Wet venting a Gerberit inwall toilet with sink drain

[Dan Park]

Hello folks

Here's my setup for wet venting an inwall toilet by Gerberit in a master bathroom.

3in for the toilet is coming down going into a wye with a 2in wet vent/drain for the bath sink. Off the sink drain wall Tee, there will be a 1.5in vent to the sky.

From the toilet 90 to the wet vent is about 3 feet.

Any problems with this setup or corrections I can do? Any advice is appreciated.

Thank you for your time and advice!

 

[Terry]

2" vent through the roof does it.

 

[Sponsor]

 

[Dan Park]

2" vent through the roof does it.

I will scratch the 1.5in vent after the wall sink drain wye and do 2in to the sky.

Thanks Terry!

 

[Dan Park]

2" vent through the roof does it.

Is the 3ft distance for the 2in wet vent from the 3in 90 ok? I don't need to put a wye with a cockeyed dedicated 2in vent pipe closer to the 3in 90?

I'm a little concerned the 3ft length is too far since there's no air supply in that section. I'm sure the flush won't occupy the whole 3in pipe but maybe could happen once in a while?

 

[wwhitney]

Is the 3ft distance for the 2in wet vent from the 3in 90 ok?

Yes, UPC (operative in California) allows up to 6' measured along the pipe from the closet flange to the vent.

Cheers, Wayne

 

[Dan Park]

Yes, UPC (operative in California) allows up to 6' measured along the pipe from the closet flange to the vent.

Cheers, Wayne

Much appreciated Wayne! Thanks for the confirmation

 

[Dan Park]

Going off of Terry's post about running a continuous 2in wet vent to the roof for the closet flange, how many max 90degree bends can I have in that 2in vent run to the roof?

 

[wwhitney]

Once the vent is above the flood rim level of all the fixtures it serves, the number is unlimited.

However, it is still desirable to minimize them and use 45s over 90s when possible The resulting arrangement needs to drain fully if you blocked the outlets and filled it with water to the roof, then unblocked it. So don't create any traps.

Cheers, Wayne

 

[Tuttles Revenge]

Back to the original picture.. your wye looks like its coming up at an angle and using fittings to bring your 2 drains back to horizontal.. that sort of negates the fitting as a vent because it blocks the free flow of air from the invert/top of the pipe. (*tho isn't that what any reducing wye fitting does?*)
to truly be a wet vent that wye should be horizontal - 1/4" min and max grade. You can then drop to your main after that.

 

[wwhitney]

Back to the original picture.. your wye looks like its coming up at an angle and using fittings to bring your 2 drains back to horizontal.. that sort of negates the fitting as a vent because it blocks the free flow of air from the invert/top of the pipe. (*tho isn't that what any reducing wye fitting does?*)

I don't think it's true that a horizontal wet vent has to be pitched at exactly 1/4" per foot slope. I think you could pitch everything at 4" per foot slope and it would work fine. And I'm not aware of any language in the IPC or UPC that would preclude that.

Cheers, Wayne

 

[Dan Park]

Back to the original picture.. your wye looks like its coming up at an angle and using fittings to bring your 2 drains back to horizontal.. that sort of negates the fitting as a vent because it blocks the free flow of air from the invert/top of the pipe. (*tho isn't that what any reducing wye fitting does?*)
to truly be a wet vent that wye should be horizontal - 1/4" min and max grade. You can then drop to your main after that.

Thanks for that insight tuttles!
Yes I agree I had to put a 22 degree fitting before the wye for the 2in horizontal sink drain and the wye to connect. The slope for the 3in before the wye is slightly more than the sink horizontal 2in before the wye.

To mitigate the free flow of air potentially being hampered, I cockeyed the wye so the 2in offshoot of the wye is slightly higher than the 3in part of wye going to the closet flange. See pic.
This way, even if someone is using the sink and flushes at the same time, there should be enough air from the 2in wet vent to push the water down as the 2in drain with the 22degree fitting cannot be completely filled as I made that section a little more proud than the 3in section going to the closet flange.

I can also redo the pipe to what you stated as well if it doesn't meet code as I still have everything opened up.

Hopefully my explanation made some sense.

 

[Dan Park]

Thanks for that insight tuttles!
Yes I agree I had to put a 22 degree fitting before the wye for the 2in horizontal sink drain and the wye to connect. The slope for the 3in before the wye is slightly more than the sink horizontal 2in before the wye.

To mitigate the free flow of air potentially being hampered, I cockeyed the wye so the 2in offshoot of the wye is slightly higher than the 3in part of wye going to the closet flange. See pic.
This way, even if someone is using the sink and flushes at the same time, there should be enough air from the 2in wet vent to push the water down as the 2in drain with the 22degree fitting cannot be completely filled as I made that section a little more proud than the 3in section going to the closet flange.

I can also redo the pipe to what you stated as well if it doesn't meet code as I still have everything opened up.

Hopefully my explanation made some sense.

If you were looking straight on the wye, it would look like this where the 2in connection is slightly raised.

 

[Reach4]

I don't think it's true that a horizontal wet vent has to be pitched at exactly 1/4" per foot slope. I think you could pitch everything at 4" per foot slope and it would work fine. And I'm not aware of any language in the IPC or UPC that would preclude that.

I suspect there will be some interesting comments on that.

 

[wwhitney]

I suspect there will be some interesting comments on that.

Well, for the UPC (applicable to the OP), 911.3 on circuit venting limits the horizontal slope to 1" per foot. The absence of any similar requirement in 908 on wet venting certainly says that horizontal slope is not limited for wet venting.

Cheers, Wayne

 

[Tuttles Revenge]

That configuration of fittings doesn't look like it allows for the free flow of air ( i assembled a 3x2 wye as shown with 22's and I dont think it does) just like a combi isn't used as a trap arm where a san tee is.

 

[Reach4]

Well, for the UPC (applicable to the OP), 911.3 on circuit venting limits the horizontal slope to 1" per foot. The absence of any similar requirement in 908 on wet venting certainly says that horizontal slope is not limited for wet venting.

Cheers, Wayne

https://up.codes/viewer/california/ca-plumbing-code-2016/chapter/2/definitions#2 says

Horizontal Pipe. A pipe or fitting that is installed in a horizontal position or which makes an angle of less than 45 degrees (0.79 rad) with the horizontal.
​

Looks like you are on to something.

 

[Plumber01]

I don't think it's true that a horizontal wet vent has to be pitched at exactly 1/4" per foot slope. I think you could pitch everything at 4" per foot slope and it would work fine. And I'm not aware of any language in the IPC or UPC that would preclude that.

Cheers, Wayne

Here in Seattle it is mandatory the vent come off horizontal to allow free flow of air, I'm sure thats why Tuttles cited that.

It may not be required in different jurisdictions.

Take a look at example #3

https://www.google.com/url?q=https:...FjAAegQIChAB&usg=AOvVaw2bgzuK8e1XQlEUXCLbsutn

 

[wwhitney]

Take a look at example #3

Example 3.3 certainly looks weird, but I can't actually find any language in 908 that clearly prohibits it or that differentiates between 3.1 and 3.2 (labeled as compliant) and 3.3 (labeled as non-compliant). And as a practical matter, if the arrangement shown in 3.1 performs well, why would the arrangement in 3.3 perform any differently?

Here in Seattle it is mandatory the vent come off horizontal to allow free flow of air, I'm sure thats why Tuttles cited that.

Regardless of the above, as Reach4 pointed out, any angle less than 45 degrees above level is considered horizontal. So the layout shown in the OP, with a single 22.5 degree elbow, is still horizontal, and it is comparable to Example 3.2 (compliant) and not Example 3.3 (labeled non-compliant without any code reference).

Cheers, Wayne

 

[Reach4]

Regardless of the above, as Reach4 pointed out, any angle less than 45 degrees above level is considered horizontal. So the layout shown in the OP, with a single 22.5 degree elbow, is still horizontal, and it is comparable to Example 3.2 (compliant) and not Example 3.3 (labeled non-compliant without any code reference).

There are wet vents, and there are trap arms. Example 3 complains about a trap arm, and not a wet vent.

 

[wwhitney]

There are wet vents, and there are trap arms. Example 3 complains about a trap arm, and not a wet vent.

Page 9 of the PDF is labeled at the bottom "Example #3" but it has 5 diagrams labeled Example #1 through Example #5, which I am calling Examples 3.1 through 3.5.

Example 3.4 labels a trap arm non compliant, and it clearly violates 908.2.3.

Example 3.3 labels the dry-vented lavatory drain/wet vent connection to the lower horizontal wet vent non compliant because of a short intervening vertical section, but I don't see anything prohibiting interspersing vertical wet vents and horizontal wet vents. Anytime a dry-vented lavatory wet vents a WC or shower, you have a vertical wet vent followed by a horizontal wet vent; where's the prohibition on the sequence vertical wet vent / horizontal wet vent / vertical wet vent / horizontal wet vent?

Cheers, Wayne