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Steam boiler overfills and leaks water

Weil McWeil steam boiler. The water level does not appear to remain at a constant level. I always fill it up 1/2,  low water level light turns off. I come the next day - everything is ok, I come the day after and see water on the floor next to steam release valve. Water level gauge sometimes shows 3/4. I don't have an auto feeder, how does it overfill? Where do I look? 


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    Sounds like something is wrong. Is it possible that the pressure gauge and the pressure control are not connected to the actual steam pressure because the pressure pigtail is blocked? that would account for the pressure getting high enough to blow the relief valve. But I would think there would be a lot of noise involved

    Pictures of the boiler piping from far enough away to see from floor to ceiling
    Then close up of the pressure control, the gauge, and the return pipe "Hartford Loop" area. They would be the odd piping design near the bottom of the boiler where the water returns to the boiler

    Also a picture of a radiator or two showing the air vent or traps if any.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    If you have water on the floor near the pressure relief valve, something is seriously wrong. The boiler should operate on a maximum pressure of 2 psi. The relief valve shouldn't open until 15 psi.

    So the first thing to do is to find out if the pressure control on the boiler is operating as it should. Is there a usable low pressure gauge? Probably not... take off the pigtail connection to the pressure control and make sure it is thoroughly clean and clear. Likewise the opening to the boiler. Add a low pressure gauge -- say 0 to 5 psi-- onto it and reattach the pressure control. Set the pressure control to cutout at 2 psi for the moment (be sure you set it correctly; different types are set differently). Fire the boiler and make sure it cuts out at 2 psi, assuming that it does come up to that pressure (it may not).

    Now on the water. Water isn't magic. So somewhere there is a pipe or pipes connecting your water supply to the boiler, and the trick is to find out which one is supplying the additional -- and unwanted -- water. It could be the normal feed, with a valve which is leaking. If there is a domestic hot water coil, it could well be that.

    I'd replace the pressure relief valve while I was at it -- if it has been opening, it may not reseat properly.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
    Sounds like you have a leaky valve on the fill line. What kind of valve is it, and are you filling from a cold water or hot water source?
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • Big Ed_4
    Big Ed_4 Member Posts: 2,785
    Fill valve or how water coil . Normally we cut the pipe after the fill valve to see if any bypass and add a coupling after ... Hot water coil , does the boiler also supply hot water ?

    There was an error rendering this rich post.

  • pecmsg
    pecmsg Member Posts: 4,861
    if that pressure relief opens because of high pressure you’ll hear it in the house. It’s loud. 

    EBEBRATT-Ed Member Posts: 15,543

    Do you have an indirect hot water tank or a tankless heater coil installed on that boiler?