiler ever made.

    Good Luck, hope this helps.
  • Doug_7
    Doug_7 Member Posts: 233
    Munchkin M80 Problems

    I am not a munchkin expert but this is my best guess based on the symptioms you describe.

    There is usually a "Prove Air Flow" pressure-switch in the control logic. When the combustion air blower starts and the air flows, the "Prove Air Flow" pressure-switch will sense this and pull in, "proving" there is an air flow. This is necessary to allow the start-up sequence to continue. If there isn't enough pressure-difference to pull in this pressure switch, the start-up sequence is terminated.

    This is why there is usually a minimum pipe length specified for the inlet air and flue piping. There needs to be some piping length to create enough pressure-difference due to the air flow, to pull in this pressure switch.

    Check that your inlet air pipe simply isn't too short. I suspect the tape is adding just enough pressure-difference to pull in this pressure switch.

    Check the Munchkin manual. Is this a new installation ? What is your inlet air pipe length ?
  • Chuck Shaw_2
    Chuck Shaw_2 Member Posts: 68
    Give us a call

    Keith

    Give us a call here at the tech support office, 1-800-323-9651 ext 25 and we will help you out

    Chuck Shaw
    Technical Support Department
    Heat Transfer Products
  • Doug_7
    Doug_7 Member Posts: 233
    What was the problem ?

    Keith - Please tell us what the problem was and how it was fixed.
This discussion has been closed.