Bathroom Drain Vent

[Jim Shannonhouse]

I've been noticing a foul smell when I turn on the water in our second bathroom. I looked under the sink, and the drain vent comes up higher than the trap, but the vertical vent pipe ends under the sink with a slotted cone cover over the end of the vent. Aren't drain vents supposed to tie into the vent stack that goes up to above the roof, and tie in at a point higher than the the level of the sink?

[Jerry Peck]

I've been noticing a foul smell when I turn on the water in our second bathroom. I looked under the sink, and the drain vent comes up higher than the trap, but the vertical vent pipe ends under the sink with a slotted cone cover over the end of the vent. Aren't drain vents supposed to tie into the vent stack that goes up to above the roof, and tie in at a point higher than the the level of the sink?

You are describing an Air Admittance Valve (AAV).

From your description, I would say that it was: a) installed wrong; b) not installed correctly; c) installed not as it should have been installed; d) or is defective and needs to be replaced.

Usually, from my experience, d) is caused by a), b), or c). :)

[Garry Sorrells]

If it is black then it is the wrong AAV. and has failed.
Replace with code accepted AAV.

[Vern Heiler]

Many times small insects like spiders get caught in the seal of the valve, with most of the AAV's I have dealt with you can unscrew the top of the valve and flush them out with water.