90 degree horizontal bends 3" pipe- please help!

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twal

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Okay, so here is the current design for a difficult to plumb bathroom group. The lav is plumbed with 2" and acts as a wet vent for a tub (plumbed w/ 1,5") and a toilet. The trap arms are all within the length limits denoted by UPC and sloped at 1/4". The question I have is about the horizontal 90s that the toilet drain must make in this setup. A 3" pipe drops straight down to a long sweep 90 taking it horizontal, there is a clean out and then it connects to the wet vent with a combo. Right after this combo it has to make one more 90 (a combo with a cleanout) to then shoot straight out of the house and to the sewer. I am aware of the 135 degree rule for horizontal turns (as I understand, after 135 degrees a cleanout is needed, but then more turns can be made). What I don't understand is if the first combo (where the toilet trap arm joins the wet vent) is counted in this 135 degree rule. Obviously these 90s are less than ideal, but the house in question is very constrained with regards to where it can be vented (joist right under a bathroom wall, cathedral ceiling, etc.) I am very much hoping for some advice here as to both the code compliance issue (in WA, so UPC) and your take from first principles. Here is a picture that will hopefully help you understand what is going on. If I am breaking the 135 rule I don't know how I would rectify because I don't even have room between the combos for another clean out. Any help is greatly appreciated. Be well!

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wwhitney

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This doesn't speak to your question, but couldn't you reconfigure your drains per the green diagram below? Or maybe the perspective is misleading and something doesn't fit.

But here's a textual description of what I'm trying to show with the green line. Call the direction the 2" wet vent is draining "towards the camera", and then the perpendicular horizontal left/right. [The camera is actually looking more to the left.]

Then the upper horizontal 3" line is just extended to left so that it can 45 down to a wye in the lower 3" line to the sewer as far left as possible without requiring you to redo the lefthand vertical. The WC drops down below the joists and immediately 45s to the right, so it is going to the right as it falls. Then at the bottom it hits a LT90 to turn towards the camera.

Meanwhile, the 2" wet vent 45s to be moving to the left and towards the camera, crossing in front of the WC's LT90 so that the WC can hit it in a wye's branch inlet. This combined drain then 45s to hit the "straight shot to sewer".

Cheers, Wayne

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twal

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Hi Wayne,
I am very grateful for your response. I went ahead with your proposed reconfiguration and am feeling a lot better the whole thing. The WC now has a total of 90 degrees horizontal change and it is split between two 45s (the wyes). While this fix cost me another 100 dollars and good bit of my time, it was a good learning experience and I am much more confident in my design now. I do have 135 degrees of horizontal change in my wet vent now (had 90 before), and while I am not totally sure what the code has to say about that, I think it is way better than the situation I had before. So, really, thanks a lot!

Hopefully, now, I am up to code and have an efficient enough system. I left a couple clean-out options intact and hopefully that was a smart move...
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wwhitney

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I'm not really up on the cleanout requirements. My only comment is that I'm not sure if the cleanout on the WC fixture drain is necessary, but a 3" or larger cleanout is supposed to have a 24" x 24" clear space in front of it. So if there's less space than that between the cleanout and the wall, then it would be appropriate to add another elbow or two to the cleanout portion to bring the access to a location with the proper clearances.

For the code rules on cleanouts, see UPC Section 707. Here's California's version, because for some reason up.codes doesn't have WA's version.


Cheers, Wayne
 

Jeff H Young

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I wouldnt bother w cleanout against wall as its wihen 5 ft of mainline that is served by c/o. if it was glued up Id run with first picture . BTW c/o in crawlspace need to be withen 5 foot of the entry point at least in ca
 

twal

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Thanks Wayne and Jeff for your thoughts on this.
It is a bit deceiving in the photo, as I have a full 36" between the cleanout on the toilet trap arm and the stemwall. While it might be unnecessary I can't imagine it would cause a problem (unless I don't understand something... very possible, ha!) and it does seem like it may one day prove useful if a clog were to occur between there and the mainline cleanout. I also found this in the code:

1002.3 Change of Direction

A trap arm shall be permitted to change direction without the use of a cleanout where such change of direction does not exceed 90 degrees (1.57 rad). Horizontal changes in the direction of trap arms shall be in accordance with Section 706.3.
Exception: For trap arms, 3 inches (80 mm) in diameter and larger, the change of direction shall not exceed 135 degrees (2.36 rad) without the use of a cleanout.



Doesn't this suggest that the cleanout I have on the trap arm is actually required? Since I have a 45 followed by a 90 on the trap arm. Unless they are only talking about horizontal changes in direction...

The cleanouts themselves are in fact >5ft from the opening, but nonetheless readily accessible in my opinion. That seems like a really arbitrary rule-what's the thinking behind that?

As for the first setup vs the current setup (recommended by Wayne) I will sleep a lot better not thinking about those two horizontal 90s back to back. This is my own house that I am working on and my first time doing any plumbing, so peace of mind is worth a lot to me right now.

Cheers,
Tyler
 
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wwhitney

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I think you're good on the cleanouts.

FWIW, I would be inclined only to count horizontal change of direction. And even if not, the WC trap arm only has 135 degrees of direction change, you're not over the 135.

Cheers, Wayne
 

Jeff H Young

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Its fine photo is decieving c/o looks very close to stem wall. I really think youll have a good working system.
 
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