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Main Vents--Installation approaches

btc Member Posts: 43
In reading the Wall last week, this post surprised me very much with regards to installing main vents:

"....is probably 2-inch [main].... but even if it's 1-1/2-inch, I'd use two Gorton #1 or Hoffman #75 vents on it. The added resistance of the smaller main warrants two vents. Mount them near the end of the main.

If there is no tee to pipe them into, you can drill and tap a 3/8" pipe thread hole in the side of the pipe (or the top if you can get to it) increase to 1/2" with a reducer coupling or elbow, and pipe the two vents on a 1/2" tee.

The drilling and tapping isn't a textbook move, but I do it often and have never had a problem."

This runs counter to all literature I have read on the topic. Why not take the time to add a Tee--on the return if the main is not accessable--and provide an opening greater than 3/8"?

Dont mean to criticize any approach, this just caught my attention as it runs counter to Dans book and all other literature on the subject.



  • well, 3/8th inch

    should be plenty as the vents orifice is not that big. im sure everyone would like to cut tee's into piping at the homeoewners expense all the time. but sometimes they just want there problem solved as quickly and cheaply as possible.
  • Steamhead
    Steamhead Member Posts: 16,287
    That was me, BT

    and was inspired by Frank Gerety, who is one of several geniuses Dan H. wrote about in PM this month. Frank wrote a book called "How to Get the Best from One-Pipe Steam" in which he describes this method, which he calls "Master Venting". Of course, I had to try it myself.

    Frank was right- it works! I have never had a problem doing it that way. Can't argue with success!

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