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too high steam boiler pressure

ww Member Posts: 282
i maintain the boiler..flushed awhile back...cleaned the chamber..the other day i replaced the 1.10gph 80 degree hollow with a semi solid. i put in new electrodes,filters..this is beckett AF with old american steam boiler. i fired up boiler and found steam coming out from top of sight glass..i replaced glass and washers...no more problems there...both valves open at sight glass.

the radiators heat up fine...awhile back i put in new main vents with t's and unions...2 on each side to vent out air quickly..it worked fine...

1. why is the boiler pressure on the 1 to 30 lb gauge between 5 and 10 lbs..when before it didn't seem to move at all..i didn't touch differential or adjust anything? I read all over here that the lower the pressure the better..like .5 lb.

I took a radiator vent off while the system was on..i had gloves on and the steam was under way more pressure than normal...i turned the valve off at the radiator right away. this isn't how the pressure should be.

2. there are two valves on the boiler on the same side as the glass tube..what are they for and they look like a long threaded rod on them..they are closed now..not sure if they were closed before.

I've been reading this site for awhile and enjoy it. thanks if anyone can pick up anything here. i imagine it could be a bad pressure cutoff somewhere and if so would like to see how to test that. thanks alot.


  • BobC
    BobC Member Posts: 5,401

    The valves at both ends of your sight gauge should be open so the glass can sense the boiler water level.

    Assuming the pressuretrol is set to 2 psi or less on the front and 1 on the little white dial inside your boiler pressure should only be 1.5 to 2 psi. It's likely the pigtail between the pressuretrol and the boiler is plugged. Take it apart and make sure it's clear.Then turn that pressuretrol upside down and make sure the tiny hole at the base of the brass fitting is clear.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • ww
    ww Member Posts: 282

    ok..i'll look at this tomw.i'll find out the model number of the unit and look at the adjustments.

    the two valves by site glass are open..the ones that are closed are the two next to the site glass on the boiler and don't know what those two are.
  • Mystery valves

    How about some pictures?--NBC
  • ww
    ww Member Posts: 282
    BOILER PRESSURE TOO HIGH UPDATE...FIXED..Photos and the mystery valves too..

    As directed by Bob C  I did as instructed. I had previously checked all those pipes leading to the pressuretrol and I didn't check the small hole on the bottom!

     That was clogged. I cleaned it up and all works fine now. There is a piece attached to the boiler just below the gauge that looks the size of a small ball...I think that this must so what the pigtail does or some similar usage.

    The pressure on the boiler is now below one lb. I am considering using a tee and putting a low pressure gauge just to see very accurately how much pressure there really is.

    The reading on the pressuretrol says that the left reading scale added to the right reading scale which is the differential adds up to the differential. That tells me the cut in pressure is zero. All works fine and the place heated up really fast.

    I read this column before and was instructed on how to vent out the air from the mains in the basement and used tees and unions to put two large air vents on the long and short runs.

    Thanks Bob!

  • BobC
    BobC Member Posts: 5,401

    I'm glad it's working right now, it's supposed to get cold Sunday and  Monday.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    Mystery valves

    Those two small valves behind the sight glass are try cocks used to check the water level. If you open the bottom one you should get water out, while opening the top should give you steam. This tells you that the water line is somewhere in between them in height.

    The boiler may not have originally come with the glass and the valves may have been the only method to check the water level in the boiler.
  • ww
    ww Member Posts: 282
    thanks for identification of valves

    ok..great..now i know what they are. thanks Mike.
  • Boiler pressure is way too high!

    Hello all,

    I need some help please.

    My radiator is spewing water from the valve.  It flooded the floor, and I am emptying a bucket or so every half hour from it.  When I looked at the pressure valve it reads 5lbs.  It usually reads just under 2. 

    So I turned off the water to the radiator in question, and turned down the heat by 5 degrees.  Now when I look at the valve it reads 0.  I am also smelling a little gas coming from near the boiler.

    Any help?
  • JStar
    JStar Member Posts: 2,752

    First, call a professional, or the gas company if you smell gas. Leave the boiler off until you find the source of the leak.

    Second, at the boiler, there should be a water feed valve. Make sure it is all the way closed.