I am installing a new toilet in a new bathroom on the 2nd floor of a 100 year old home. The floor joist cavities are not deep at all (<6"). The only way I can make the 90 degree turn out of the toilet flange is by using a 90 degree vent ell (3") as it has the smallest circumfrance between the two openings. The AHJ plumbing inspector did not have any issues with me installing this, but the plumbing supply shop mentioned that I should keep a plunger handy.
I understand that since the inside of the vent ell is so small, there might be clogs if someone uses lots of toilet paper, etc, but how serious of a problem is this? Reallistically, I don't have any other choice but to use this but I want to see what you guys think before I glue everything in!
You may be better off with a ABS street 4x3 closet 90 bend, and then using a 4" closet flange slid over the top.
The closet flange, if needed, can be notched around the 90.
This keeps things real close, and provides a nice sweep.
I should have taken a picture of the Wed job on this.
The cast fitting was snug against the floor, and I had plenty of room for this to work. Going into the 4" cast fitting, was a 4x3 fitting reducer and a 4" Fernco inside hub seal. You have to beat the fitting reducer in, buy when it's there, it will never leak.