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Steam boiler PSI at 4 but pressuretrol at 1.5 cut off

I had noticed that my gauge on my boiler goes up to 4 PSI before cutting out (before target temp hit at the thermostat). The Honeywell pressuretrol is set to cut in at the lowest setting 0.5 PSI with differential 1 PSI so I would anticipate it cuts out 1.5 PSI, but the gauge suggests it cuts out at 4. The oil company maintenance man said that these pressure gauges break quickly and so it is not worth to get a new one and that the pressuretrol is working appropriately since it is cutting out.

It sounded wrong to me so I wanted to get your opinions on what to try first (ie swap out gauge or pressuretrol, or consider something else)? Thanks


  • ethicalpaul
    ethicalpaul Member Posts: 5,702
    He's not wrong, those gauges fail fast. But he is wrong that it's not worth it to get a new one...but what you do is you get a new 0-3psi gauge and put it on a tee with the pressuretrol.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,204
    Many type pressuretrols are very inaccurate also. Before replacing anything, check that the pigtail, which protects the control from steam, is not clogged. They tend to clog with sludge which blocks the pressure flow.
    EBEBRATT-Ed Member Posts: 15,532
    Then after cleaning the pigtail put on a new 0-30 psi gage and a new 0-5 psi gauge. Put a valve under the 0-3 gauge (no valve under the 0-30) and only open the valve on the o-3 when checking the pressure or adjusting the controls
    Long Beach Ed
  • bkselly
    bkselly Member Posts: 19
    Thanks all!
  • EStark
    EStark Member Posts: 18
    I'm guessing the valve at the bottom of the 0 to 3 is the help from it going bad prematurely,  Keeping it isolated from the system when you don't need it ?
  • Waher
    Waher Member Posts: 251
    The valve is so that if your boiler exceeds 3 PSI unattended that the pressure dial doesn't get broken by the overpressure. When you watch the 3 PSI dial with the valve open the pressuretrol should shut the system off at 1.5 PSI, and if it doesn't you should close the valve before hit hits 3psi and shut down the boiler.