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Burnham Boiler limit switch not working

Co
Co Member Posts: 8
in THE MAIN WALL
Have a Series 2 Model B gas boiler. Was originally set up as one zone with the built in circulator wiring in the boiler. I now have two heating zones through a taco and heat distributed through the air handlers. All thermostats are wired correctly and working properly. However the limit switch will not turn the bolier off despite it being set at 140 degrees and the bolier is running at 170. The plumber installed a new limit switch this morning. When i pull the limit switch manually the boiler will shut down so i'm assuming the relay is in proper operation. Thanks for your help.

Comments

  • Gordan
    Gordan Member Posts: 891
    Not sure I understand

    Are you talking about the boiler high limit? It should not be set to 140. Your boiler will rust to pieces.
  • Co
    Co Member Posts: 8
    reply to question

    Yes, the high limit switch that senses the internal water temperature in the boiler. I just turned it right down to 140 degrees to test the operation of the limit switch, The boiler gauge showed 170 degrees yet the limit switch did not break contact.
  • Gordan
    Gordan Member Posts: 891
    Maybe the sensing bulb doesn't have good contact?

    It needs to be properly inserted in the immersion well.
  • Co
    Co Member Posts: 8
    making contact

    Thanks Gordon. When i remove one wire from the limit switch the boiler automatically shuts down. So it has to be either it is not making proper contact or is it possible that the plumber did not properly fill the boiler with water so it's simply not sensing the water temperature ?
  • Paul48
    Paul48 Member Posts: 4,469
    Does

    This boiler have the optional dual limit. One inside the boiler and one in a tee on the supply. If so....if the one in the boiler fails and it is using the one in the supply only, it will overshoot.
  • Co
    Co Member Posts: 8
    answer

    It doesnt have additional limit Paul. Just the one built into the boiler
  • Paul48
    Paul48 Member Posts: 4,469
    Of course not

    That would be too easy.. :-)
  • Paul48
    Paul48 Member Posts: 4,469
    2

    limits, same results.......I'd question the temp gauge.
  • Co
    Co Member Posts: 8
    reply

    I assumed that too.But the plumber purchased and installed a new one this morning. The boiler was existing in an extensively remodelled house. It's situated in boston where it was very cold last week and the boiler hasn't been operational until today this winter. Do you think it is possible that the well the temperature gauge is installed in cracked or something due to the freezing temperatures? Thus causing it to be unable to monitor the temperature? Thanks
  • Co
    Co Member Posts: 8
    reply

    I assumed that too.But the plumber purchased and installed a new one this morning. The boiler was existing in an extensively remodelled house. It's situated in boston where it was very cold last week and the boiler hasn't been operational until today this winter. Do you think it is possible that the well the temperature gauge is installed in cracked or something due to the freezing temperatures? Thus causing it to be unable to monitor the temperature? Thanks
  • Paul48
    Paul48 Member Posts: 4,469
    Both

    He replaced the hi-limit and the gauge?
  • Co
    Co Member Posts: 8
    high limit only

    Sorry Paul,read your last post wrong. he just replaced the high limit switch. Not the gauge. Though the gauge does seem to be operational. we turned the boiler off for a few hours and the gauge went to the bottom. When we turned the boiler on again the gauge started rising again
  • Paul48
    Paul48 Member Posts: 4,469
    Operational

    Yes, but maybe not accurate.I'd bet the boiler manufacturer doesn't install the highest quality.
  • Co
    Co Member Posts: 8
    gauge

    Thanks Paul. I'll maybe run the boiler for a hour in the morning and see what the gauge gets to and see if it will shut off.
This discussion has been closed.

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