Idiot or Genius?

JohnCT

Probably the former, but tell me what you think anyway.

I'm trying to add venting to my 90' of 2" main. Right now, there's a 1/2" tapping at the end of the main that I've got 2 G4s on. I'm assuming that's maxed out and there are no other existing taps or plugs. About a foot before the end of main drop, there is a riser that goes up about 4' into the house to a valve with no radiator (removed when the room was reconfigured and a woodstove added). If the pipe in this part of the basement is like the rest, they've probably removed the asbestos from the pipe, and left it on the fittings, so I'm guessing no one is going to be too excited about drilling into that. In addition, there is little clearance between the pipe the beam it runs under, so it would have to come out sideways.

My bright idea: What if reduced the unused valve to 3/4" and put 3 G4s on that? Other than having to explain to friends what an antler of vents was doing in my living room, is there any reason this wouldn't work or why I shouldn't vent into my house? Pictures attached.

Ironman

I'd recommend that you take the existing vent tap and immediately increase it to 3/4" using a close 1/2" nipple and a bell reducer. Then replace the G4's with 3 big mouth vents.

JohnCT

Thanks, Ironman. I apologize for being a little thick, but I'm new to this. Are you suggesting putting a shorter half inch nipple on the existing tap, then the reducer on that, followed by a 3/4" antler of vents? If yes, is that 1/2" hole really capable of pushing any more air than the current vents can handle?

Ironman

That's what I'm suggesting.

A short length of 1/2" is not gonna cause that much restriction. Have you ever looked at how small the opening is in a gas cock? Yet, because it's a very short length, it doesn't significantly restrict flow. Same thing here.

EBEBRATT-Ed

What @Ironman said .....or if asbestosis not encountered remove the old radiator pipe nipple coming up through the floor and install additional vents on this pipe in the basement.

That being said you should be able to vent 90 feet of 2" through a 1/2" nipple with the proper vents

BobC

If that 1/2" port is hand tapped directly into a fitting you may find it difficult to go up to a 3/4" tight hand tapping. If it is a reduced 3/4" tapping just remove the tapping and go for it.

If the 1/2" port isn't suitable for enlarging you could use that unused radiator feed for one or two bigmouth vents assuming nobody objects to how it looks.

Or you could try a saddle fitting like this -

https://forum.heatinghelp.com/discussion/167449/main-vent-install-with-saddle-clamp#latest

Bob

JohnCT

Ironman—thanks. Wasn’t sure what a gas cock was so looked it up on my computer at work. Based on some of the search results I got, l’ll probably get a visit from HR on Monday.

EBEBRAT: Great idea to remove the riser and install there. Perfect location on the main about a foot before the drop.

BobC: Didn’t dawn on me that 1/2 pipe might be reduced. Probably not since the old vent I removed was 3/4” sitting on that pipe with a reducer, but I’ll unwrap the pipe and take a look. That would solve the problem.

Thanks to everyone for the input!

JohnCT

OK-used a bell reducer to increase to 3/4” and a 3/4”/1/2” tee so I could keep my G2s and add Big Mouths on 3/4” pipe. Anyone see a problem with the setup in the picture?

Fred

It would be better if your antler had all the vents on one side and if you could incorporate a couple 45's on it so you could get some pitch back to the main so that condensate can drain. Try what you have but if you see any vents spitting, change it up.

Neild5

It would have been better if you used black pipe instead of galvanized.

Ironman

How fast is it venting now?

JohnCT

Ironman: Pretty fast. About 5 minutes from the boiler starting to the vents closing, but the mains were still warm from before I shut it down to install the new vents. What’s a good time to aim for?

Fred and Neild5: Thanks for that input. If I see any problems, I’ll rework it with black pipe and some pitch.

Ironman

Your looking from the time the boiler starts steaming until the time the vent closes.

Danny Scully

Math always helps. An open 1/2” pipe can vent 4.8 cfm @ 3oz. A Gorton # 2 can vent 2.2 cfm @ 3oz, and the big mouth can vent 3.6 cfm @ 3oz. SO, you have 4 vents capable of venting 11.6 cfm @ 3oz connected to piping that can vent 4.8 cfm @ 3oz. Additionally, 90 feet of 2” contains 2.07 cubic feet of air.

JohnCT

Ironman: much different story with cold pipes. Tried it yesterday after the boiler idle all day due to burning wood. 13 minutes start of boiler to main vent close. Just a few minutes from the time I hear air until they close. Is that good or bad?