Steam Radiator Spitting

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      First floor radiator keeps spitting. It isn’t leaking – water is spewing through air valve. Just replaced it, which seems to have improved it, but not solved it. An cellar examination reveals that it is at the end of a straight shot from the boiler, with 2″ pipes reduced to 1″ about five feet from valve. Other radiators on second a third floor don’t have smae problem, but they are higher up and there is a 90 degree branch where their pipe branches off (and even so they are markedly hotter than front risers). Thoughts? Wisdom? Sarcastic coments?

      7 Replies

      1. I agree with 3:17. I had the same problem, my plumber said the water level in boiler was too high so instead of steam filling the risers I was getting water in the risers. He adjusted the autofeed water supply and it has never happened again.

      2. Is the boiler flooded?

        The water level in the gauge glass should be about halfway up. If the gauge glass is completely filled, your boiler’s flooded, which would spit water out of the lowest radiator air vent.

        (http://www.heatinghelp.com/ is a very handy site — not affiliated.)

      3. Check the pitch of the radiator (so that any condensed water drains back down into the pipe when cool). With settlement of the house the pitch could be wrong and water isn’t draining properly before the steam hits the radiator. If not, the wood in the above post might do the trick. Also check the valve that you just bought: the opening might be too big – the valves with a larger vent should go on higher floors, smaller vents on lower floors.

      4. Check the pitch of the radiator (so that any condensed water drains back down into the pipe when cool). With settlement of the house the pitch could be wrong and water isn’t draining properly before the steam hits the radiator. If not, the wood in the above post might do the trick. Also check the valve that you just bought: the opening might be too big – the valves with a larger vent should go on higher floors, smaller vents on lower floors.

      5. I bought an expensive new “adjustable opening” air valve made by Heat Timer ($25) that stopped a similar problem. I also put a piece of wood under the radiator legs at the end opposite the connection to make a better downward pitch.

        Remember to wrap plumbers tape a few times clockwise around the air valve threads before installing it to prevent leaks.

      6. If you’re looking for someone to help solve the problem, I recommend Joe at AAL Boiler Service. He’s been in the business for decades, and knows radiators and boilers inside out. He solved a tough problem in our place in a couple of hours. His phone number is (718) 851-6500.