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How do I loosen a stubborn Main Vent?

I want to remove my main vent to check if it’s ok and clean it if necessary. I may not have the right tools to remove it. I used a large pipe wrench and was not successful. Any advice on how to remove it?


  • Jamie HallJamie Hall Posts: 11,900Member
    That's a nice vent. It isn't big enough to be a main vent, however, so if you can get it off of there you should plan to replace it with at least a Gorton #1 or #2, depending on how long the main is.

    As to getting it off. give it a good shot of PB Blaster or something of the sort and let it sit, then another. And another... Then a good pipe wrench on the vent and another on the busing as a backup. Or, if you don't want to risk damaging the vent, a wrench on the bushing and another on the reducing fitting below it.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • BobCBobC Posts: 5,056Member
    Apply Kroil or PB blaster to both the vent and the reducer and let it sit for a day or two, apply more oil and whack the base of that vent with the handle of a large screwdriver and give the reducer a couple of whacks as well. That whack may allow the oil to penetrate down into the threads.

    Use a good size wrench and try the reducer first, if it doesn't give try a pipe on the wrench handle to give you more leverage. If that doesn't work try removing the vent only.

    The vent should come out (brass on steel) but that reducer is rusted in place (steel on steel) and could take some work to get out.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • tomsloancamptomsloancamp Posts: 45Member
    Got it off! Next problem... it’s need to be replaced... what size connection do I need? When I measured the diameter off the old MarValve Connection it measures 1/2 inch. The local heating supply didn’t stock Gorton only Vent Rite. The only size they had was #33. The connection size for that is 1/4 male. I’m confused as to what size connection?
  • ethicalpaulethicalpaul Posts: 1,360Member
    edited November 2019
    Main vents that I have seen come in 1/2 or 3/4 NPT (some are threaded for both). Go online to find a Gorton #1 or #2. The Ventrite is not big enough for a main vent IMO.

    But first report the length and diameter of your main (from boiler to this vent) and someone will tell you the right size to get.

    Also they will advise that you put a nipple (as high as your ceiling allows) on that Tee to an elbow with another nipple (about 12") pointed back toward the main with another elbow on THAT into which you will attach the vent (see bad ascii art). This helps prevent water from getting pushed/splashed into your vent by steam moving fast in the main.

    1 pipe Utica 112 in Cedar Grove, NJ, 1913 coal > oil > NG
  • acwagneracwagner Posts: 413Member
    This is a good online site for vents:
    Burnham IN5PVNI Boiler, Single Pipe with 290 EDR
    18 Ounce per Square Inch Gauge
    Time Delay Relay in Series with Thermostat
    Operating Pressure 0.3-0.5 Ounce per Square Inch

  • pecmsgpecmsg Posts: 1,056Member
    When reinstalling use Never Seize!
  • Hap_HazzardHap_Hazzard Posts: 1,956Member
    pecmsg said:

    When reinstalling use Never Seize!

    PTFE tape is better for this application.
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • ethicalpaulethicalpaul Posts: 1,360Member
    I had to edit my ascii art because the site collapses leading spaces :disappointed:

    Have another look it's better now
    1 pipe Utica 112 in Cedar Grove, NJ, 1913 coal > oil > NG
  • Hap_HazzardHap_Hazzard Posts: 1,956Member
    There should be a unicode script for pipe fittings.
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
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