# Question for the high rise plumbers.



## RW Plumbing (Aug 16, 2010)

I was in a high rise today (40 stories) and the top floors seem to have water jumping up and down in the traps quite a bit. The building is always under a negative pressure and the VTR's just come straight through the roof. Occasionally, the positive vent pressure is enough to blow out the water from p traps. We talked with an engineer, who seems to think throwing goose necks on all the vent terminals will solve the problem. Anyone have and experience with this?

Any thoughts?


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## Mohr Mech (Aug 7, 2012)

We have had similar problems. If you install an H vent on top it will allow the wind to pass without causing back pressure on the vent. You just need. 3 sanitary tees. Put the bull of the first tee on the vent stack then attaché the other two to the sides of the bull headed sanitary tee facing up and down.


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## Relic (Sep 30, 2012)

Sounds like a venting issue. Can you verify that the relief vents are done properly? Whats happening is the traps are being siphoned. Does this happen on all the traps throughout? Adding an air admittance valve should relieve the problem.

edit: Just read this was the top floors. Definitely not a relief vent then. I think Mohr Mech got it right.


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## Gettinit (May 9, 2012)

There use to be a section of code that states that traps are not allowed to move up or down more than an inch. Much like being turned down for workmanship, it was never an issue. I can see this happen in my house. I have PVC pipes, single story, one bath has a 2" vent through the roof and the other has a 3" vent. It isn't a problem, but it happens. It is definitely can be fixed by dealing with the venting.


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## RW Plumbing (Aug 16, 2010)

Gettinit said:


> There use to be a section of code that states that traps are not allowed to move up or down more than an inch. Much like being turned down for workmanship, it was never an issue. I can see this happen in my house. I have PVC pipes, single story, one bath has a 2" vent through the roof and the other has a 3" vent. It isn't a problem, but it happens. It is definitely can be fixed by dealing with the venting.


Yeah exact same thing except there is enough pressure at times to blow out a trap.


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## RW Plumbing (Aug 16, 2010)

Mohr Mech said:


> We have had similar problems. If you install an H vent on top it will allow the wind to pass without causing back pressure on the vent. You just need. 3 sanitary tees. Put the bull of the first tee on the vent stack then attaché the other two to the sides of the bull headed sanitary tee facing up and down.


Any place where I can find out more about this H vent? Sounds like something designed to fix the problem, I could see this doing more than a gooseneck. I want to learn more about it though before I pitch it. Some of the VTR's are 8" so I don't want to pitch it without really knowing about it.


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## MarkToo (Dec 17, 2011)

Depending on the building's location etc., oscillation can be a major and ongoing trap seal loss issue.

Cutting the vent terminal on an angle can make a big difference. I've done it in the past and it worked - looks goofy but...


(We used to do it on the carburetor float bowl vents back in my drag racing days to keep the fuel from being siphoned up and out of the bowl by the air rushing into the carb).


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## OldSchool (Jan 30, 2010)

A rain cap over top might help like on a chimney


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## Tommy plumber (Feb 19, 2010)

When I lived in S. Florida, we had hurricanes hit in 2004 & 2005. In one storm, I remember seeing the water in my toilet bowl moving up and down (they were 3.5 gpf tanks and bowls). It was due to the wind moving accross the top of my roof and acting upon the vent.

Could it be unusually windy on the top of this 40-story high-rise?


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## Mohr Mech (Aug 7, 2012)

Never seen it in a code book an old plumbing insoector used to make us do it on high rises. The buildings we did it on we're 400 to 800 ft tall and right on the beach with heavy winds. They make h vent chimney caps for this same reason


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## Mohr Mech (Aug 7, 2012)

A goose neck won't fix the problem as you need some where for the back pressure to escape that builds up from high winds going across the opening of the pipe


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## OldSchool (Jan 30, 2010)

Then somebody should invent a swivel 90 with a weather vein on top ... So it's always out of the wind


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## Mohr Mech (Aug 7, 2012)

Look up h pot venting for a chimney that will give you the explanation you are looking for


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## RW Plumbing (Aug 16, 2010)

After drawing out the h vent it just seems to make sense. I'm pitching it to an engineer as long as he gives the green light I'm putting that in.


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## Plumbus (Aug 4, 2008)

OldSchool said:


> Then somebody should invent a swivel 90 with a weather vein on top ... So it's always out of the wind


Looks like somebody has.


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## RW Plumbing (Aug 16, 2010)

Man I look like a star now. Thanks for everyone's help. Especially Mohr Mechanical. I found tons of applications for the H pot vent in chimneys and it looks like its employed for the exact situation I'm encountering. When I do the job, I will post pictures of what it looks like.


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