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Main vents not there

Fred Harwood
Fred Harwood Member Posts: 261
get Dan's "Lost Art of Steam Heating" from this site. Coal-fired steam systems often need conversion from vacuum to vapor, and other changes. As you will see from Dan's book, modern steam boilers like fast mains venting, which should be added as needed, once you understand the parts of your system. Also consider a Vaporstat, and do the math on the radiation load and the boiler rating to see if it's closely matched. A large boiler connected to a small heating load will cycle too often, have large pressure swings, and probably bang.


  • Chris_35
    Chris_35 Member Posts: 49
    Main vents not there

    I have a one pipe steam system in my house.
    I H
    had a new boiler installed 2 years ago and its hooked up to the old piping.
    The vents on the rads hiss loudly when the boiler is on. (they are not clogged and they do not spit water or steam).
    I have checked all the piping and there are no main vents at the ends of the mains. I have read in here that there should be vents on the mains but the guys who originally installed the system (almost a 100 years ago) didn't put any on. Can I have some put on or should I just put bigger vents on the rads?
    The guys who installed my new boiler said that the hissing and banging is normal, but, then again, he also said I don't need to insulate the pipes.(which I have now done on my own)
    The original boiler was coal fired.
  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
    Defintiely put some on

    I have spoken to numerous homeowner's that have been told that hissing and banging is normal by contractors. Both these symptoms indicate something is Wrong! It sounds like your boiler may not have been piped right during installation, so it would be good to look closely at the installation manual and, if possible, post some pictures here. There are many fine steam contractors here that may be able to give you an idea what may need to be done and, may be able to do it for you.

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