Is this wet vent of a toilet OK? Theoretical.

[Reach4]

This sketch illustrates a 1/2 bath trying to wet-vent the toilet. The WC closet flange is above a combo in the vertical plane. I understand that you may prefer coming in via a wye in the horizontal plane. I attempted to make a poll that asks about this configuration. I messed up on my first try at that. Maybe this will be my only try, but it is poorly worded too. My intention had been to make a longer poll to ask if it would be permitted under UPC and under IPC. I was going to ask if it would work perfectly well and should be permitted, even if it was not.

Then I would ask that if there was a jog down by a few inches at the green d, would that turn it from allowed to disallowed, and from should-be-permitted to should-not-be-permitted. Remember that you are not worried about preventing siphoning in a toilet.

Assume a cleanout is off the right side of the picture.

Comments?

 

[Plumber69]

This sketch illustrates a 1/2 bath trying to wet-vent the toilet. The WC closet flange is above a combo in the vertical plane. I understand that you may prefer coming in via a wye in the horizontal plane. I attempted to make a poll that asks about this configuration. I messed up on my first try at that. Maybe this will be my only try, but it is poorly worded too. My intention had been to make a longer poll to ask if it would be permitted under UPC and under IPC. I was going to ask if it would work perfectly well and should be permitted, even if it was not.

Then I would ask that if there was a jog down by a few inches at the green d, would that turn it from allowed to disallowed, and from should-be-permitted to should-not-be-permitted. Remember that you are not worried about preventing siphoning in a toilet.

Assume a cleanout is off the right side of the picture.

Comments?

View attachment 65205

I dont know what you are asking. This looks fine to me

 

[Sponsor]

 

[wwhitney]

Hello,

I was reading the IPC section on wet venting here: https://up.codes/viewer/ohio/ipc-2015/chapter/9/vents#912 (may have Ohio amendments). I don't see anything in it that says that in the situation pictured, the wye in blue has to be horizontal, rather than upright as shown.

There is, however, part of 912.2.1 which says "Where the dry-vent connects to a water closet fixture drain, the drain shall connect horizontally to the horizontal wet-vent system." I take that to mean that if in your picture, the lav was replaced with a shower without a dry vent, and the dry vent was connected to the toilet fixture drain before it combined with the shower drain (e.g. with a wye below the closet flange), then the upright wye in blue would not be allowed, and that blue wye would have to be horizontal.

So I think a misunderstanding of that requirement may be what has lead to the idea that the wye in blue (edit: for a toilet) always has to be horizontal for a wet vent.

Cheers, Wayne

 

[Terry]

So I think a misunderstanding of that requirement may be what has lead to the idea that the wye in blue always has to be horizontal for a wet vent.

Cheers, Wayne

I like the toilet dropping into a 90 which then wyes in to a horizontal wye, mainly because the only place I can think of where you could even fit a combo or wye fitting would be in the crawlspace or fairly deep ground work. Too often I see homeowners use a santee on it's back when they realize that the depth is becoming an issue. I would never drop a toilet into a santee on it's back.

Edited 8/20/2020
I just read Cool Blue Harley's post. So having the toilet wye off on the horizontal, something I've always done, is the best way it seems. No wet venting a toilet dropping into a vertical like that.

 

[James Henry]

Go to International code counsel website and type in the search bar " Bob scott plumbing venting: decoding chapter 9 of the IPC". His book shows a picture of that very thing that is not allowed. You have to own the book to see it. The picture was to large to upload. Try to find a diagram online of a wet vent that shows a toilet entering vertically. It would be similar to a drain entering a wet vent vertically. I am not bothered either way if anyone disagrees with this I am just trying to be helpful.

 

[Reach4]

Thanks for weighing in.

Go to International code counsel website and type in the search bar " Bob scott plumbing venting: decoding chapter 9 of the IPC". His book shows a picture of that very thing that is not allowed. You have to own the book to see it.

I presume that you are saying that it has a picture that is labeled as what not to do. Right?

It would be similar to a drain entering a wet vent vertically.

That would seem to be a reasonable follow-up. Suppose we fed the trap arm of a shower into a wye in the vertical plane. Would that be a problem? (really dumb idea crossed out)

 

[Jeff H Young]

Thanks for weighing in.
I presume that you are saying that it has a picture that is labeled as what not to do. Right?


That would seem to be a reasonable follow-up. Suppose we fed the trap arm of a shower into a wye in the vertical plane. Would that be a problem

I think all pipes must enter on the horizontal

 

[wwhitney]

That would seem to be a reasonable follow-up. Suppose we fed the trap arm of a shower into a wye in the vertical plane. Would that be a problem?

A shower trap arm always needs to be vented before the top of the trap arm goes below the invert of the trap weir, even when wet vented. So the trap arm had best hit the horizontal wet vent on the horizontal.

Since a toilet siphons, this consideration doesn't apply, and so I believe the drawing in the OP is OK.

Cheers, Wayne

 

[Reach4]

A shower trap arm always needs to be vented before the top of the trap arm goes below the invert of the trap weir, even when wet vented. So the trap arm had best hit the horizontal wet vent on the horizontal.

D'oh... did not engage brain for a few minutes. Thanks.

 

[Jeff H Young]

btw how do you vote? thats the craziest thing if you click on its an automatic yes?

 

[James Henry]

The picture is an actual photo of the installation similar to what you posted and is labeled as an incorrect installation with an arrow pointing to it and the caption" WC may not enter wet vent on the vertical". I just know I'll never put a toilet in that way.

 

[James Henry]

A shower trap arm always needs to be vented before the top of the trap arm goes below the invert of the trap weir, even when wet vented. So the trap arm had best hit the horizontal wet vent on the horizontal.

Since a toilet siphons, this consideration doesn't apply, and so I believe the drawing in the OP is OK.

Cheers, Wayne

We all know your intelligent Wayne but when you do plumbing for a living you have to follow the code or you won't be doing plumbing very long.

 

[Reach4]

If you have a crazy amount of depth to work with, sure wye not a vertical combo or wye. Kind of rare though.

45 degree toilet flange into a wye would probably be the shallowest in from the top. It would probably be very tricky to get the height right.

Imagine if you are trying to fit into 10.5 inch width between joists on 12 inch centers.

 

[James Henry]

You guys win.

 

[wwhitney]

you have to follow the code or you won't be doing plumbing very long.

Of course. Can you point me to a sentence in the IPC or UPC (or NSPC) that prohibits the toilet fixture drain from entering the horizontal wet vent on the vertical? Or does the book you reference have an explanation for the annotation on the picture, with a reference to a section in the code? I'm not finding anything, but I may have missed it.

Thanks,
Wayne

 

[James Henry]

This is a page from that book by bob Scott. the code cannot illustrate every scenario in every plumbing design because it would be 10,000 pages long and I think it leaves some leeway for the local jurisdictions to come up with their own interpretation. You can come to your own conclusion. I like to be safe than sorry.

 

[Reach4]

In looking up IPC 912.1 , I read on to 912.1.1 Vertical wet vent permitted Not related to what we are talking about here. That vertical wet venting is for up to two bathroom groups. Toilet(s) go last.

 

[Jeff H Young]

This is a page from that book by bob Scott. the code cannot illustrate every scenario in every plumbing design because it would be 10,000 pages long and I think it leaves some leeway for the local jurisdictions to come up with their own interpretation. You can come to your own conclusion. I like to be safe than sorry.

Thanks James henry! Ill take another look I think you said that was IPC and not UPC. We all have differant interest here. Sure Im interested whether something will work good, But whether it works well or is something I want to do once or 100 times Its Important to know whats legal. Ive plumbed several schools with gangs of W/C with combi on back my drain was real deep and I had a 4x2 wye on top for the vent but of cource it wasent in a 2x10 joist bay.
Again James thanks for picture dont know whoBob Scott is? but sure want to know the facts. If that is ilegal then exactly what would be left for an inspector to interpretate? Thats one thing I love about most codes there is no interpetation like the length of a trap arm or many things there is no interpetation there is legal or not legal . correct interpetration or incorrect interpetration

 

[wwhitney]

This is a page from that book by bob Scott

Thank you.

Evidently, Bob Scott thinks it's not allowed, but I don't see any code reference. So I think Bob Scott is misreading IPC 912.2.1, as I explained in my first post of the day.

Cheers, Wayne

 

[Jeff H Young]

Ive been reviewing chapter 9 both upc and IPC not seeing anything prohibiting how a watercloset or similar trap arm enters the wet vent? I really think if its not prohibited then it would be aprooved and there isnt an interpetation issue that I see. Next ill try googling bob scott.