Hi- Quick question. I have a toilet that drops vertical down 3 feet into a horizontal 3" sewer line via a wye/1/8 bend on its back. The back inlet (horizontal part) of that wye is connected to another 3x2 wye on its back that serves a 2" lav drain (wet vent) that continues 2" through the roof/vent stack. Does that 2" lav drain/wet vent serve to vent the toilet, or do I need a separate vent for the toilet before it drops into the main. It would seem that the toilet could suck air through that 2" vent once the waste enters the 3" horizontal section, and since the toilet is a syphon/self priming anyway I don't see why it would need a separate vent. This is in upstate NY,

Thanks!

-Mike

that setup would have been fine IF the WC drain did not drop strait into the horizontal drain. IF the Wye for the WC came off at 45 or less then the lav drain could have served as a wet vent.

if the 3x2 "Y" was in the vertical toilet drain at no more than 20" below the floor, it would pass MA code..

Thanks for the replies.
So, I either have to roll the 3x3 wye to its side at 45* or less and drop the toilet in, or I guess I could also change things up a little more and put a 3x2 Y in the vertical section and drop the lav into that 2" line instead as long as its within 20" of floor?

Can anyone explain more slightly in depth as to why the wye on its back is not permitted to wet vent the toilet? I'm thinking it has something to do with blocking the flow of air at the top of the horizontal section of pipe (the wet vent) as the water comes through the wye.
-Mike

i think i am understanding you correctly??
a "Y" on its back is fine for venting but it your case the location of the 'Y' is wrong..

packy, I understand what you are saying about the location of the 3x2 y being wrong for wet venting(that it needs to be in the vertical section of the toilet riser to vent the toilet, but what I am still wondering about is why putting the 3x3 Y for the toilet drain rolled up at 45* or less (as Doug mentioned) would also work if I kept the 3x2 Y where it is (upstream of the 3x3 Y,on its back picking up the 2"lav sink which is vented through roof)

Thanks again

i think doug was trying to say roll up to 45 deg or more to be acceptable. below 45 deg is not acceptable. i think???