A wye or combo on it's side is fine.
The other post was with a sewage pump, and none of us plumbers agree with that one inspector.
Wyes and combos for waste can be used vertical or horizontal the way you have asked.
I'm plumbing in a new 3" waste for a new toilet on the second floor. I have my 3" PVC waste pipe dropping down into the crawl space and I'm tying it into one of the existing 3" horizontal waste pipes down there. There are two changes of direction: vertical to horizontal, for which I'm gonna use a long sweep wye with a clean out on its heel, and then there's a 90 degree horizontal right turn it needs to take. For this I'm thinking I need to use a 45 degree street bend into a 45 degree wye to change the horizontal direction by 90 degrees and enable the waste to flow into the existing 3" horizontal waste pipe. Attached is a crappy drawing of what I'm trying to achieve.
My concern is that I've read that a wye in the horizontal plane needs to be rotated at least 15 degrees (so the input is 15 degrees above the horizontal). Is this correct? Or is that rule only to be applied in specific circumstances?
Also, there's another waste pipe to the right of the vertical pipe which is preventing me from twisting the long sweep 45 degrees to its right and just using a 45 wye without the 45 degree street bend for the horizontal change in direction.
Last edited by AnimalHungry; 10-05-2013 at 03:02 PM.
Great, thanks Terry! So I can just use the 45 degree bend into the 45 wye (on its side) to give me the 90 degree change in horizontal direction.