Would appreciate critique of DWV Layout

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mikepdaviskc

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Hello,

I would greatly appreciate those who would have a look at this layout and provide feedback. You can't see in the picture but I'm connecting the vent for the sink on the right to the main vent with a santee and bushing. I realize the sink vent is probably not necessary but I've got the space.
What I'm not 100% sure about is the horizontal section and whether it's OK to have the wyes on their sides like I've got them.

Thanks, in advance,
Mike
 

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Dunbar Plumbing

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If the pipe leading vertical in the center of your picture is a vent for the tub, it will not fly.

You have to wash your vent otherwise over time...buildup/clogs will eventually seal off that horizontal section to the 9o.

Taking that drain line from the tub and teeing off at a degree no more than 45 degrees and rolling up that wall will correct that problem.

The first clog on that tub and waste will go back and seal off the vent.....with no way of knowing it is malfunctioning.
 

mikepdaviskc

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Rugged,

Yes, the center pipe is a vent and I thought there was something not quite right about it. Thanks for identifying it. If there is a rule I can learn here it sounds like you shouldnt have a horizontal section of vent tied to a horizontal section of drain? Or in other words, if any section of horizontal is wet then it all must be wet?

I'm not 100% sure I understand what you mean when you say "teeing off at a degree no more than 45 degrees and rolling up that wall" but I'll try again and post a new picture. What I'm thinking is the shower drain should connect to the top of a wye the vent should connect to the side of the wye (turned up 45%) and then turn a corner after the bottom of the wye to the drain.
 

Dunbar Plumbing

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Yes. Any vent that is connected to a drain must be washed by the fixture it serves....otherwise the system will not be designed "error-free".


On that tub run, turning a tee up out of that branch...you can lean it over no more than 45 degrees. The reason for this is that you can mimic the same situation once again in the way you have it designed. In this scenario, a clog comes about and will lay on that flat section, diminishing the flow of that vent.

If a clog happens twice....it can seal the vent off completely and no one knowing why the tub is constantly clogging. The "reason" is that the vent is no longer there....it's a ornament to your plumbing system not working.

The reason most codes enact no flat venting under 42" which is for the most part a golden rule for the distance above the highest flood level rim in a battery of fixtures.

Tilting that tee over on a 45 and no greater will allow for gravity to do its job and whatever clog occurs....it will slink back down into the drain and carry on to the drain system.

The great thing about codes; even if we don't like them sometimes, it took hundreds of thousands of case histories where product failed or caused other problems to become a statute in your local code book.
 

mikepdaviskc

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Rugged,

You've said I could use a tee to connect the tub run to the vent but I didn't think I could use a SanTee on it's back. If I could use a SanTee, I probably wouldn't have to turn it much at all.
 

mikepdaviskc

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How does this look?

Now I think I get what you mean about rolling the wye.
 

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hj

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critique

That vent Y should be on its back with the street 45 into it. Rolling it that way should not allow you to have the pipe vertical. Your lavatory drain is also incorrect because you have created an "S" trap.
 

mikepdaviskc

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hj,

I can turn the wye on it's back--I was trying to save a little space. I'm not sure why the lav drain is an "s" trap. The sink will have a p trap not seen in this picture and the vent will tie into the main vent also not seen in this picture. I don't honestly know that I understand the difference between a p and s trap anyway.

Thanks,
Mike
 

Dunbar Plumbing

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S-traps < not good

Switch that wye for the lav to a tee and that will correct that issue. Replace that wye for the tub vent to a tee; it looks like a tee is a better application anyway since it looks like you are in the confines of the wall already.

S-traps are notorious for siphoning the trap dry, losing it's protective seal of fluid to keep sewer gases from entering back through the drain.
 

hj

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s trap

Your line enters the wall and then drops down to the Y. That makes it an "S" trap. You need a sanitary tee for the connection to the vertical riser. If you use a combination Y-1/8 bend it will be more compact than your Y AND 1/8 bend. If your inspector will allow a sanitary tee on its back, (most will not in that location), that will be even more compact.
 

mikepdaviskc

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hj and rugged,

I'm really appreciating your help.

About S traps and inspections...I understand how what I had was an s trap now. Interestingly, I had the same configuration in a powder room that I had inspected. I don't think I'm getting much for my inspection dollars.

The first picture incorporates your suggestions. If space is tight I'll consider the santee instead of the comboWye because I don't think the inspector will even notice but I think I have plenty of room for the Wye.

Now back to that powder room. It is right below what I'm working on. I reconfigured it and it no longer has the s trap. It is the second picture. The 2" on the left is the drain that will tie into picture 1. The 1.5" on the right I will work up to the vent above 42" in picture 1. Any problems with this idea?

Thanks,
Mike
 

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mikepdaviskc

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Now that I'm looking at the powder room configuration it looks like I've created another s trap. Any Ideas on how to do better given this small space?
 

mikepdaviskc

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Now that I've thought about it a little more, I think my first floor powder room is OK. I think the sanTee is more turbulent than the wye which breaks the flow after the trap and keeps a siphon from forming. Since I have a SanTee after the trap, I'm OK. I think. Anybody?
 

hj

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piping

The vent off the top of the tee is what prevents siphonage, not the turbulence in the tee. In the main picture, one improvement would be to continue the line out of the Y over to the lavatory drain and eliminate that elbow in the line. Remove that cap at the sink and run the vent up and connect it to another one somewhere.
 

Racer814

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you could have just put a tee in your vent stack and armed over that foot and a half to the lav.....would have saved a lot of work and pipe......and then your original layout would have been fine as that section would now be wet vented.......a single 2" vent is sufficient to serve both those fixtures..
 

mikepdaviskc

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hj,

I agree about the elbow and I'm planning on incorporating that change...also, I'm planning on venting the downstream sink all the way to the top.

I think my design is solid enough now that I'm ready to start gluing. And I finally understand the s-trap, now. Down, up, down before vent=s-trap. Don't know why I found that so hard to understand.

Racer, I know I could have wet vented the whole group but a lot of people on this board seem to agree that, if possible, every trap should have a vent so that's what I aimed for. I'm a perfectionist, and an engineer--it's a sickness.

thanks,
Mike
 

Racer814

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you could put a 3" vent in place of a two on a lavatory and it won't work ANY better.......it's like reaching terminal velocity or critical mass....more only works better to a certain extent and then it's simply more.....that 2' dry vent in the original picture is still venting the shower, it's just wet now.......heck you could fill that sink up to the top and dump it and it would never, ever exceed the capacity of the 2" pipe enough to shut off the air...it's got nothing to do with being a perfectionist....you've never seen anyone more anal about his work than me....in fact you need to go back and straighten that drain a little...it's been killing me....j/k:)

Good Luck
 
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