DIY advice for Infinity drain install and venting

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John Gayewski

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Thanks John!


View attachment 80671


I was thinking of using a 2" Combo for the trap arm/vent intersection rather than a Sani tee for better flow. For some reason, in my mind I'm thinking sani-tees are not allowed under ground? I could be wrong of course.
You can't use a combo vertically like that. The trap needs a clear line of sight to the vent. With a combo positioned like that the vent opening ends up being below the trap weir.
 

Terry

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For a trap arm on the vertical it's always a santee.
On the horizontal it's a wye or combo fitting.

horizontal-plumbing-drain-lines.jpg


index.php
 

wwhitney

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John's suggestion is a great one.

If you really want to minimize how much footing you have to chop out, and if the linear drain is a bottom outlet drain that is actually at the edge of the footing as shown, you could do the vent as follows: (I'll sketch you an isometric if the narrative isn't clear enough):

Chop out for the drain riser (tailpiece) to hit a p-trap with the U-bend pointed away from the double wall to hopefully get the drain outside the footing. Then point the elbow outlet of the p-trap at a diagonal to the right and towards the bottom of the page. Then almost immediately hit a wye. The wye is going to be rolled 45 degrees above horizontal (minimum for a dry vent takeoff) and with the branch inlet (vent) pointed towards that double wall. The vent will have to go back through the footing to get to under the double wall, then it will hit a 60 to turn vertical.

The lower the p-trap, the deeper you have to chop into the footing for the drain riser and the vent. But if you have the p-trap too high, the vent could rise out of the slab before it gets under the wall. You want a minimum of 2" of concrete over the 60 degree elbow's non-vertical leg, 4" would be better.

Cheers, Wayne
 

Dan Park

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You can't use a combo vertically like that. The trap needs a clear line of sight to the vent. With a combo positioned like that the vent opening ends up being below the trap weir.
I think I understand now what you are saying.
I will use the 2in Sani tee as pictured below:
Screenshot_20220203-173730_Chrome.jpg


And not the long wye combo.

Screenshot_20220203-152812_Chrome.jpg

Your explanation of clear path makes sense since when you look through the sani tee through the curved part, there's a clear access/air space to the vertical 2in opening.
Whereas if you look through a long wye combo on the curved opening, there is no air space to the vertical 2in opening. I think I understand the logic behind it now. Thanks for that clear explanation John!
 

Dan Park

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John's suggestion is a great one.

If you really want to minimize how much footing you have to chop out, and if the linear drain is a bottom outlet drain that is actually at the edge of the footing as shown, you could do the vent as follows: (I'll sketch you an isometric if the narrative isn't clear enough):

Chop out for the drain riser (tailpiece) to hit a p-trap with the U-bend pointed away from the double wall to hopefully get the drain outside the footing. Then point the elbow outlet of the p-trap at a diagonal to the right and towards the bottom of the page. Then almost immediately hit a wye. The wye is going to be rolled 45 degrees above horizontal (minimum for a dry vent takeoff) and with the branch inlet (vent) pointed towards that double wall. The vent will have to go back through the footing to get to under the double wall, then it will hit a 60 to turn vertical.

The lower the p-trap, the deeper you have to chop into the footing for the drain riser and the vent. But if you have the p-trap too high, the vent could rise out of the slab before it gets under the wall. You want a minimum of 2" of concrete over the 60 degree elbow's non-vertical leg, 4" would be better.

Cheers, Wayne
Thanks Wayne! Yes if you don't mind doing a sinple linear mockup of your idea would be great!

That's my worry with this scenario is if I have enough depth for the linear drain/p trap. This is because since I'm doing a curbless shower, I was thinking my slab for the shower needs to be around 1.5 inches lower than the lav/toilet area slab because the linear drain has to be the lowest point in the shower area and I was thinking of using deck mud to make the slope towards the linear drain. Overall, this reduces my height for where the P trap is in relation to the mainline. I should have enough slope to the mainline but I just have to chip it out and figure it out I guess.
 

John Gayewski

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Thanks Wayne! Yes if you don't mind doing a sinple linear mockup of your idea would be great!

That's my worry with this scenario is if I have enough depth for the linear drain/p trap. This is because since I'm doing a curbless shower, I was thinking my slab for the shower needs to be around 1.5 inches lower than the lav/toilet area slab because the linear drain has to be the lowest point in the shower area and I was thinking of using deck mud to make the slope towards the linear drain. Overall, this reduces my height for where the P trap is in relation to the mainline. I should have enough slope to the mainline but I just have to chip it out and figure it out I guess.
If you need to minimize height you a regular 90 and a Street santee.

A90 vertically doesn't need to be a long sweep.
 

wwhitney

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Thanks Wayne! Yes if you don't mind doing a sinple linear mockup of your idea would be great!
Here's a somewhat crude attempt at an isometric. I'm not 100% sure that it involves less footing breaking than John's idea.

Cheers, Wayne

Option.jpg
 

Jeff H Young

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Thats What wayne was talking about being illegal in ca plumbing code 908.2.4 and 908.2.5 spell it out that last drawing wont pass inspection .

Dan Park, the combi vertical for the trap arm connection is a no no in every code only a san tee there.
 

Dan Park

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Here's a somewhat crude attempt at an isometric. I'm not 100% sure that it involves less footing breaking than John's idea.

Cheers, Wayne

View attachment 80677
Oh wow, I understand what you did there!

The purple dry vent line comes off of a 2" wye rotated or "rolled" at 45° angled upwards from the 2" trap arm off the shower's P trap.

I will try this solution as well after I jack hammer out some concrete tomorrow, lol.

Thanks Wayne!!
 
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Dan Park

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Thats What wayne was talking about being illegal in ca plumbing code 908.2.4 and 908.2.5 spell it out that last drawing wont pass inspection .

Dan Park, the combi vertical for the trap arm connection is a no no in every code only a san tee there.
Thanks Jeff! Yep I understand it now from John's explanation and Terry's graphics. Makes sense finally!

For the 908.2.4 and 908.2.5, are u referring to Wayne's multi colored drawing or one of my drawings or both, lol
 

Jeff H Young

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Thanks Jeff! Yep I understand it now from John's explanation and Terry's graphics. Makes sense finally!

For the 908.2.4 and 908.2.5, are u referring to Wayne's multi colored drawing or one of my drawings or both, lol

I was talking about post #38 I said #58 my bad each post has a number in small text at top right. the shower needs to branch off downstream of the toilet and its vent .
Waynes post #50 multi colored drawing is good for a vent just for the shower . toilet vent elsewhere
Reviewing previous posts I see your not looking to conform but function , looks like it functions it well
 

wwhitney

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The purple dry vent line comes off of a 2" wye rotated at 30° angled upwards from the 2" trap arm off the shower's P trap.
Right. Just to clarify, you rotate the barrel of the wye 45 degrees from a horizontal (well, 2%) starting position. That makes the slope of the side branch change from 0 degrees (well, 2%) to 30 degrees. If you rotated the barrel another 45 degrees, the side branch would be coming off the top, and so sloped at 45 degrees (since it's a wye fitting)

Cheers, Wayne
 

Dan Park

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Right. Just to clarify, you rotate the barrel of the wye 45 degrees from a horizontal (well, 2%) starting position. That makes the slope of the side branch change from 0 degrees (well, 2%) to 30 degrees. If you rotated the barrel another 45 degrees, the side branch would be coming off the top, and so sloped at 45 degrees (since it's a wye fitting)

Cheers, Wayne
Yes, I think I understand your explanation. Sort of like what is shown in the pic below I gather:
Screenshot_20220203-222555_Chrome.jpg


But in my case I'll roll the 2" wye off of my shower drain's trap arm. The trap arm will eventually continue and connect with my 3" mainline (as shown above in John's multicolored diagram)
Once I complete this dry vent and mainline connection, I can then join the WC directly to the 3" mainline downstream from the shower connection which in turn creates a wet vent scenario for the WC.

Is this the correct way to think about it? Thx!
 

wwhitney

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Sort of like what is shown in the pic below I gather:
To clarify, like in terms of the wye's configuration, but not in terms of what is upstream of the wye's branch. For a proper dry vent, the wye's branch needs to continue to under the wall, where it hits a 60 degree elbow to turn straight up.

Cheers, Wayne
 

Dan Park

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To clarify, like in terms of the wye's configuration, but not in terms of what is upstream of the wye's branch. For a proper dry vent, the wye's branch needs to continue to under the wall, where it hits a 60 degree elbow to turn straight up.

Cheers, Wayne
Sounds good! I'm going to mockup my abs fittings and pipes first before I start jackhammering to make sure I have enough space. I'll keep everyone posted.
 
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