Hackney plumbing
Homeowner
Dang it Terry, I thought I was going to understand your answer! Do you mean to say it wouldn't be wet vented if one or more of the lines were sized differently? And is wet venting the same thing as "S trapped?
Sizing does not determine if it's wet vented or not. If a fixtures vent receives the discharge from another fixture then its wet vented.
S trap is where the outlet of the trap(weir) extends below the bottom of the trap(j-bend) before it hits the vent. This is why pipe size has an effect on the distance the trap can be away from its vent. As you know drain lines pitch down and the farther away from the trap you get the farther down your going..........you can only go so far before your below the bottom of the p-trap. If you go too far you have piped a form of an s-trap.