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Steam radiator knocks then steam valve shoots water

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I have a one pipe steam system. It is probably as old as the house (1947). About 15 minutes after the furnace turns on, the radiator in the second floor bathroom has the standard metal on metal banging sound followed by streams of intermittent water shooting out of the steam valve. The pitch appears to be o.k. Do I need to replace the valve? Do I need to pitch the radiator even more than it already is? Please help. Thanks.

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  • Michael_29
    Michael_29 Member Posts: 6
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    Steam radiator knocks then steam valve shoots water

    I have a one pipe steam system. It is probably as old as the house (1947). About 15 minutes after the furnace turns on, the radiator in the second floor bathroom has the standard metal on metal banging sound followed by streams of intermittent water shooting out of the steam valve. The pitch appears to be o.k. Do I need to replace the valve? Do I need to pitch the radiator even more than it already is? Please help. I have attached photos. Thanks.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
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    You may have

    too big of a vent on that convector. It looks like a Gorton style vent. Can you see any markings on it? Do you have vents on your steam mains in your basement?

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  • Michael_29
    Michael_29 Member Posts: 6
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    Gorton \"Vapor Equalizing Valve.\"

    I'm impressed. It's a Gorton "Vapor Equalizing Valve." I'm not sure what a steam main looks like, but I can tell you that out of eight radiators in the house, this one is the only one with this problem. I hope that helps.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
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    Do all your other

    "radiators" look like the one pictured, only bigger? Do they have the same type vent? Those type of radiators are called "convectors"

    The "steam mains" are the bigger steam pipes in your basement that supply the smaller pipes that go to your "radiators". Go to the ends of these steam mains. There should be a bigger version of a radiator vent somewhere down there. If not, one should be added.

    Then, a smaller vent can be installed on that problem convector. If the convector is over-vented, steam rushes in and as it turns back into water, it can't drain back out because more steam is still rushing in toward that big vent. The steam carries that water out and your vent spits. The steam condenses into the water in a blink of an eye, causing water hammer. The water hammer has most likely caused that vent to fail, allowing even more water and steam to escape.

    I suspect the big vent was put there because the convector didn't heat fast enough. And the convector didn't heat fast enough because there are no main vents on your steam main.

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  • Michael_29
    Michael_29 Member Posts: 6
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    Yes, there are more of the same steam vents in the house. I do not see any vents on any of the mains. Can I simply change out the problem vent for a smaller one?
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
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    Yes, but

    your system will work SOOOO much better with properly installed and sized main vents. Really, truly, it will. Then, all your convectors will get hot At The Same Time, and with smaller vents. Your vents will last much longer, as they will not be venting the mains AND the convectors, too. And your boiler will last longer. Leaking vents kill boilers slowly.

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  • Michael_29
    Michael_29 Member Posts: 6
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    Thanks for your help.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
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    You're welcome



    and please let us know how it works out.
  • Michael_29
    Michael_29 Member Posts: 6
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    I replaced the questionable steam valve on the convector. No change...it still leaks water. I accidentally found a main with a steam valve attached. Should I attempt to change this valve or is there possibly a different problem I should be addressing?

    Thanks.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
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    Do you have a picture

    of that main steam valve? Also, check the slope of the pipe running out to that problem convector from your steam main.
  • Barbarossa
    Barbarossa Member Posts: 89
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    convectors

    Nobody asked the pressuretrol setting and yes this can be a case where the vent is too fast. If the issues stop after the unit is at temp it might be proof of the above argument that condensate is being formed faster then it can counterflow out.
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