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Advice for safely removing half-century-old steam-radiator air-vents - in one piece?

After poking-around online, looks like what appears to be a very simple screw-off screw-on procedure, can turn into trouble (breaking off, stripping threads etc.) - at least for those vents which have been in place for decades.

Why now? Looks like pretty much every radiator vent in an older house (one-pipe steam/cast-iron rads) is constantly open or otherwise not-right, and could use a change-out. (And maybe the visible 2nd fl bathroom fat-pipe vents, too.)

(From readings, do acknowledge the importance of the other vents in a properly balanced system, but for now not considering the mains' vents, or the heard-but-not-seen kitchen vents (fat-pipes?) completely masked by panels or cabinetry.)

Thank you for any pointers.


  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    I would consider the main vent(s). Getting it or them working correctly can fix a lot of problems.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • Also verifying the pressure to be low: under 1.5 psi, (basic function), or under 8 ounces, (economy), will often solve radiator vent problems, as long as the main venting is generous.--NBC
  • dopey27177
    dopey27177 Member Posts: 887
    I am a retirerd New Yorker
    Spent 60 years working Brooklyn and Manhattan.

    What you failed to say is the system working well.
    If it works well, good heat no banging or other funny things happening my advice do not fix what a'int broke.

    Typically the removal of a radiator vent is no problem.
    If you want to replace vent valves your tool kit should include an easy out, 1/8",1/4" pipe tap a 1/8" and 1/4" pipe tap. For your main vent Maid O mist #1 main vent 3/4x1/2" threaded.

    In most homes in Brooklyn, queens and Staten island Maid O Mist adjustable vent valve 0220 5LA model. Comes with 5 separate adjustments for each valve.

    You do not have to buy valves to test how well they work in a particular room (balancing thru air venting) and getting stuck with a used valve that you cannot exchange.

    The valves are good but the down side even at about 5 dollars each is they are made in China.

    Additionally set the boiler pressure 1/2psi on and 1 Psi off. for this you may need a vaporstat.

  • ch4man
    ch4man Member Posts: 296
    edited September 2020
    half a century? thats only a mere 50 years....1970 sheesh..
    i worry when they're older than me by quite a bit.............
  • mattmia2
    mattmia2 Member Posts: 9,622
    I pulled a galvanized water pipe out of a galvanized fitting that was from 1957 to adapt to copper a couple weeks ago
  • Jim_NY
    Jim_NY Member Posts: 46
    Thanks everyone. This is a new type of DYI for me. (Doing this now, since it'll be at least a couple of weeks until any steam-heat is needed.)

    Had a chance to check 3 radiators and 1 fat-pipe, and so far all Hoffman 40s. They looked rough but unscrewed without any real problem. None of the 4 had any indication of either tape or thread sealant. (Which may be why some - of the sorta-working ones - were all hissing constantly?) Looked closely at the threads on one radiator, and they appeared rust-colored and nicked. Perhaps I should try Teflon tape + a flexible type sealant when new ones are installed.
    responses to comments above / may be off the original radiator-vent topic:

    - Only half-a-century? Well 50 years since there was anyone in the house who could have even thought to check-on or change a vent, so they could be older . . .

    - As far as pressures, don't know what the *actual* working pressures are. The only thing I can see is the pressuretrol cut-in setting near ~0.4 kg/cm2 (the US/english scale is only labeled at top and bottom, but guess that's ~5 PSI).

    - As for the mains' vents, don't think I'd yet be comfortable working on those, as each of the two visible ones (at the very front and very back of the house piping) poke half-way into the basement ceiling. Can't imagine they've been touched, unless perhaps the last boiler installer did so. Never made any detailed observations, but as best I recall when randomly walking by, both were occasionally heard to spit or hiss - whatever that may mean for function.

    - As far as the system, the boiler itself Bryant (Dunkirk Radiator PSB41 Series?) as of last season was working to heat the house. Nothing quantified, but feel it loses more water than it should when operating (frequent fills). Only things I've done recently were change out a sight-glass last fall, and replace a thermal fuse two years ago - the chimney was checked OK. (But there was a major 3-day-in-Feb-no-heat repair about 6 years back that I'd love to find out if I'm just a skeptic, extremely ignorant of what HVAC troubleshooting/repair looks like, or if far, far more work was done and more parts changed than actually needed.)

    - As far as concepts like balance. Ouch. Over the years (coal->oil->gas) it appears 3 of 4 1st fl radiators have been removed, as was one from the 2nd fl landing at the top of the hallway stairs. And I'm told - historically - the 2nd fl (of 2 floors) front (prob furthest part) "always took and still takes forever to heat up" while 2nd fl back is hot fast. (And, of course, one resident feels too cold at the same room temperature that another feels very hot . . .)

    - Appreciate the local info, tap and MoM valve specifics. What I believe are the current mains' vents must be another brand as they are vertical "rocket" shaped. Are those $5 tap-and-drill-bit combos online good enough for DYI? (And is it 1/8" NPT 27, + an "R" bit or + a 21/64" bit or no difference in practice?)
  • BobC
    BobC Member Posts: 5,477
    Bnts are usually made of Brass so they should sieze to cast iron radiators but some may be a bit of a chore. If they don't budge when trying to loosen try tightening then just a bit. I find slow steady application of force is best.

    Main vents can be a bit tougher but a good 14" wrench usually does it with occasional help from a 2 ft cheater. Do use some teflon tape (several wraps) on any vets you replace, it will help seal any nicks and make future replacements very easy.
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • mattmia2
    mattmia2 Member Posts: 9,622
    When you unscrew the vents, cup the whole thing in your hand so you are supporting most of the surface and pull/push in the direction the elbow of the vent turns, so you are as much as possible just placing force to rotate the threads, not tilt them in or out or push them sideways which may tend to bind them and might break them in an extreme case.

    The pressure should be set much lower.