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 Wet vent for toilet...
Author: campervanman (CT)

Hi All.

I'm planning a second story bathroom installation. Currently we have one bathroom on the first floor. This is at the rear of the house, with a horizontal waste pipe running through the basement and out to the sewer through the front of the house.

I'm planning on having the toilet and sink on one side of the bathroom, and the bath tub on the other. I think I'm OK for the tub, but have some questions on the toilet/sink combination.

At present I am planning to run 3" waste horizontally for about 12" inches from the toilet, then taking a 90 degree sweep and dropping through the first floor into the basement and into the horizontal waste to sewer. To vent the toilet, I'd like to run a 2" wet vent from the 3" pipe up into the attic, en route taking a 1 1/2" drain from the sink.

First question - is this wet venting permissible for the toilet? My research suggests it will be, but...

Second question - if the above is possible, can I put in a wye fitting right after the 90 degree sweep to accept the wet vent? Or, does the vent need to come out of the top of the horizontal waste from the toilet? I understand that the vent has to leave at an angle equal or greater than 45 degrees, but I'm not sure if it is permissible to add the vent lower down the stack than where the toilet drains?

If it helps, I'm in CT! Thanks for any input - my ears are open!

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 Re: Wet vent for toilet...
Author: getplumbingsupplies (Non-US)

well first..im in canada..but..we cant use 90's on drainage lines.unless its right off the toilet..use two 45's...

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 Re: Wet vent for toilet...
Author: campervanman (CT)

Sorry, I wasn't clear - I will also use two 45s, not a 90 (except a street elbow off toilet as you suggested!)

Thanks!

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 Re: Wet vent for toilet...
Author: packy (MA)

you don't need to roll the "Y" up to 45 with a wet vent.
it is good if you can but not necessary.
see if this picture helps?
the drain/vent combo (wet vent) must be 2".
[smg.photobucket.com]

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 Re: Wet vent for toilet...
Author: campervanman (CT)

Thanks Packy. If I'm understanding you correctly, then what I am proposing should work, right? I will be using 2" for vet vent up through the roof above.

I guess my main concern is that the vent vent will enter the 3" pipe below the level of the 3" horizontal pipe from the toilet. In my head, this shouldn't affect the atmospheric pressure etc and should work just as well as if I had the wet vent entering the top of the 3" pipe, but I want to make sure I'm not missing something obvious. As the vet went will be entering on the vertical drop, it seems I'd have to have a major backup before it could get blocked, unless the drain part of the vet vent got blocked by discharge from the sink of course!

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 Re: Wet vent for toilet...
Author: dlh (TX)

normally you would use a sanitary tee to go vertical from horizonta and come off the top for the vent but if you dont have the room for some reason then a wye below the 90 will work

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PLUMBERS "Protecting The Health Of The Nation"

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 Re: Wet vent for toilet...
Author: hj (AZ)

Most inspectors would want a sanitary tee where you drop down from the toilet, rather than an elbow with a vent connection below it.

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 Re: Wet vent for toilet...
Author: campervanman (CT)

Thanks DLH and HJ. I had initially ruled out the sanitary tee due to space requirements. However, since then I've had to drop the ceiling level in the closet below, so I think it might be doable. I might have to angle the 3" pipe from the toilet a little more steeply so that I can fit in the sanitary tee with 2" wet vent extending up below the finished floor level.

I really appreciate everyone's reply - really helpful! THank you.

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 Re: Wet vent for toilet...
Author: rudythplbr63 (AK)

Good Morning hj, I know of NO code that allows a tee on its back for a change of direction. The 3"X2" wye on the horizontal, with the 2" leg above the invert of the 3" will be sufficient.
I know wet vents are legal, however I've a plumbing inspector (a retired pipefitter) that doesn't understand them, so he won't allow us to use them. They are the best way to keep the toilet waste clean.

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 Re: Wet vent for toilet...
Author: campervanman (CT)

Hi Rudy!

My understanding of HJ's post was that the sanitary tee would be in an upright position. Waste from toilet coming in horizontal, vet went from above and waste to sewer out of the bottom.

I did want to put the 2" wye on the horiztontal, however because of the closet wall underneath the only way to do this would be to have the wet vent tee draining towards the toilet rather than towards the sewer, which I realize is not good!

I hope my inspector likes (and understand wet vents!) THat sucks!

Thanks for your help!

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 Re: Wet vent for toilet...
Author: Scott the Plumber (PA)

hj was referring to a vertical tee in sanitary position, not a horizontal tee on its back.

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 Re: Wet vent for toilet...
Author: hj (AZ)

WE did not say "ON ITS BACK". I said extending vertically from the tee in place of an elbow. In the first place the only way I could see a tee on its back would either be under the toilet, which we did not even consider, or as "bull head" configuration, with the outlet dropping down out of the side port, which would be patently illegal.

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 Re: Wet vent for toilet...
Author: hj (AZ)

I hope he understands you also, because I have no idea what you are trying to convey.

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 Re: Wet vent for toilet...
Author: dlh (TX)

wow, am i invisible or what?

the inspector shouldnt have much say in it as long as your local codes allow wet venting

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PLUMBERS "Protecting The Health Of The Nation"

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 Re: Wet vent for toilet...
Author: bill plumber (FL)

I don't understand why anyone would dry vent when they could wet vent. With a wet vent you know if your vent is obstructed. To answer the posters question you absolutely do not need to roll up or enter the drain line on top with a wet vent. You will need to stay two pipe sizes larger than minimum for the entire length of the wet vent. Can you wye off the horizontal 3" to the toilet for your wet vent? Some inspectors would consider wet venting the toilet after dropping vertically to be an s-trap.



Edited 2 times.

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 Re: Wet vent for toilet...
Author: packy (MA)

bill, massachusetts wet venting say 1 pipe size larger.
i totally agree. wet vent is 1000 times better than dry vent.

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 Re: Wet vent for toilet...
Author: bill plumber (FL)

so you can run 1 1/2" to a lav for a wet vent with another fixture draining into the wet vent?



Edited 1 times.

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 Re: Wet vent for toilet...
Author: x apprentice 22 (MA)

2" for a wet vent for a lav in Massachusetts.

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 Re: Wet vent for toilet...
Author: bill plumber (FL)

What is the minimum size for a lav drain?

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 Re: Wet vent for toilet...
Author: hj (AZ)

The toilet is ALREADY an "S" trap which is why it would be an inspector's decision whether he would allow the "extension" of the "S" trap.

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 Re: Wet vent for toilet...
Author: hj (AZ)

The only difference between a "wet vent" and a "dry vent" is the few feet of piping carry the fluid from the upper fixture. IF the venting is done correctly, you do NOT need a wet vent. IF you are venting horizontally, then you DO need a wet vent to compensate for the installation.

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 Re: Wet vent for toilet...
Author: hj (AZ)

Not sure WHAT you are asking there, but the WET part of a wet vent has to be at least 2".

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 Re: Wet vent for toilet...
Author: hj (AZ)

1 1/2", but it would usually be into a 2x 1 1/2x 1 1/2 tee, or something similar.

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 Re: Wet vent for toilet...
Author: bill plumber (FL)

if the minimum size for a lav p-trap is 1 1/4" than 2" wet vent is two pipe sizes larger not one size larger.

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