Popular plumbing problem solving and remodeling DIY discussion advice forum site.

Venting inadequate with AAV Kitchen sink

Author: downstream (PA)

I have a Venting problem but I don’t know why.
This is a completely new installation. Pictures & diagram attached
2nd kitchen – 2nd floor only one kitchen per floor
Problem:
Sink drains very slow – several minutes if both sinks are half filled or one is block at strainer while other is draining.
If one sink is filled to near top and other sink is open- will drain most of the way then water comes up into empty sink and slow to drain the rest of the way for both.

if remove Studor Mini-Vent DMV AAV– water rushes down however water is present at Studor Mini-Vent DMV AAV also.

have experimented with different brand and style undersink vents.
Pictures show other vent, however now installed & using Studor Mini-Vent DMV AAV

ALL DW piping has a ¼” per foot pitch.
Center (between bowl) T has a deflector
T below Studor AAV is a sweep not a straight T
All piping is new from sink to 2” roof vent 15’ away.
Nothing else taps into this vent all the way to 3” horizontal in basement
Undersink is 1 ½” until just before T .
Undersink T until Roof vent is 1 ½” SCH 40
Undersink T till undersink Studor AAV is 1 /12” SCH 40
This is all on a septic not public sewage.
Double bowl SS sink is 33” X 22” total X 6” deep.
Kitchen is 2nd floor residential.
Height of top of vent above roof approx. 18” above top of sink.

Studor Mini-Vent DMV AAV
· Will vent up to 160 DFUs on a branch
· Will vent up to 24 DFUs on stack

Not being inspected. Looking for safe and functional.
Advice please
Diagram:
[@#$%&[picturepush.com]][/URL]

Pic 1:
[@#$%&[picturepush.com]][/URL]
or
[url]http://www2.picturepush.com/photo/a/8866905/640/8866905.jpg{/url]

Pic 2:
[@#$%&[picturepush.com]][/URL]
or
[www2.picturepush.com]

Re: Venting inadequate with AAV Kitchen sink
Author: WC (VA) Quote "This is all on a septic not public sewage". If this house is being lived in do any other fixtures have a drainage problem? What if you filled a bathtub at least 1/2 - 3/4 full and then drained it. Would it drain very slow or stop? Can you eliminate the sewage drain field as being so full that it will only allow slow drainage?

Re: Venting inadequate with AAV Kitchen sink
Author: North Carolina Plumber (NC) The aav is not the problem. Air is being trapped somewhere in the drainage system, due to a clog, low spot in the piping, etc.

Re: Venting inadequate with AAV Kitchen sink
Author: johnmyhandyman (NJ) I'm still having this problem too but with the washer machine.Is that inch and a half standard for sinks and washer machine stack pipes? Or is 2 inch standard for drain pipe?

Re: Venting inadequate with AAV Kitchen sink

Author: hj

You have given WAY TOO MUCH information. All we had to know is that removing the AAV allows drainage, with or without water in the AAV opening. That means there is air trapped between the sink and some obstruction in the drain. Where, or what, it is is something we cannot tell you without being there. It is one of those problems that would NOT happen with a conventional vent, although the cause would still be there.

Re: Venting inadequate with AAV Kitchen sink

Author: waukeshaplumbing (WI)

ive had this issue a few times with AAV's

every time it was a clog in the system

once it was underground on a old house....when they drain cleaned it it would work for 2 weeks, then plug up again....we camera'd it and there was a large belly in the pipe...food would collect after 2 weeks and it wouldnt drain again....removing the aav made it work though...

something clogging your pipes

Re: Venting inadequate with AAV Kitchen sink
Author: mr leak (CA) The tail piece meaning the vertical pipe should be not more than 24 inches. I would reconfigure the p trap as if you had only one sink then bring the other sink drain in from the side and install the AAV approx 4 inches above the drain. Sinks are 1.5 inch drains and laundry are 2 inch drains