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General Pressuretrol Question


During testing of my radiator vents, I've noticed that when my boiler is running to take the thermostat from 64->67, the gas/boiler is on consistently throughout the entire time (which could be a good 40-60 minutes or so). Is this normal? Or should I expect the pressuretrol to kick in at some point and turn off the heating element? I am not really sure if that's what the pressuretrol is responsible for, but that's my assumption. The needle on my PSI gauge never moves at all.


  • BobC
    BobC Member Posts: 5,401
    if the boilers steam making ability is closely matched to the radiators you may never raise any appreciable pressure unless your coming back from a deep setback (6-10 PSI).

    Does the needle on the gauge twitch at all towards the end of the steaming cycle? Do you hear any loud hissing from the vents? If you do hear load hissing there is a chance the pressure gauge is not working OR your main vents are too small.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • mcvetyty
    mcvetyty Member Posts: 50
    Thanks Bob - Zero hissing at all on my system. I haven't watched the pressure gauge near the end of the cycle, but will make a point to next one!
  • Fred
    Fred Member Posts: 8,541
    It sounds like your boiler may be well matched to your radiator EDR. That is a good thing. The only time the burner should shut down is when the pressure gets higher than your Pressuretrol is set for, The water level, in the boiler gets to low or the thermostat is satisfied. In the case of the pressure, recovering from a deep setback and/or extreme cold may cause the boiler to run for extended periods and it may build pressure. Low water is not good and the cause needs to be explored. Satisfying the thermostat is what you want. Having said that, do you have a 0 - 5 PSI pressure gauge on the boiler? If not, you should add one as the 0 - 30PSI gauges hardly move enough for you to see what is actually going on, pressure wise. The fact that you don't hear any hissing is also a good indication that pressure is not building in the system.
  • rrwitherspoon
    rrwitherspoon Member Posts: 104
    what causes pressure to build in a system?
    can a temporarily disconnected large radiator cause this. Hardwood floor replaced. Steam pipe was noted to be pitched in properly before closed up. Worried that supply valve will not line up at correct level.
  • Fred
    Fred Member Posts: 8,541
    Lots of things. The most common ones are bad near boiler piping, a boiler that is significantly over sized for the square feet of radiator EDR, either because it was to large when purchased or a number of radiators were removed over the years. Poor venting on the mains is another big cause and one that is usually fairly easy to resolve. Defective and/or poorly calabrated control/safety devices like Pressuretorls and Vaporstats will allow pressures to build, especially during extremely cold weather or when a set-back thermostat has been set to 4+ degree swings.

    As far as reinstalling the radiator on top of your new hardwood floors, you do need to make sure you don't compromise the pitch of the supply piping. It has to tilt slightly back towards the steam supply valve (on a one pipe system) or the return side on a two pipe system) and the radiator needs to have a slight pitch accordingly. If the supply pipe doesn't line up and you have some play in the supply pipe, and still maintain some pitch, you can try to pull it up a bit and reconnect it. If it throws the pitch off or in the wrong direction, you will have to extend the supply pipe enough to align it to the radiator spud. If you lose all your pitch or pitch it in the wrong direction, you will know it soon enough as you will get some banging/water hammer in that radiator or its supply piping
  • rrwitherspoon
    rrwitherspoon Member Posts: 104
    Thank you soo much
    Have a great Thanksgiving with your family