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Boiler continuously refiring

My boiler turns on and off many times during the heating cycle. I was told to check the boiler's heat exchange device to see if it is blocked. Where is the heat exchanger? Could it be that the spill switch is the wrong celcius rating for the boiler. I own a Dunkirk Plymouth II, intermitent ignition series PBS51.

The spill switch in place right now is 152C. I have a variety of them ranging from 144C to 240C.
Also I wondered if there are too many 90 degree turns in the piping that leads to the outdoors. Maybe the updraft is inadequate. Please see pictures.


  • Jamie HallJamie Hall Member Posts: 14,836
    Are you sure that it's the spill switch that's tripping? Because, if so, it's likely that there is something wrong with the draught -- but it could be any number of possibilities.

    If it is the spill switch, though, that must be cured and unless the switch is actually defective, it is telling you about a potentially very dangerous condition, and it should be checked and remedied by someone who really truly knows what they are doing.

    You should invest in a good CO monitor and install it nearby...
    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
  • heatseeker1heatseeker1 Member Posts: 72
    Hi Jamie. Thanks for the advice regarding the CO monitor. I installed one in October 2015. On the matter regarding my spill switch, I was never told that it was the spill switch, I was just putting that out there just to get an opinion about whether the voltage limit of the spill switch could hinder the efficiency of the boiler.
  • STEVEusaPASTEVEusaPA Member Posts: 4,720
    What's the pressure doing while it's cycling. Maybe check the pressuretrol/clean the pigtail
  • todd_ecrtodd_ecr Member Posts: 91
    I doubt it's the spill switch. That would require a manual reset. It's likely either cycling on the thermostat, pressurtrol, or the LWCO

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