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Old Mini Therm II not shutting Down

Had to repair a bad pump and a blown line. Now the boiler will not shut down when it gets to the high limit. Checked the limit switch and it's breaking contact, if I pull the MV socket the boiler will shut down, but other wise it just keeps heating up until I shut it down manually. Ideas, Please?


  • Jamie HallJamie Hall Member Posts: 12,947
    Hopefully somewhere in the wiring from the limit switch to that socket there is a short. Or it got mis-wired somehow.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ZmanZman Member Posts: 5,870
    edited December 2019
    There was a period of time when Teledyne Laars employed an absolute psychopath to install zip ties on the control wires. I have seen them so tight they crushed the insulation and shorted the wires. I would try turning it all power off, cutting the ties and inspecting the wiring.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    delta Tkcopp
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