Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

pressuretrol cut in ?

hi all ,new here.
I ask, 2 story house/single pipe steam, what scenario would explain why an additive pressuretrol would be set at 2psi cut in ? [pa404A].
I havent looked at the differential wheel yet, though , on that 7 degree low night on christmas eve, it was cutting out at 3 1/2 lbs on the gage trying to satisfy the stat.


    EBEBRATT-Ed Member Posts: 15,849
    Sounds like you need more venting. Check the main steal lines in your basement for air vents and post pictures. Steam works best with a cut off of 2 psi maximum and cut in at 1/4-1/2psi.

    If you building pressure you venting is inadequate, boiler could be oversized or the pigtail connecting the pressure control to the boiler and the associated piping needs cleaning and the pressure control needs adjusting.
  • Jamie Hall
    Jamie Hall Member Posts: 23,675
    There is no benefit at all to a cutin pressure set that high. The system should cut out at less than 2 psi, and the cutin should be set as low as it can go without messing up the pressuretrol (typically a shade above 0.5 psi).

    All the higher pressure does is waste fuel and overstress the vents and make steam leaks worse.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • bushka
    bushka Member Posts: 3
    The 30psi gage dial starts at 2 psi. IT never ever moves.
    On that one day it was freakish 7f @4am [n.j.] with the stat set on 70f.
    The dial needle was wiggling between 2 1/2 -3 iirc.
    The start to finish cycling was 4 times an hour ,and very tiny amount of vent spit on first floor rads. [cut in out 10 minutes and a 5min rest.]
    The gage glass water was set a little low for the lwco,so after a cut out, the warning light would blink/reset.
    It would do a slow bounce 1/2" in operation.
    So I cut the stat down to 68f and everything calmed down.
    That morning I drained out the boiler and refilled [full blowdown?] some different knocks sounds in the wall pipes, but way less than what it was LoL. [cut in out 8 minutes/30min rest]
    3 weeks later ,I drain half bucket till fairly clear "semi" blowdown. [cut in out 8min /15min rest.
    As its been fairly mild winter, 40f @ 4am,the second floor rads ,farthest from boiler ,only heat up
    halfway across now, they have gorton 6s i put in 15 year ago. And they breathe so that air is getting vented, and the riser pipes are hot
    And the plumber that installed the boiler has got gorton 1s at the ends of both mains going up.
    He serviced 2019 and replaced pigtail maybe 2016,tho that old one wasnt clogged.

    The thing is he had it 2psi on the main scale for some reason,maybe it was pipe noises?
  • bushka
    bushka Member Posts: 3
    edited January 2023
    I just lowered the cut in only , to maybe 1 psi ,
    only 2 fins on the 2nd floor rads get hot ,and some other knocking noises i didnt care for.
    all the rads are pitched back 1/4 and 1/2 shims.
    Put it back to 2psi,and halfway across again.

    Did he raise the pressure to get the farthest rads to heat up all the way?
    Its seems inconclusive right now, its been fairly mild winter, the stat is satisfied holding 70F.
  • Waher
    Waher Member Posts: 258
    edited January 2023
    Someone increased the pressure attempting to improperly solve a problem created by insufficient venting.

    Check to make sure all the radiator valves are fully open. Use a spirit level on top of the radiators to verify they are pitched to drain.
  • exqheat
    exqheat Member Posts: 188
    ? Where is the thermostat? Near the end of the system? Where the non warm rads are.
    Are the radiator valves open all the way? Set pressuretrol for 1 lb of rise from 1/2/lb. You should be heating with ounces. Indoor reset control will minimize pressure needed.
    You may want to check pipe inclines. a belly will create a steam block, and banging.
    John Cockerill Exquisite Heat www.exqheat.com Precisions boiler control from indoor reset.