critique my drain layout - is this an S-trap?

EDIT: Please delete this thread and see my other thread:



https://terrylove.com/forums/showthread.php?35335-DWV-Layout-Problems&p=251594#post251594

if the trap weir is above the lowest part of the inlet it is a siphoning trap.

Damn you're right - I forgot about that part. I just check and I think I can just squeeze the whole assembly under the bottom edge of the joists - so I could run a dedicated vent. I could tie the vent in using a 90 elbow with side inlet as shown in this adjusted diagram. This would place the weir at or below the vent inlet. Will this work?

No. For starters that would create a horizontal vent below the overflow rim of the shower, which would be the very minimum level, and even that would be lower than the required distance. Time to go back to the drawing board. But just for my edification, where would you ever find a 2" "three way" sanitary elbow. The smallest I have ever seen was 3" with a 2" side inlet. Your original drawing was a "perfect" S trap.

thanks. Well I am almost out of ideas. This is a very frusterating sitaution because I have what seems like a ton of space to work with, a nice 3 inch main right below to tie into, and a nice 3 inch vent 2.5 feet away - yet I cant come up with a single elegant solution to tie a drain in with a proper trap.


Here is one more (and maybe my last) idea. HJ you were right about the side inlet elbows being 3x3x2/1 1/2 at the smallest. This setup would still divert the trap across the main horizontal - but then this would pitch in the opposite direction from the main until it reached the wall where it would tie into the bottom of the 3 inch main drain/vent stack with a 3x3x2 side inlet elbow. Is this a permissible use of that style elbow? Is a rapid 180degree direction change going to cause problems? All that is upstream of the side inlet elbow is the kitchen sik and bathroom sink. the toilet will wye in downstream.

Because of the way the elbow is made, the vent connection would still be too low. In addition, that use is not normally approved because the side branch does not usually have a "sweep" which is required for drainage purposes. Give us a drawing of the ROOM, or at least the area around the shower so we can try to come up with a better plan. I have some ideas but have to know what you are working with. Your problem is that you came up with a design, and are fixated on making it work, rather than seeing alternatives.