First a little complaint, I had installed a $25.00 studor vent screwed on top of a lovely 18" 1.5" pipe almost to the top of my island sink... it was a thing of beauty... THEN HE CAME... and without my knowledge, my husband let the plumber cut it out and GLUE an inline vent in only about 6" above the drain...I was so ticked! He was there to fix a dragon in our drain (air problem) which my sink vent had NOTHING to do with and the dragon noise started back up again when the pressure built up so it's never been fixed!

Anyway...fast forward about 18 months, and my sink is backing up again...it seemed slow but not clogged so I test it by sawing a tiny slit right under the glued up inline valve and "voilà!" the water drains right down. The next day I cut it off completely and snaked the line the 25 feet my snake goes (just in case) and bought the materials to put a screw top on the pipe (still only about 6") and a new (cheap) inline valve.

I installed everything and it seemed to be working then POW it starts back flowing again. I unscrew the vent until air rushes in and sink drains. So, I figure it's because it's a cheap one. I'm at another home improvement store and I buy TWO oateys (super cheap) because I figure I'll have one one hand to just screw in when that one fails.

I've now tried both of them (three total) and the suction and back up is immediate. Again, when I unscrew, the water flows freely so I KNOW it's an air problem.

Before I go and buy the $25.00+ studor vent (and probably the fixings to raise the vent as high as it will go) is this really a case of THREE valves from two manufacturers being bad? Is there a way to test the ones I have by blowing or other means?

http://farm8.staticflickr.com/7378/11006264734_2c7f8826ae_b.jpg

I might have to ask about fixing the dragon after this... our plumber didn't seem to know how to fix it. :)

Hi Dcold

The drain line is still PARTIALLY clogged... won't allow the spring mechanism in the vents to drop.

Snake the drain line MULTIPLE times... should resolve the issue. For best result, see if you can keep water in the drain while snaking (set the faucet to a trickle until it almost overflows the pipe). This will let you know when you hit the blockage (will hear a WHOOSH! When you hear the whoosh, work the snake back and forth in that area and you should be all set!

Mark

The Dragon you hear is a air being sucked through the trap which vents the sink. The fact that you can take the AAV,(automatic air vent) off and the sink drains tells me that the air vent is faulty. I would go with the$25 Studor Vent and see if that doesn't quiet the Dragon. Let me know if raising the vent back up to 18 inches helps the sink drain better. Good luck, Tom