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Main air vents

Bernard Smith
Bernard Smith Member Posts: 49
in THE MAIN WALL
definitely a Hoffman 45( its a 3/4" thread). Obviously the wrong vent, right? I will try the Gorton 2. Where do I put the Gorton 1?

Comments

  • Bernard Smith
    Bernard Smith Member Posts: 49
    main air vents

    My main line is about forty feet long with one main vent at the end. It is a Hoffman No. 45. This end of the house has three risers, two of which are trouble free. One troublesome riser with two large radiators on it. The rest of the house heats up pretty quickly, but the end with the main vent on it is very slow. It takes about 40 minutes for the main line to get hot at the end where the vent is, meanwhile the rest of the house is already hot. Is this normal? Somebody recommended a Gorton No. 2 vent. The two large radiators have Gorton No. C vents. When system gets hot, the main vent constantly hisses. Is this normal. It is a three family house with 19 radiators total. It is only this particular riser that gives trouble. All newly piped two years ago. No problems with banging. A lot of water out of main vent when first installed but none in a long time
  • Bob W._3
    Bob W._3 Member Posts: 561


    The steam guys must be busy tonight. If it was my system, I would calculate the size of the main, vent it accordingly, and if it still needed help, vent the riser at the top rad. Your main is 45'. What diameter pipe? Post this and someone will figure out the correct venting. Three families? How high is the longest riser? What size pipe?
  • Bernard Smith
    Bernard Smith Member Posts: 49
    main air vent follow up.

    > The steam guys must be busy tonight. If it was

    > my system, I would calculate the size of the

    > main, vent it accordingly, and if it still needed

    > help, vent the riser at the top rad. Your main

    > is 45'. What diameter pipe? Post this and

    > someone will figure out the correct venting.

    > Three families? How high is the longest riser?

    > What size pipe?



  • Bernard Smith
    Bernard Smith Member Posts: 49
    main air vent follow up.

    The maim is 45 feet long, 3 " diameter, Longest riser is 28 feet long and 2" diameter
  • Bernard Smith
    Bernard Smith Member Posts: 49
    main air vent follow up.

    Thanks Bob, maybe you can assist me further.
    The main is 45 feet long, 3 " diameter, Longest riser is 28 feet high and 2" diameter
  • Bob W._3
    Bob W._3 Member Posts: 561


    According to my calcs that would be about 2.2 cu. ft. just in the main, which means a Gorton No. 2 and a Gorton No. 1 to vent that air at 2 oz. pressure. You said the main vent is a Hoffman 45? Hoffman lists that as a bottom inlet convector vent. Maybe it is a Hoffman 4A, which is a small main vent. You would need about 20 Hoffman 4A's to equal those Gortons. Try getting adequate venting to the main and see if the rads and risers heat. Bet they will.

    Edit: Check the size of the threaded connection for that main vent. If it is less than 1/2" it won't vent quickly enough.
  • Bob W._3
    Bob W._3 Member Posts: 561


    If the main is right at the end of the dry return, where it goes vertical, you could raise it up on a short length of pipe and then back on an ell, T or whatever, to mount both vents. I put a Y strainer below mine, per Hoffman recommendations. Putting the vents up and back will help protect them from any water hammer.

    Steamhead posted a picture on this thread:

    http://forums.invision.net/Thread.cfm?CFApp=2&Thread_ID=31459&mc=2#Message207142
This discussion has been closed.

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