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I now have a hole in the main line pipe...

Today I went to replace the air vent on the main line that was leaking steam. Off of the main line elbow joint heading up to the first floor was a small elbow joint leading to the vent. The small elbow was at an angle, so the vent was at an angle. It seemed like a good idea to straighten these. A little brute force and I tore the small elbow right off. Turns out, a previous owner added a vent by tapping the main line and screwing in an elbow joint. Now I have a 1/4" hole in the main line with half of the small elbow threads still in there. My questions is, do I really need a vent there? The main floor has two radiators only a few feet from this spot. Clearly there was not a vent there to begin with. Do I weld a patch over the hole and call it a day? Weld a new elbow joint on and add a vent? Tap a bigger hole in and screw in a new elbow joint?


  • Steamhead
    Steamhead Member Posts: 16,736
    How long is the main, and what pipe size?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • KC_Jones
    KC_Jones Member Posts: 5,707
    A picture is worth 1000 words. Post a couple pictures of your situation and it will be much easier to help you out. One thing I can tell you, you need main vents.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Jessie
    Jessie Member Posts: 6
    Half the threads are in my hand, half are in that hole.

    Without measuring, I'm guessing it's about a 3" pipe and 18-20'.
  • Dave0176
    Dave0176 Member Posts: 1,177
    Looks like 2" pipe. That's not an ideal spot for a main vent anyway, it should be about 15" from the end of the main run or at the drip were the dry return drips to the wet return.

    You could try to use an extractor but it look pretty corroded, how far back is your nearest union??
    DL Mechanical LLC Heating, Cooling and Plumbing 732-266-5386
    NJ Master HVACR Lic# 4630
    Specializing in Steam Heating, Serving the residents of New Jersey


    I cannot force people to spend money, I can only suggest how to spend it wisely.......
  • billtwocase
    billtwocase Member Posts: 2,385
    Looks like you may have enough surface to drill and tap a 3/8" bushing in there. Attach a magnet to the elbow so it might grab some of the shavings. Good luck
  • kcopp
    kcopp Member Posts: 4,396
    I would keep the same size hole and just re-tap it.
  • Steamhead
    Steamhead Member Posts: 16,736
    We'll need a better idea of where that vent is on your system. From the picture it looks like that's a branch line from the main that feeds the two radiators you mentioned.

    If so, is this line appreciably longer than the other branch lines?

    If not, does the main line slope down from the boiler and drain into a return line?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service