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Can you tell if a quiet (mains) air vent is working - without removal?

Jim_NY
Jim_NY Member Posts: 46
edited October 2021 in Strictly Steam
Seen here mention of the self-explanatory "blow test" - curious if there is any common way to check "quiet" vents without removing them?
Tried a piece of tissue-paper, but it moves from random currents and heated ambient air alone.
Looking at the rocket-shaped vents installed here, one thing that comes to mind is fitting an air-squeezed-out, limp, light plastic/elastic item over the vent, and seeing if it inflates a bit - but not sure the pressure of the driven-out air would be enough to produce a visible difference.
If it's relevant, photos are attached - one is a Flair No 59 (Flair Manufacturing Hauppauge LI NY - Korea - straight connection NPT 3/4x1/2) and the other I can't read from a distance.
And yes, from hanging around here, do see the installed terminal positioning of the vents both vertically and horizontally is, ahem, not ideal.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    Those vents are probably working, but I would imagine -- unless your mains are very short -- that they are too small. But that's not the question.

    Oddly it is very difficult to tell if a main vent is working. I'd not thought of your idea of a limp something over the vent, though -- it would probably work.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,516
    Maybe a zip lock plastic bag Never tried it though.

    Best way would be start with a cold boiler (or at least no steam) and run it until the supply steam pipe leaving the boiler get's hot so you can't touch it. Then start timing and see how long it takes to get steam at the vent location. Ideally you want both vents to get hot at the same time.

  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    For what little it's worth, I have, now and then, tried to figure out in some way if both of Cedric's main vents (they are on a tree) are working during a normal start up -- one Hoffman 75 and one Gorton #2. Never been able to convince myself that they are... but obviously, since the system works as intended, they are...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Jim_NY
    Jim_NY Member Posts: 46
    edited November 2021
    Thanks to all for the comments.
    Yes seems hard to tell whether majority of air venting is done through mains vents, radiator vents, fat-pipe vents or some combination.
    Tried what in another realm is called a quick and dirty experiment.
    Methods: Cold system. Front-of-house vent covered by small plastic sandwich bag, tightly wrapped electrical tape at base, with just a bit of air in the bag. Started boiler. Observed front-of-house vent.
    Result: Pipes before the terminal vent, and the return pipe below the vent got too-hot-to-touch before the vent itself. Didn't see any change in the amount of air in the bag.
    Conclusion: none. No positive or negative controls, only one try.
    Impression: If it's working, it's slow and noiseless.
    -
    > they are too small
    Very possibly. Would guess the mains extend probably 45 ft to the front and 30 ft to the back from the boiler.
    Could not find cfm or other stats on the Flair website. Although the company seems to solicit business by email-request (NOS?), steam vent product info seems mostly scanned images of 1970s-looking brochures.
  • ChrisJ
    ChrisJ Member Posts: 15,664
    I've put my ears by mine as the boiler starts steaming and I can hear them vent.
    It's not loud, but it's certainly a sound even at 0.25" WC (0.009 PSI).

    Wait until it's quiet in the house to do the test.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • dopey27177
    dopey27177 Member Posts: 887
    Try the tissue paper again. But use a rubber band to hold the paper tight against the vent valve opening, if the vent works the tissue paper would wind up having a hole in it from the moisture and slight air pressure.

    Jake
  • JUGHNE
    JUGHNE Member Posts: 11,060
    The flame from a grill lighter or candle would move if air passing.

    For rad vents, I moisten the inside of my wrist to feel the air moving.
    (I don't want to say I simply lick the wrist....but maybe)
    Just like checking the temp on a baby bottle.
    Do this before anything is hot.
  • Jim_NY
    Jim_NY Member Posts: 46
    edited November 2021
    Thanks for the additional comments.
    Re-tried ear, finger, and tissue tests as suggested (at the reachable front air vent). Heard/felt nothing, and tissue never got damp or torn. Also noted it took 10 minutes more after connected/nearby piping was hot, for the air vents themselves to get hot (direct touch for front, non-contact thermometer for rear). Don't know if that is what's expected, but it kind of felt as if they slowly heated by metal-metal conduction from the pipes, rather than from steam.

    Also saw that the outsides of the main pipes from boiler to front (and from boiler to rear) first got hot in order of distance from the boiler. Pipes routed up from mains got hot in same order, and again although all nearby piping was hot, it took the vents additional time to heat up.
  • delcrossv
    delcrossv Member Posts: 742
    10 minutes seems awfully long. How long are the mains?
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • Jim_NY
    Jim_NY Member Posts: 46
    edited November 2021
    Probably 45 ft to the front and 30 ft to the back from the boiler.
    And to be clear, the metallic vents only felt hot ~10 minutes after the previous ~10 min for the adjacent main pipes to heat up.
  • delcrossv
    delcrossv Member Posts: 742
    edited November 2021
    If I had to guess, they're probably toasted or really slow. 45 feet of 2.5" pipe is a little over 1.5 cubic feet. So a Hoffman 75 should vent that in 3 minutes. (.5 cfm off the table) . The only numbers I could find for a Flair were for a 51 rad vent at 0.1 cfm. (really slow)

    Is your question arising because some radiators aren't heating quickly?


    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • mattmia2
    mattmia2 Member Posts: 9,627
    delcrossv said:

    45 feet of 2.5" pipe is a little over 1.5 cubic feet. So a Hoffman 75 should vent that in 3 minutes. (.5 cfm off the table) .

    That isn't entirely correct because it also needs to heat the pipe for steam to flow in it. Some of the steam entering the main progresses along the pipe to push the air out but some of it condenses as it heats the pipe to steam temp.

    delcrossv
  • JohnNY
    JohnNY Member Posts: 3,229
    I haven't read all the replies here but I use one of those long BBQ lighters to check air vents. I put the flame up to the opening and watch the flame as it gets pushed and pulled away from the vent. Works like a charm. A match works too but less well. I use a small telescoping inspection mirror to check for vents I suspect are passing steam.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
    Classes
    mattmia2
  • KC_Jones
    KC_Jones Member Posts: 5,736
    delcrossv said:

    If I had to guess, they're probably toasted or really slow. 45 feet of 2.5" pipe is a little over 1.5 cubic feet. So a Hoffman 75 should vent that in 3 minutes. (.5 cfm off the table) . The only numbers I could find for a Flair were for a 51 rad vent at 0.1 cfm. (really slow)

    Is your question arising because some radiators aren't heating quickly?


    I don't see anyone venting a 45' long 2.5" main in 3 minutes with a single Hoffman 75. That is at 1 ounce of pressure, you are starting at 0 and can't get to 1 ounce unless you have insufficient venting. Pressure in a steam system isn't really pressure in the classic sense, reading pressure is back pressure, in other words it's "generated" from the end, not the beginning.

    I don't know how long it would take, but to get to 1 ounce of pressure would probably take more than 3 minutes, in the meantime the steam isn't moving very much. This is as Dan states low pressure moves faster, because to make pressure requires you to stop or significantly slow down the steam. The lowest pressure is zero.

    To be clear I have a system, as do others on this board that don't ever see 1 ounce of pressure. The venting chart is a guide for what is faster and what is slower, but taking those numbers and actually applying them to the system, IMHO doesn't work. You will always need more, some will disagree with me and that's fine.

    On a hot start my system vents a 32' 2" main in max 3 minutes from boiler firing to end of main hot. That's verified with a temp sensor and the PLC control. I have a big mouth vent on that main. I used to have 3 Gorton #1 vents which gave me double the capacity of a single Hoffman 75 and similar times to the current big mouth. The theory you are presenting is venting twice what I do in the same time with half the venting. I don't see that happening.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    ethicalpaul
  • delcrossv
    delcrossv Member Posts: 742
    edited November 2021
    @KC_Jones Aah! The numbers! They Lie! :D

    I just presented the volume/ cfm as a best case scenario,
    I'm in agreement with you, but it seems 10 minutes is a pretty long time for a 45' main to get hot if adequately vented. FWIW, my "fast" main (about 40' )takes about 5 minutes from start of steaming to get hot with a 75, while to get my 100+' "slow" main to equal that takes 3 Big Mouths. (same as an open 3/4 pipe)
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • ChrisJ
    ChrisJ Member Posts: 15,664
    I ended up with five Gorton 1's on a 32' long 2" main.

    4 wasn't quite enough at times in my opinion.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Jim_NY
    Jim_NY Member Posts: 46
    edited November 2021
    > If I had to guess, they're probably toasted or really slow.
    Untouched for decades and not sure who installed them, so quite possible.
    > flame from a grill lighter or candle [or] > BBQ lighter . . . watch the flame as it gets pushed and pulled away from the vent.
    Sounds like a very sensitive useful test. Unfortunately these vents are practically touching ceiling (front) or an exposed beam (rear), and both are inches from somewhat drafty basement windows.

    Note to readers from OP, we're moving away from the original generic question so the following may be OT to some:
    > Is your question arising because some radiators aren't heating quickly?
    Really have no basis for comparison as to what's considered slow.
    From a cold start, the front first floor radiator takes about 20 min to start to heat up at the end nearest the single pipe, and a fair while longer (never timed) for the air-vent side to feel as hot. The front of the house 2nd (top) floor (1st fl UK-style) has always been described as slow-to-heat.

    Reason is just looking (mostly here) for ways to perhaps get things a little better with the steam system, a little at a time, at low expense. (Also without breaking anything - being a non-plumber, non-pipe-fitter, non-HVAC, non-super, etc.)

    To that end switched out all the apparently blocked or steam-hissing radiator air vents last heating-season. Now wondering about the mains' air-vents. Had also insulated bare pipes on the visible long basement runs (and considering putting just-in-case wraps over any it-can't-be-asbestos old-painted-over existing pipe insulation). At the boiler, lowered seemingly-high Pressuretrol settings (although no low-pressure gauge to see the actual operating numbers). Even changed out the sight gauge glass and gaskets/washers ($20 vs $150-$350 pro charges in past).
    delcrossv
  • delcrossv
    delcrossv Member Posts: 742
    edited November 2021
    Based on your comments above, going with faster main venting wouldn't hurt. I had my recent sojourn with main venting here:

    https://forum.heatinghelp.com/discussion/185113/fast-return-slow-return

    It's been pointed out to me that main and radiator venting aren't isolated, but tied together as part of the system.
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    Main venting... ah yes. First, it's almost impossible to overvent a main. It is, however, quite possible to spend way too much money doing it.

    I don't recall seeing -- I just skimmed most of the above -- but is the main insulated? That makes a big difference. Whether it is or is not, however, 10 minutes strikes me as too slow, if that is measured from when the steam actually gets to the header, not from when the boiler first fires. Also, the fact that the pipe leading to the vents does not get steam hot as fast as the adjacent main is telling.

    I think new vents are in order here...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Jim_NY
    Jim_NY Member Posts: 46
    > going with faster main venting wouldn't hurt.
    > however, quite possible to spend way too much money doing it.
    > is the main insulated?


    Certainly have noted comments on and recommendations for various ones in other threads. Probably would consider pricing/value of new mains' vents, since trying to keep expense low.

    More length of the main/pipes are insulated than before, but for various reasons not yet end-to-end insulated. Have to say the house does heat comfortably-enough as is, but will likely try to change out the more accessible (and slower) front one - probably right before a plumber is to visit for other reasons - just-in-case.

    Realize would benefit more, and more quickly, from a steam pro's inspection and evaluation of the entire system as it is, but right now can't afford such a consult + the cost of any recommended modifications.

    Thanks again to all for your experience and expertise.
  • delcrossv
    delcrossv Member Posts: 742
    edited November 2021
    FWIW, 2 new Hoffman 75's will set you back about $180 and half an hour. Don't forget teflon tape on the threads.

    You may be surprised how big a difference working main venting makes. :)
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • Jim_NY
    Jim_NY Member Posts: 46
    > Hoffman 75's . . . You may be surprised how big a difference working main venting makes.
    A nice surprise with heating really would be different . . .
    Just poked around online after measuring the actual space. Looks like because of the tight fit, only the vertically shorter ones, perhaps like like Hoffman 4A, Gorton 1, Vent-Rite 35, might fit - at least without some demo . . .
  • ChrisJ
    ChrisJ Member Posts: 15,664
    Jim_NY said:
    > Hoffman 75's . . . You may be surprised how big a difference working main venting makes. A nice surprise with heating really would be different . . . Just poked around online after measuring the actual space. Looks like because of the tight fit, only the vertically shorter ones, perhaps like like Hoffman 4A, Gorton 1, Vent-Rite 35, might fit - at least without some demo . . .
    Use multiple Gorton 1s.

    DO NOT use Hoffman 4As, they're a sad joke as far as speed.


    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • delcrossv
    delcrossv Member Posts: 742
    Can you get in there with a street L and a nipple to take the vent to where you have more height? That'd open more options for you.
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • Jim_NY
    Jim_NY Member Posts: 46
    edited November 2021
    Thanks for the suggestions, and warning against the 4a.
    I have appreciated from afar the many well-done air vent "antlers" posted, and from hanging around here do realize that a vent ideally should be both horizontally away from the terminal down-bend/return, and vertically above the main/return pipe.
    But the current Flair practically touches the ceiling (maybe 3/16" gap), and clearance from the horizontal pipe to the ceiling is maybe max 4 1/2". So in the front of the house, without opening up an aged (plaster/lath?) ceiling, would just hope any single new working vent which fits (like the Gorton 1) might help some.
    Although the lack of usable height is identical in the rear of the house, something as suggested could be possible, as a section of ceiling not too far away is already lost, exposing a space between joists.
  • delcrossv
    delcrossv Member Posts: 742
    edited November 2021
    Jim_NY said:

    Thanks for the suggestions, and warning against the 4a.
    .....
    But the current Flair practically touches the ceiling (maybe 3/16" gap), and clearance from the horizontal pipe to the ceiling is maybe max 4 1/2". So in the front of the house, without opening up an aged (plaster/lath?) ceiling, would just hope any single new working vent which fits (like the Gorton 1) might help some.
    Although the lack of usable height is identical in the rear of the house, something as suggested could be possible, as a section of ceiling not too far away is already lost, exposing a space between joists.

    Hmm. 4 1/2" ? Note the union goes into the pipe and the vent goes on after so that stub height is subtracted

    Barnes and Jones Big Mouth.

    Dimensions
    Model.........Size....................A............ B............. C..............D............ E ..........Wt. #
    BJ-BM.......1/2” & 3/4”.....3-3/16”......1-1/8”......2-1/2”....3-1/16”...4-1/2”......2



    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • Jim_NY
    Jim_NY Member Posts: 46
    edited November 2021
    delcrossv said:

    4 1/2" ? Barnes and Jones Big Mouth.

    Thanks! That's a great name and a nice fit.
    Looked for comments here and saw some saying the Big Mouth may not handle water well.
    Would it be a problem? It seems to me that the mains are pitched down, and the turn-down/return is right where the vent is (photo below).
    (The angle of the photo makes it look like pitched up. Blocked out extraneous pipes.)
  • delcrossv
    delcrossv Member Posts: 742
    Mine handle the occasional spit of condensate. No vent will handle a lot of water for long.


    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • ChrisJ
    ChrisJ Member Posts: 15,664
    The big mouth is made from a radiator trap so it'll handle water fine.

    It's trying to keep it from spitting out that's the issue.  You can screw a short length of pipe in it's "exhaust" to try and trap and drain back small amounts as well.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Jim_NY
    Jim_NY Member Posts: 46
    Thanks for the info. Doesn't sound like a major issue.