Sat., Aug. 20, 2022 This is the magic of a time-tested plumbing loop vent for island sinks. Don’t take the shortcut using an AAV. (Tribune Content Agency) ...

Q. My new kitchen is going to have a large island with my double-bowl sink in it. The young plumber and my contractor want to use some newfangled thing that just fits under the cabinet.

The short horizontal pipe draining your kitchen sink needs to be a smaller 1.5-inch pipe to restrict the amount of water entering the loop vent. The loop vent system looks like the giant letter P ...