doesn't look right

Saw this yesterday in a bathroom remodel. Bathroom being remodeled is next door to another full bath and sinks are back to back. Plumbing for the sinks is a 45 double wye on a 3" pipe that runs 6' to vent stack. All horizontal. That's it. I'm assuming the plumber will put 45s on each side of wye for the traps but there is no venting except for the stack 6' away. Won't the sinks siphon water out of one anothers traps if a check vent isn't put on one of them?? There aren't any plans for a check vent.

sounds like they've oversized the drain pipe in order to get maximum internal venting in the pipe. Not the best way to do it; causes other problems which may be deemed of lesser magnitude than an open P trap, but still not right.

david

sinks

What goes into the end of the double Y? If it is a dead end, then it is the same, but larger, as when a 2" drain is run horizontally and a 2 x1 1/2 double elbow is used for the two sinks. It must be a very thick wall if a double Y and 1/8 bends will fit inside it.