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One-pipe steam radiator spitting water + water hammer

dare Member Posts: 3
I've been having problems with my one-pipe steam radiator system for a few months now: loud water hammering noises (clanging and banging) + spitting water out of the vent valve. Some details:

- top floor (7th floor) apartment in old Manhattan
- one-pipe steam to convector radiator (photo here: http://i.imgur.com/lJroYIi.jpg aluminum foil only added to protect against water splash and corrosion)
- original Hoffman No. 43 vent valve failed (stuck open, venting steam) last year and replaced with new Hoffman No. 43. Second Hoffman No. 43 failed one year later (again, stuck open venting steam) and replaced with Gorton No. C vent valve. Installed with teflon tape.
- my building manager says I'm the only tenant with these problems... I share walls with 2 other units and haven't heard hammering from them.

The radiator appears to be pitched correctly, with no obvious leaks (from vent valve or supply valve), and the supply valve is fully open.

I've browsed through a few previous posts (e.g. http://forum.heatinghelp.com/discussion/153138/radiator-wont-stop-spitting-water#latest ) but I don't have access to my apartment boiler room.

(1) What can I do myself to fix the water hammer + spitting problems? Try new (smaller? new brand?) vent valve?

(2) If not, what specific directions or questions can I ask my building manager (he's historically been terrible with building maintenance issues according to 4 other residents).

Thanks all!


  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    I find it hard to believe that only this one radiator is misbehaving, as it sounds like a system-wide problem. No doubt, lack of adequate main venting, and overpressure are to blame.
    Check to make sure that your inlet valve on the convector is fully open, and not half closed.
    It would be nice to put a good low pressure gauge on your vent and verify the pressure. A couple of Jacksons spent on a gauge would be well worth the money!
    Are you an owner, or renter?--NBC
  • Fred
    Fred Member Posts: 8,542
    Even though the convector may be pitched correctly, it sounds like a horizontal steam pipe that feeds that convector may be pitched in the wrong direction causing water to pool in that area. Has anything been done to the piping that might have caused that pipe to lose its pitch back towards the vertical steam supply pipe? If you can raise the supply end of the convector and then repitch the vent end so that everything heads back down the vertical pipe, that will probably resolve the problem.
    If this is a system wide problem, it is very possible the system pressure is running too high and that needs to be resolved at the boiler, by the building Maintenance staff.
  • dare
    dare Member Posts: 3
    edited April 2015
    @nicholas bonham-carter : I'm a renter. Yes, inlet valve fully open on the convector/radiator. I'll ask the building manager to check the main venting (near the boiler, I'm guessing?) and boiler pressure (<2 psi on the pressuretrol?)

    @Fred I'm guessing the horizontal steam pipe is hidden under my floorboards? No recent renovation work has been done in over 2 years, so I doubt that pipe has changed it pitch/angle recently. I will try gently lifting and re-angling the whole convector.

    Thanks guys.