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Pigtail plugged or Pressuretrol issue? Both?

ksmith Member Posts: 3
Williamson gas boiler installed a little over two years ago. The pigtail was checked recently during a service call, but am I right in thinking that either a blockage is preventing the pressuretrol from getting a correct reading, or the pressuretrol is not responding as it should once the pressure exceeds the cutoff? The diff is set at 2. I understand that the 30psi gauges aren't that accurate at the low end of the scale, but I don't think its wrong about the pressure being higher than it should be.

Thanks -


  • Jamie Hall
    Jamie Hall Member Posts: 21,090
    Actually, given the setting on your pressuretrol, the gauge may be almost correct if that picture was when it shuts off.

    The way you have it set it should cut out at 4 psi and cut back in at 2 psi. Both of those, as you know, are too high.

    Try setting the interior dial -- the differential -- to 1 instead of 2, and the exterior slider (the cut in) to just above the 0.5 (bottom) mark.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ksmith
    ksmith Member Posts: 3
    Thank you for the quick response - I'll make those changes.
  • ksmith
    ksmith Member Posts: 3
    The system is serviced annually by a local company that specializes in steam systems (found them here, actually) and they've been very tolerant of my questions while they work. Last full maintenance was in July 2022, but just last month I had the plumbing company that installed the system out to diagnose a problem with the indirect hot water system, and that technician checked the pigtail and pressuretrol, or said he had.