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New England DIYer
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25 Posts
Discussion Starter · #1 · (Edited)
I haven't glued anything together yet but I was wondering if this was ok to do? Now that I mocked it up I was just concerned that it won't vent ok and that I should have made part of it more flat for venting? That's a 22 degree 1.5" elbow in the middle and main stack is 4" sch 40 pvc.

Also I intend to put a slip joint into the elbow and use a SS trap with the j-bend piece going into the slip joint. Does anyone know if it's ok with RI code to have a horizontal slip joint? I read somewhere that MA doesn't allow it.

Thanks for your feedback!
 

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Roofmaster
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3,731 Posts
No, That wont work. Suggest you buy a book regarding the theory behind plumbing and read it.
 

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New England DIYer
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Discussion Starter · #3 ·
No, That wont work.
Care to explain why that won't work and how to do it right? I've looked in several books and no situation is ever exactly like the ideal pictures they show. I am familiar with venting and traps and why they are needed which is what made me second guess this setup. I am aware that that pipe is too small to be a wet vent if that's what you think I was trying to do. thanks
 

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Plumber & Gasfitter
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128 Posts
Unsure of RI plumbing codes, but assuming the laws of physics work the same over there, the slope of the trap arm is far too steep and will siphon out your trap upon draining the sink. Assuming that the 4" stack is able to be used as a wet went (most likely not), the maximum distance between the eventual p-trap and the stack should be roughly 6 feet, if using 1 1/2" pipe, and the slope no more than 1:50 or 1/4" per foot.

However, you could just stick a cheater vent between your 90 coming out of the wall and the p-trap, and it should work fine. Not sure if it'll meet code in RI though.
 

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Premium Member
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11,793 Posts
Care to explain why that won't work and how to do it right? I've looked in several books and no situation is ever exactly like the ideal pictures they show. I am familiar with venting and traps and why they are needed which is what made me second guess this setup. I am aware that that pipe is too small to be a wet vent if that's what you think I was trying to do. thanks
As apprentices, we looked at books for at least 4 years. Also looked at the work in the field at the same time and yes there are multiple ways to vent. But yours is far from correct. By my code(UPC) it has no vent. Its only a branch line
 

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Master Plumber
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1,615 Posts
the pipe vertical a tee sanitary coming off that pipe running horizontal must be at the correct height usually about 18 inches from the finished floor. to your sink drain center.
 

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New England DIYer
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25 Posts
Discussion Starter · #7 ·
Ok, so I suppose I should use one of these tees:

and run the pipe horizontally, not more then 1/4", down slope per foot, similar to the image below, except I have a soil stack venting to the roof so mine is 4".



Is it still be ok to use 1.5" pipe for it all or should I used 2"? I've read a wet vent requires one size up from the normally necessary size, but I'm not sure if this would qualify as a wet vent anymore if I do what I mentioned above. FYI the distance is only about 32" from the from where I want the drain to enter the wall to the stack.

The trap I plan to use (something like this:
) would probably be 1.5", so should I make everything in the wall 2" to be on the safe side or would that just make bad flow?
 

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Master Plumber
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1,615 Posts
You got it, only thing is that you can only reduce the vent stack down one pipe size above the sanitary tee.. now in your area code may allow something different due to the cold weather.
 

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New England DIYer
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25 Posts
Discussion Starter · #9 ·
Ok thanks. The side inlet on the 4" sanitary tee is 2" inlet, and 1.5" is only one step down from that, so I suppose I will use that.
 

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Doing it myself
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3,838 Posts
From what I know about plumbing codes, you cannot wet vent a pipe receiving discharge from the second floor.


:eek:
 

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Roofmaster
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3,731 Posts
Looking at books, and reading and understanding the theory are not the same. Thats the same as doing something for 20 years because someone told you how to do it without ever questioning why. It is entirely possible in that case to do it wrong for 20 years.

The theory behind pipe slope is as follows: Too little slope and the solids fall to the bottom of the pipe. Too much slope and the liquid(in this case water) runs away from the solids. in either case, the result is a severely clogged pipe in short order.

AT just the right slope, solids stay suspended in liquid, and just enough turbulence occurs in the pipe to scrub the walls on the way out. This of course requires an adequate amount of water for the amount of waste being carried, and also on the smoothness of the interior of the pipe.

The rule of thumb used to be 48 pipe diameters on venting, so it looks like you are OK as that is 72 inches in your case, but sometimes local codes requires vents to be closer.
 
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