180 degree turn in toilet drain

[snucky]

I am re-plumbing my basement bathroom and am second guessing my plumbing route for the toilet. It currently enters at a 90, runs for 16", enters another 90, runs for 8" and takes another 90 before it runs straight into the main stack. I can easily give it a steeper slope to speed things up but am worried that solids may get stuck in the many bends. Expert opinion would be MUCH appreciated!

Below is a link to a picture of the current setup plus a floorplan for measurements:
http://reimann.files.wordpress.com/2011/09/drains1.jpg
http://reimann.files.wordpress.com/2.../floorplan.jpg

Thanks so much!

[LiQuId]

135 degrees is the maximum horizontal change of direction for a reason. 90's are bad news and not allowed in horizontal dwv either ( 2 45's makes a more gradual angle )

[johnjh2o]

Also use a Y and 45 instead of the sanitary tee.
If the trap is for a tub you would be much better off if it was a 2" trap with a 2x1-1/2" bushing. That will make it much easier to snake if need be. In most 2" is the minimum size pipe to be used under slabs.

John

[snucky]

Thanks guys for your input. If I...

- replace the 90 w/ two 45's and a nipple and
- replace the Tee with a Wye coupled w/ a 45

would you let this configuration pass?

Is the 135 degree rule on a horizontal run a builder's code? All I can find it for is code for clean-outs, not out ruling them per se.

Also, I'll reduce to 1-1/2" AFTER the Pee trap.

[LiQuId]

reducing the pipe diamter after the p-trap risks syphonage and reduces the distance to vent you are allowed.

135 degrees is CODE ( plumbing code here in canada, building code covers mostly structure ) there are similar codes in most places.

And the 2 45's dont need a nipple between them ( i know it seems odd ) they offer a more gradual change of direction so there is less turbulance ( which makes the solids and liquids separate and slow ) this is also code.

135 degrees HORIZONTAL change on on and fixture drain is MAX before it is served by a vent pipe. and anything smaller than 4" is MINIMUM 1/4 inch per foot grade.

[johnjh2o]

Originally Posted by LiQuId

reducing the pipe diamter after the p-trap risks syphonage and reduces the distance to vent you are allowed.

135 degrees is CODE ( plumbing code here in canada, building code covers mostly structure ) there are similar codes in most places.

And the 2 45's dont need a nipple between them ( i know it seems odd ) they offer a more gradual change of direction so there is less turbulance ( which makes the solids and liquids separate and slow ) this is also code.

135 degrees HORIZONTAL change on on and fixture drain is MAX before it is served by a vent pipe. and anything smaller than 4" is MINIMUM 1/4 inch per foot grade.

1-1/2 traps are not allowed under slabs as is 1-1/2 pipe.
I don't see how it would allow siphonage.

John

[snucky]

I will have to change my layout then to where I stay under 135 degrees with the toilet drain. Thanks so much for your guidance!

The reason why I went with 1-1/2" for the tub drain was that I was under the impression that the tub drains required the pipe be 1-1/2". I pulled up this product randomly:
Kohler Clearflo Slotted Bath Drain with Overflow | CSN Stores

[LiQuId]

larger volume of water creates greater corealis effect when draining, In theory this could lead to momentum syphonage as it enters the smaller diameter pipe it will have more draw. ( though i admit it is unlikely )

Compare the pipe to a syphon, a larger vessel is drained off by a smaller pipe assisted by gravity.

[LiQuId]

codes do require the pipe to be 1 1/2 MINIMUM ... you could use a larger pipe such as 2 "

Your tub also appears to be not vented.

[snucky]

Hi LiQuid,

i marked the vent location in this picture with a V - it's a 2" vent pipe located in the laundry room:
http://reimann.files.wordpress.com/2011/09/drains1.jpg

I wouldn't mind running the tub drain at 2" entirely. You're saying that fitting the actual tub drain wouldn't actually be a problem?

Thanks so much again, I'm learning so much!