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Pop off valve

Cahill Member Posts: 4
What might cause my pressure relief valve to vent. I just started the boiler up for the season and I heard the valve blow off after about 20 minutes


  • BobC
    BobC Member Posts: 5,473
    Shut that boiler off!

    That valve is set to pop at 15PSI or more, if it went off you have a serious safety issue. The normal operating pressure of a steam boiler is less than 2PSI.

    The most probable cause is a plug in the pigtail between the boiler and the pressuretrol or vaporstat; it's the curly pipe below the gauge and vaporstat in the picture. If you are handy you can clean or replace that pigtail yourself BUT DON"T OPERATE THE BOILER TILL IT'S FIXED. The pressure relief valve will have to be replaced also, they become unreliable once they pop off.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Cahill
    Cahill Member Posts: 4
    Pop off valve

    I will follow your advice thanks !
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