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Pressuretrol at .5oz boiler not turning on

JH3550 Member Posts: 13
I recently moved into a house built in 1924 with single pipe steam. I read Dan’s “We Got Steam Heat.” He says to set the pressuretrol cut in to .5 and the differential to 1. When I do that, the boiler does not turn on when the thermostat calls for heat. I have to raise the cut in to a little under the 2 line for it to turn on. 

Is there something wrong with my pressuretrol or something else in the system?

FWIW the system does not have functioning main vents. I’m hoping to have them installed. 

Thank you for all of the knowledge and information you all share here. I’m leaning a lot!


  • dabrakeman
    dabrakeman Member Posts: 526
    Pressuretrols are not very accurate but you won't really know what is going on until you do two things. 1) make sure your pigtail is clean so the pressuretrol can see the actual pressure and 2) add a low pressure 3psi or 5psi gage that can actually react to the low pressures.

    The best I could do with mine is just barely under 2psi cutout per my 3psi gage.