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/.
Click here to Find a Contractor in your area.

Main Vent

NRTDave Member Posts: 48
Hello, I am a new guy who has just recently discovered what I didn't know about "steam heat". And "everything" is the short answer.
My main has 1 vent only and that is a Vent-Rite #77. It must be real old. The piping [with asbestos] has probably been in place since the days of coal.
I was surprised to easily remove the locking nut by hand and remove the "bullet" part of the vent. It almost fell off. I guess the lower parts stayed in place.
Anyway I would like a new replacement that I can change out as easily as makes sense. I think it has a 3/4" thread.
Oh yes, I don't want cheap, I need good, if that helps.
Thanks for reading and educating me to this wonderful world.



  • Brad White
    Brad White Member Posts: 2,398
    Time to do it right

    If you have a single main as it seems (probably what now, 2-inch? As if I am a sage... :) post the length so that a proper venting arrangement can be made. A tree of smaller vents may get you faster venting and with less potential for damage. You probably will have to remove the remains of the vent base to get a new nipple in there.

    Is the current vent held back from the end of the main at least a foot or foot and a half?
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • NRTDave
    NRTDave Member Posts: 48
    Time to do it Right

    Hello Brad, I couldn't agree more. This is the "time to do it right". I'll have to get back to you with the length of the main tomorrow,as my son is living in the house in another city.
    I did measure the near boiler riser piping on the relatively new Burnham, and it measured 2 1/2" OD. So if the main stays consistant, you are probably exactly right with 2" pipe.
    As I said, I'll measure tomorrow. Should I measure the length of the lines that break off the main also? No vents on those though.
    "Is the vent 12 to 18 inches" from the end of the main? It seems that the main goes directly to the end of the house and the riser goes up. Also at that point [probably with a tee or some other fitting] the main line also makes a 90 degree turn and goes another 12" or so only. That is where the vent is. Not exactly on the straight main, but a small distance 90 degrees to the right.
    Also, the vent top is only a half inch or less from the floor boards above. I would have liked to see more room.

    Brad, thanks for the response and I'll do more measuring tomorrow. Please let me know if there is anything else that would be meaningfull to you.


  • Brad White
    Brad White Member Posts: 2,398
    A Venti Doppio Latte Please

    Hi Mike- Having fun are we? :) Yep.

    Where that "end of main vent" is, concerns me. Picture if you will on cold start-up. Some water beads up and collects in the invert (inside bottom) of the pipe.

    Steam comes along, picks up that water and carries it at some velocity into the end of the main. That water will find that vent and likely damage it. By having the vent off the top and back from the main allows the steam and water to pass safely below it.

    With what you have, I would at least put another nipple or two with an elbow on that vent and pull it back if you can so that the steam/water slug (if you ever have one) will have to really work to hit that vent. I would even split the last nipple with a tee and install the vents in the top like antlers. See the attached for a picture.

    Don't worry about the branches to the radiators- those are the responsibility of the radiator vents to take care of.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • NRTDave
    NRTDave Member Posts: 48

    Brad, I am having great difficulty in posting.
    I'll try again tomorrow.
  • NRTDave
    NRTDave Member Posts: 48
    vent.pdf won't open

    vent.pdf doesn't open for me. Would you please verify that the file is good and resend?

  • download the file as is (it will save it to your computer called attachment.cfm) Then change the file extension to pdf and it will open.
  • NRTDave
    NRTDave Member Posts: 48
    PDF File Problem Fixed

    Steam In My House, thanks. Problem solved, file downloaded and printed. Knowing what to do really helps. :-)

    Thanks again.

  • Big Al
    Big Al Member Posts: 35
    Mine is piped wrong

    The main vent in my house is piped directly above the return drop, not 15" back, but about 10" up from the elbow. It never spits or hammers . . . just a gentle whoosh and then silence. For the sake of reliability, I just replaced an ancient looking Trane vent that was still working in that location.

    I could re-pipe 15" back, but would need to deal with asbestos. I'd rather not.

    Maybe the configuration of the main, pitch, size of the drop, etc. is more than adequate, so the vent never gets clobbered. If it seems to work so well, should I be concerned?

    Thanks in advance,

  • NRTDave
    NRTDave Member Posts: 48
    Took Measurements Earlier

    Hello again. I took the following dimensions this AM and I hope they are of use.
    That 2" main travels 28ft to make a right turn via a 90 deg elbow, then on 14" to a tee where the riser goes up. From the tee 9" more to another 90 deg elbow going up. Inside the 2" 90 deg elbow is a bushing that accepts 3/4 thread. The Vent-Rite #77 is screwed into the bushing.
    Once in place there is less than a 1/4" between the top of the vent and the wooden floor boards above. It wouldn't surprise me if the vent didn't have to go in in two pieces.
    That is what I found and I am at a loss as to how to deal with it correctly.
    Thanks for reading and any comments that you might make.

  • Fred Harwood_2
    Fred Harwood_2 Member Posts: 195

    With apologies for the test.
  • Main Vent

    I asked for and received great advise from Ken at Gorton earlier today. Ken's customer service is outstanding. Others have said that, I can now confirm that myself.
    I will branch 2 Gorton #1 vents for my main.
    Then I'll tackle the rads.
    Thanks everyone for your guidance.


This discussion has been closed.