Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Reconfiguring Main Vent

Hello,

I have a one pipe steam system with one main vent right at the end of the main. I replaced it with a Big Mouth a year or two ago and it works pretty well but its obvious its seeing some water and I know this configuration is bad for the vents due to water hammer and other things. I want to redo this with an antler or something similar but I am unsure how to do that with such little room between the vent and the floor above. Any advice?




Thanks


Comments

  • Jamie HallJamie Hall Member Posts: 14,715
    Can you come out of the top of the T with a close nipple and a 90 to run your antler pipe parallel to the steam main, then come up out of that with as many Ts and one elbow as needed for however many vents you need? Be sure that the antler pipe is sloped to drain back, though -- last thing you want is for it to trap condensate.
    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
  • Kafox15Kafox15 Member Posts: 52

    Can you come out of the top of the T with a close nipple and a 90 to run your antler pipe parallel to the steam main, then come up out of that with as many Ts and one elbow as needed for however many vents you need? Be sure that the antler pipe is sloped to drain back, though -- last thing you want is for it to trap condensate.

    There is a floor joist in the way if I go parallel to the main. If I go perpendicular, there is no joist but the vent is currently very close to the floor above so I can't add much if any height.
  • JUGHNEJUGHNE Member Posts: 7,853
    If you remove the large nipple riser (2"?), then a reducer to 3/4", short nipple, 90, long nipple to get you into the joist space, (parallel to the main for the drain slope) another 90 and then riser high as possible for the vent.
  • Kafox15Kafox15 Member Posts: 52
    JUGHNE said:

    If you remove the large nipple riser (2"?), then a reducer to 3/4", short nipple, 90, long nipple to get you into the joist space, (parallel to the main for the drain slope) another 90 and then riser high as possible for the vent.

    Tips for removing the riser? I'm thinking its been there for 100+ years so was hoping to avoid removing it.
  • Jamie HallJamie Hall Member Posts: 14,715
    JUGHNE said:

    If you remove the large nipple riser (2"?), then a reducer to 3/4", short nipple, 90, long nipple to get you into the joist space, (parallel to the main for the drain slope) another 90 and then riser high as possible for the vent.

    Exactly what I meant, as well.
    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
  • JUGHNEJUGHNE Member Posts: 7,853
    1. Multiple applications of PB Blaster or such....WD 40 will not do much.
    Two large pipe wrenches with cheater pipes.
    Tapping on the tee between sprays.

    2. Then maybe heat on the tee.

    3. That looks to be a cast iron tee, if you have a union below the tee you could crack the tee off and replace it. Holding a 5-10 lb sledge on one side and wrack the other side with a 2 lb pound sledge.

    4. Or maybe call a pro for doing the above.
  • Kafox15Kafox15 Member Posts: 52
    Sorry for the delay. Got sidetracked with other projects.

    I think its going to be next to impossible for me to get that riser off but I did have another idea.

    There is a tapping on the main vent approx 9 ft away from the end of the main where the current vent is. I think I would have better luck getting the plug out of this tapping and would have significantly more room to work.

    My question being, is there any reason the vent has to be at the very end of the main or could I add an antler with a main vent at this tapping 9 ft away?

    This is the tapping. I would have to remove the drywall on the ceiling which would give me ample room for an antler.


    View from the end of the main towards the additional tapping (where the fiberglass is sticking out)


  • Jamie HallJamie Hall Member Posts: 14,715
    Well, it would be better nearer the end of the main -- but it will certainly work there. You might want a slightly faster vent on the radiator at the end of the main to compensate -- but do that after you add the one at that tapping.
    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
    Kafox15
  • acwagneracwagner Member Posts: 502
    edited January 1
    Is there a radiator take off after the plug? If not, then that will be a good spot. The main vents can be anywhere after the last radiator take off.
    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

    Kafox15
  • Kafox15Kafox15 Member Posts: 52
    Thank you both. No take offs after the plug, so I think I'll spend some time trying to work the plug free and go from there. All my rads have adjustable vent-rites so I can play with that after if needed.
  • Kafox15Kafox15 Member Posts: 52
    Alright - spent too many hours the last couple of days trying to get that plug out with no luck. Tried multiple applications of PB Blaster, heating with a torch, tapping with a hammer, 24 in pipe wrench and every combination thereof. At this point and for the sake of my back, I've given up on that idea.

    Potential third idea would be to remove the big mouth and add a street elbow in its place, then add a short nipple and a regular 90 and attach the big mouth there. I have about 5" of space between the big mouth and the joist so it would give me some offset from the end of the main. Not ideal, but its got to be better than how it is now, right?

    As far as required venting, I have about 60 ft of 2" main. I started to look through this guide but quickly became confused. Is there and easier to follow guide for calculating required main venting?
    https://heatinghelp.com/assets/documents/Balancing-Steam-Systems-Using-a-Vent-Capacity-Chart-1.pdf




  • neilcneilc Member Posts: 1,086
    you could turn 90 and run the length of the joist bay,
    real question is , is there enough height to the subfloor then ?
    what about trying to unscrew the 1 1/2 from the main?
    2 pipe wrenches with 3 foot helper extentions
  • Kafox15Kafox15 Member Posts: 52
    If I turn 90, wouldn't that affect the pitch of the antler? Yes, height will be a limiting factor that I would have to take into account.

    I did try to remove that riser from the main with the same methods (pb blaster, heat, tapping, 24" pipe wrenches) but no dice. There are also several obstructions that make it difficult to work on that pipe with such large tools.
  • neilcneilc Member Posts: 1,086
    ok,
    2 - 90s then, one to the side, the next turning up the joist bay,
    a swing joint to allow you pitch.
    you'll loose all your height in the 1st 90.
    check street ells vs 90 and a close nipple at the big box place
    Kafox15
  • acwagneracwagner Member Posts: 502
    Do two 90's together. That will allow you to make the antler pitch whatever direction or amount you want. You also put a union on the antler so you can assemble it with the vents at the bench and put it all on at once. Working up in the joist bay like doesn't give a lot of room to maneuver.

    You probably won't be able to get that riser pipe off with 24" wrenches unless you're Hercules. You likely need 3' or 4' cheater bars on the wrenches and a friend to help. I personally wouldn't want to try that during the heating system. Best to do it in the summer. With that much force sometimes things that you don't want to move start moving. Or breaking. Don't want a heating emergency in January.
    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

    Kafox15Canuckergarrettgjp
  • Kafox15Kafox15 Member Posts: 52
    Ah - two 90s makes sense! I have trouble building these types of things in my head so I will have to draw it out on paper and make sure I understand it. After the two 90s - how long should I make the antler so its far enough away from the end of the main? I will still have to account for height.

    Certainly not Hercules which is why I gave up on that idea!
  • neilcneilc Member Posts: 1,086
    4 - 6 inches the first nipple,
    then close nipp, tee, repeat
  • Kafox15Kafox15 Member Posts: 52
    Perfect - and can anyone confirm my math here?

    I have 60ft of 2" main and there is .023 cu ft in one foot of 2" main.

    60 x .023 = 1.38 cfm in my main.

    If the big mouth is 2.0 cfm then I should be good with just one big mouth, right? Or am I totally calculating this wrong?
  • acwagneracwagner Member Posts: 502
    Some would say yes and some would say no to adding another big mouth vent. It really depends on how quickly you want to vent your main, and how much of your disposal income you want to spend on 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

  • Kafox15Kafox15 Member Posts: 52
    Well....its done.

    I gave that last plan a shot but wasn't able to make it work due to height issues with the subfloor above so I went back to tackling the plug further down the main. Eventually I got fed up and decided to take the destructive route (which was admittedly a dumb risky move). Used a recip saw to cut the top off the plug and then a lot of hacksawing, heat, pb blaster, hammering and chiseling to finally pop the threads loose. Did a little damage to the threads on the T but nothing that lots of ptfe tape and thread sealant couldn't fix!

    Anyways, last night I bought all the pipe I needed and built up the antler and installed it. I have just the one big mouth for now, but I have room to add Ts and more vents if needed.

    I welcome and encourage any changes, improvements, criticisms and recommendations. Thanks again for all the help.





  • Gary SmithGary Smith Member Posts: 359
    looks good, does the antler slope to drain? can't tell from the picture.
  • Kafox15Kafox15 Member Posts: 52
    It does :)
  • SteamingatMohawkSteamingatMohawk Member Posts: 345
    Regarding adding a second Big Mouth, there is a physical limit on how fast a pipe run can vent depending on the pressure source especially at the low pressures in a residential steam system. Once that limit is reached, adding more vents accomplishes nothing beyond storing your hard earned cash in the basement.

    The length of the smaller diameter pipe in the antler could be sufficient restriction to flow making a second one not worth it. If I can find some factual proof, I'll post it. But guys like @Jamie Hall probably know it without having to calculate it or look it up.

    Removing the Big Mouth and tracing the time for the temperature increase to 212F from one end of the main to the vent connection isn't accurate, because the initial steam flow, pushing out the air, loses energy as the pipe is warmed. You could diddle around by heating the pipe run, then turning off the boiler, then once the pressure goes to 0 turning the boiler back on and measuring the time for the vent connection to get to 212F. Even then, it's a crude way to try to get a number with lots of unknown inaccuracies.

    My suggestion is to just use one Big Mouth, unless you can accurately prove it is restricting vent flow.

    In my system, with about 25 ft of 2" pipe and a 6 inch 1/2" run to a Gorton #2, when I added a second #2 nothing changed.
  • Kafox15Kafox15 Member Posts: 52
    Yea, agreed on not wanting to spend another $100 on a big mouth if its not going to improve anything. My mains heat up relatively quickly. if anything, I could add one or two smaller but much cheaper MOM #1's to just bump it up a small amount instead of uselessly doubling out with another big mouth.
  • SteamingatMohawkSteamingatMohawk Member Posts: 345
    Look at @Jamie Hall s comment in the

    Increasing Main Venting discussion for some further insight.
  • ethicalpaulethicalpaul Member Posts: 2,518
    Removing the Big Mouth and tracing the time for the temperature increase to 212F from one end of the main to the vent connection isn't accurate, because the initial steam flow, pushing out the air, loses energy as the pipe is warmed. You could diddle around by heating the pipe run, then turning off the boiler, then once the pressure goes to 0 turning the boiler back on and measuring the time for the vent connection to get to 212F. Even then, it's a crude way to try to get a number with lots of unknown inaccuracies.


    These tests are easy and accurate in my opinion. If anyone needs more than one big mouth on their main, I'll ship you mine for free.
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • SteamingatMohawkSteamingatMohawk Member Posts: 345
    In other discussions, guys have suggested doing a run with the vent installed and with the vent removed, then comparing the times. If it takes longer with the vent installed, it is restricting the flow. But be aware the starting conditions need to be as close as possible to identical, because that will affect the results.



  • Kafox15Kafox15 Member Posts: 52
    So the big mouth seems to be spitting a great deal in its new location. It certainly spit (more like dribbled) in its old location but now it is spitting out a considerable amount of water right before it closes on steam.

    Is there something about this new location that could cause it to spit more?

    I know my near boiler piping is not great and I have wet steam, but that wouldn't explain why it spits now and didn't before.

    I'm sure I introduced some oils into the system with all my PB blaster, so I skimmed today but no change in the spitting. Will probably skim a few more times.
  • Jamie HallJamie Hall Member Posts: 14,715
    edited January 10
    Kafox15 said:

    So the big mouth seems to be spitting a great deal in its new location. It certainly spit (more like dribbled) in its old location but now it is spitting out a considerable amount of water right before it closes on steam.

    Is there something about this new location that could cause it to spit more?

    I know my near boiler piping is not great and I have wet steam, but that wouldn't explain why it spits now and didn't before.

    I'm sure I introduced some oils into the system with all my PB blaster, so I skimmed today but no change in the spitting. Will probably skim a few more times.

    Likely as not some difference in the new location causes there to be more condensate in that location. Hard to say what that might be -- but that's all it would take.

    In another matter, timing is all very fine, but... do you have a low pressure gauge? If so, as I have said elsewhere, determining whether you do or do not have enough main venting is really easy...
    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
  • JUGHNEJUGHNE Member Posts: 7,853
    Is the portion of wet return at the boiler clean to allow condensate to return freely? In addition to Jamie's pressure question.

Leave a Comment

BoldItalicStrikethroughOrdered listUnordered list
Emoji
Image
Align leftAlign centerAlign rightToggle HTML viewToggle full pageToggle lights
Drop image/file

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!