Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

steam rads: AIR VENT SIZES

ben Member Posts: 2
How do we know the size of an air vent on a rad or a main? Is the number engraved on the vent, the size? So does number 40 make sense on most of my rads? I recently replaced a broken number 12 from my main with a number 40 because it was all they had at the plumbing supply store. Is that OK?
What is the basic rule of thumb for sizing vents....mains, end of mains, and rads close and far from the boiler.
Thanks for any suggestions!


  • on the left side tool bar

    is a catagory called ''books and more''.
    in there is a video seminar called DEAD MANS STEAM SCHOOL, in this course is the proper sizing criteria for steam vents. its the only place i know to get it. its probably easier for you to purchase the course and have the workbook in hand then to figure it out here. you'll have to supply more data than you did for us to do it. hope that helps.
  • Steamhead
    Steamhead Member Posts: 16,726

    Never heard of that one- what brand was it?

    The Hoffman #40 is undoubtedly too small to properly vent a steam main. Get the video and workbook Gerry mentioned, and you'll be able to pick the vent you need.

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
This discussion has been closed.