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Radiators spitting water immediately after insulating pipes in basement

My daughter has single-pipe steam heat with natural gas and 5 radiators. It's a second floor condo in a triple-decker in Boston with its own heating system. Yesterday I insulated the steam pipes in the basement with 1/2 inch fiberglass. I did nothing else.

This morning she found two radiators spitting water from the vents. This has never happened before and the other three radiators seem OK.

Both radiators are on the same riser and about 9 feet apart. I can blow air through the vents. The valves where the pipe enters the radiators are completely open. The radiators are level or slightly sloped down to the inlet. The horizontal run in the basement to the riser has what looks like a correct slope.

Any idea what I can do to fix this?


  • gypsydoctor
    gypsydoctor Member Posts: 5
    I seem to have found the answer: a leak at the inlet valve

    I was assuming that the "spitting" was coming from the vents. It was coming from a loose connection between one radiator and the inlet valve. I had to tighten it about 1/2 turn.

    The good news is this: adding the insulation appears to be sending a lot more steam upstairs--enough more to bring out this leak!
  • Steve_175
    Steve_175 Member Posts: 234
    Main vents

    Have you determined if the main vents are working and/or of sufficient size? Also was her boiler ever skimmed?
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