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Malfunctioning Main Vent in Steam System

Hi all,

First post here, but I’ve found this site very helpful. Thank you to all the experts who help the wandering lost like me.

I noticed the vent at the end of the 50-foot main in my single family home is not closing. I can’t say I actually see the steam coming out or hear gurgling, but if I hold my hand over it there is very hot air blowing out. It was recently installed too...

The radiators that it feeds don’t generally get a lot of heat, so I’m hoping this could be a good fix.

The challenge is that this vent is in my otherwise unheated garage and only a few inches below the garage ceiling. If necessary, I can remove a section of the ceiling in this area to allow for a higher vent placement between the floor joists.

So, should I replace? Try to fix? I’ve read a little about Gorton vents—they seem to have a big impact.

Thanks for the advice,


  • BronxNYSteam
    BronxNYSteam Member Posts: 4
    Oops, here’s a pic.
  • Fred
    Fred Member Posts: 8,541
    That vent is seriously undersized. A Gorton #2 or a Barnes and Jones Big Mouth would be more appropriate. My only concern is if the garage is unheated (I see the steam pipes are insulated and they should be) I'm not sure if the vent is faulty or if the frigid garage temp prevents the vent from staying shut like it should.
  • Jamie Hall
    Jamie Hall Member Posts: 21,541
    @Fred does have a point, but I think that if you mount the new vent -- I'd use the Gorton #2 -- where that existing vent is the heat conducted through the steam pipe should be adequate to keep it functioning properly.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    STEAM DOCTOR Member Posts: 1,787
    Not really the proper location for that vents. Vent is close enough to the waterline to allow water into the vent and prevent it from closing
  • rjp8292
    rjp8292 Member Posts: 10
    I have a one pipe steam system. One main pitched away from boiler that loops into a return back to the boiler. My question is why is there no main vent? Can I put one in if I drill and tap the 2"elbow at the end of the main or do I have to mess with the 100 year old pipes and install a union?
  • BronxNYSteam
    BronxNYSteam Member Posts: 4
    Thanks for the advice. How do I get around the low ceiling problem? Should I open up a section of the ceiling so that I can extend the Gorton 2 up in between the floor joists? Should I worry about all that air blowing into that cavity (do I need to protect the joists in some way?)
    STEAM DOCTOR Member Posts: 1,787
    I think that you are best off figuring out a way to have vent come off top of pipe, not side. Either drill and tap or replace elbow with heel T.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,575
    Main vents can be mounted on the vertical drop of the return, if you have enough height, and low pressure. Steam head posted a picture of that sort of installation, but I can’t find it now.—NBC