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Main venting

Looking to replace old main vents with new ones. I have 3 mains in home (single pipe system) 60’ 40’ and 20’ long. I was split between Gorton 2 and B&J Big mouth. I see some people have multiple vents on a single main, should I have more than 1 vent on longer mains?


  • Yes, and you could tell when you have enough main venting by using a 0-3 PSI gauge, in addition to your 0-30 psi one.
    keep adding main vents, until you can see only a couple of ounces on the gauge as the air is being pushed out.
    A rule of thumb is one Gorton 2 for each 20 feet of 2 inch line, but as the goal is to have almost no back pressure impeding the air on its way out, the low pressure gauge method is more sure.--NBC
  • jiggy72jiggy72 Posts: 11Member
    Thanks for the feed back NBC. So for 60’ of 2” main I should have 6 Gorton #2?
  • JUGHNEJUGHNE Posts: 5,652Member
    One Gorton # 2 for each 20 feet of 2" main would be 3 G2's for your 60' main.
    One B&J Big Mouth vents about double of one Gorton 2.

    They are about the same price for each vent.
    The BJ looks to be the better investment.
  • jiggy72jiggy72 Posts: 11Member
    So I’m thinking 2 b&j big mouth vents for 60’ 2” main, 1 b&j for 40’ 2” main, and either 1 Gorton #2 or 2 Gorton #1’s for 20’ 2” main. Does that sound right? Should I be rearranging vents based on main length and pipe size?
  • gfrbrooklinegfrbrookline Posts: 369Member
    I would round up and put 3 big mouths on the 60' and 2 on the 40', you can't over vent the mains and massing out the vents worked wonders on mine, one 60' one 40'. Thank you New England Steam Works. No more short cycling and more even heat.
  • jiggy72jiggy72 Posts: 11Member
    ok i ordered big mouths for the 2 longer mains, but the short main (20' 2" main) I don't know if 1 gorton#2 is too much/just enough or maybe i should put 2 Gorton #1's would be enough?

    **side question....most pics i see show 2 mains on majority of steam systems...i have 3 that uncommon?
  • FredFred Posts: 7,851Member
    A Gorton #2 on that 20' main should be fine. Also, three mains isn't unusual, especially on larger systems or larger houses. In many cases, even when there are just two mains off of the Header, one or both mains may branch off further down the line and need vents on those branches as well.
  • jiggy72jiggy72 Posts: 11Member
    Is blue Teflon tape enough when installing main vents? Or should pipe joint compound or pipe dope or some other alternative be added too?
  • FredFred Posts: 7,851Member
    Teflon tape is fine and will make it easier to take the vent off to clean or replace it, in the future.
  • jiggy72jiggy72 Posts: 11Member
    Thank you Fred
  • jiggy72jiggy72 Posts: 11Member
    So I put main vents on, 2 big mouths on long main, 2 Gorton #1’s on short main. Anything I should change (piping setup)? Or it looks ok?
  • FredFred Posts: 7,851Member
    Nice job. It's hard to tell from the pictures but I assume you have a little pitch on those antlers that the vents are mounted on, to allow condensate to drain back into the main/return. Doesn't take much. If it holds water, turn your 45's just a little to get the pitch (if you don't already have it)
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