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Here's a teaser for you all . . maybe Dan will even answer!

Daniel_3 Member Posts: 543
So my pressuretrol from Gm Delco was at around 6psi's for about a two-year period after I bought this house. After learning a bit more about residential steam one-pipe heating systems I figured " Wait a second, 6psi's is way too high! I need to turn this pressure downtown!" So I put my cut-in at .5 psi (lbs) and my diff. at 1 psi and everything was fine and dandy for about two weeks. All of the sudden I took a look at the thermostat one day and "Hold on, why is the ambient temp at 63^ and the request is at 65^, uh oh!". So I ran donw to the cellar and I hear that nice whoosh coming from the boiler and checked and "LO! the pilot's on!". So then I went to the thermostat and played with the request temp bringing it down to below ambient until the audible click and then back up again to the audible click above ambient and then the boiler fired up . . . .Maybe my thermostat is bummy . . So I bypassed the thermostat after this happened three or more times in a week period to check and hmmmmm, no fire up on the boiler. "I hope my boiler is not having a premature case of cold skin." I them remembered the pressuretrol "Ding!" So while the thermo was bypassed I turned the cut-in pressure up about 1.5 more psi's and "Whoosh!" there she fires. As I speak the thermo is still bypassed and the boiler is burning . . . .

Who can tell me what happened or is happening?


  • Techman
    Techman Member Posts: 2,144

    It might be the face value of the control is slightly out of calibration.Reconnect the stat and wait!
  • Daniel_3
    Daniel_3 Member Posts: 543

    Possible. When I turned the cut-in up that 1.5 psi's the mercury tube jumped to the right more than it seemed it should have moved. Could it have been stuck maybe to change the calibration?
  • The mercury tube,,,,,,,,

    is like a "teeter-totter", and your adjusting the spring tension pull on 1 side, if it "acted strange" check the "pigtail" below-it for crud blockage.

  • Long Beach Ed
    Long Beach Ed Member Posts: 1,188

    The pressurtrol may be out of wack, but more often than not the pigtail is full of crud. This traps pressure in the control and makes it operate strangely.

    You may bust the pigtail if you try to unscrew it from the boiler. Be careful. Take the control off it and try to blow it clean into the boiler. If that doesn't work tap it with a hammer and try unclogging it with a wire.

    If you can't blow through it, you found your problem.

    Long Beach Ed

  • Daniel_3
    Daniel_3 Member Posts: 543

    Great! I'll try that and if it doesn't work then I'll bite down on the mercury capsule until it breaks =)
This discussion has been closed.