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Minuteman II

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bagcag02
bagcag02 Member Posts: 3
in Gas Heating
I am working on a Burnham Minuteman II. Model MMII4-105P. Problem is while the unit is operating, the inducer shuts off and the flame goes out. within about one second it starts the cycle again to start and will run for a while then shut off, then right back on again. This is what i have found. I jumped out the exhaust temp probe and it operates without shutting off..Of course I changed the probe (this is after a lot searching and studying the schematic). Same problem. Jump it out and it works fine. I have not yet called Burnham. I'm looking for other insight before I call them. BTW... cell service is almost non existant at this place and there is no land line. Country cabin in the woods. Domestc water is not connected.

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  • M_Smith
    M_Smith Member Posts: 6
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    If you jumped the flue sensor and it worked fine, replaced it and had the same problem your new sensor is likely a dud.

    I would check for a flue blockage just to be sure (though that's not likely).

    It's usually that sensor and jumping it is the test. I have enough of those in my area that I stock a sensor.

    Matt
  • bagcag02
    bagcag02 Member Posts: 3
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    The boiler was used and the customer brought it to his house. I installed it. The flue is clear and the venting is new. The original probe was replace. Then the replacement probe was replaced. All doing the same thing. Jumped out...it works fine.
  • M_Smith
    M_Smith Member Posts: 6
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    weird. your pulling the wires off the flue sensor and jumping those, or jumping somewhere else? and just to confirm the sensor we're talking about is up under the top cover, on the right side of the inducer box. probably 4 inches long?

    There's only a few safeties, flue temp, water pressure (they were originally not to be used with an auto-fill), roll-out switch (just outside combustion chamber), and the differental pressure switch. They are all in series, so if it runs normally when you jump it, maybe you got 2 duds??
  • M_Smith
    M_Smith Member Posts: 6
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    is it a burnham specific part, or generic replacement, wonder if you were given the wrong heat range part?
  • RobG
    RobG Member Posts: 1,850
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    I would suggest temporarily jumping out the flue sensor and putting a combustion analyzer on the unit. The temp sensor is a safety device so should be treated as such. Do not run the unit without solving the underlying issue.
  • bagcag02
    bagcag02 Member Posts: 3
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    To answer all the questions...I jumped the flue sensor at the sensor. It is attached to the inducer box and is about four inches long. I believe it is a Burnham specific part. All the sensors look identical with the same temp rating and same part numbers on it. I put in a k type thermocouple to check temp at the flue collector. averaged 460 degrees. sensor set for 600degrees.

    I'll try another sensor and a combustion anaylizer. Just so i'm on the same page as you guys are, what are the o, co, co ppm, etc., numbers supposed to be for this unit?

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