Pressuretrol with DO NOT ALTER sticker

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steamkevin
steamkevin Posts: 12
in Strictly Steam

Hello, I'm working on optimizing a ~15 year old steam system and the pressuretrol has a warning "The main scaleplate has an installed SAFETY STOP. DO NOT ALTER."

Based on what I understand though it is set too high and should be dropped down to Main 1.5 PSI and Diff 1 PSI.

Is this just a manufacturer deterrence sticker? Are my PSI settings correct?

IMG_4358.jpeg

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  • bburd
    bburd Posts: 1,340

    The safety stop is that blank screwhead at the top of the main scale. It prevents the pressure from being set higher than 10 psig. That's way too high for your system anyway. The warning is to prevent someone from removing the stop and setting it even higher.

    That is a subtractive pressuretrol, so the main scale sets the cutout (maximum) pressure and the differential controls the cutin.

    If this is a standard low pressure steam heating system, the cutout should be no higher than 2 psig and closer to 1.5 if possible, with the differential at 1. These controls are often not well calibrated though, so you may have to experiment. Unfortunately, the 0 to 30 psi gauge required by code is not usually accurate at these low pressures.

    —
    Bburd
    steamkevin
  • steamkevin
    steamkevin Posts: 12

    Ah thank you for pointing out the screw! Yes this is a standard residential one pipe steam system.

    I’ll be adjusting this to about your suggested ranges.

    bburd

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