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Mercury Switch Pinned But Boiler Not On

I suggest that you post this on the main part of The Wall so that some of the steam guys see it. Someone will know.


  • Tom_105
    Tom_105 Member Posts: 2
    Mercury Switch Pinned But Boiler Not On

    A few times lately my big old residential steam boiler has failed to respond to a call for heat. The problem is intermittant.

    Upon investigation, I've found the mercury switch in the pressuretrol tilted all the way towards the on position but the boiler was not on.

    I manually tilted the mercury switch to the off position by hand and let it spring back to the on position and the boiler fired up. It seems like a dirty contact or something. How can I fix this?
  • heatguy
    heatguy Member Posts: 102
    clogged pigtail

    pressure control should be screwed onto what we call a pigs tail[cause it looks like one]may be clogged if its steel you should replace with brass they clog less.reread your post more then likely you are doing a low voltage reset when you toggle the mercury something wrong in ignition cycle?
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