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What main vent is this

danmasri Member Posts: 11
I find the main vent but not sure the model. Anyone can identify it?


  • Jamie Hall
    Jamie Hall Member Posts: 22,100
    That's one of the smaller Hoffman vents -- there should be a number on it somewhere. It is probably not big enough for a modern system...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 16,454
    Looks like a Hoffman #4A or #16. Very small vent. Where is it installed on your system?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • dopey27177
    dopey27177 Member Posts: 887
    It resembles a Hoffman #4 quick vent valve, Possibly equal to the Hoffman 75 A, it has a .375 port. This vent valve is designed for small steam systems and as a replacement vent valve is very expensive.

    Gorton or Maidomist is far more economical.