Poorly Vented Sink?

[Tdallas1215]

Need some help with a bathroom sink that has a slow drain which is causing water to back up in the sink. The sink was poorly plumbed by a previous owner and originally had just an S trap into the floor which i heard is a half-ass way to do it. I attempted to install an inline vent as shown in this video:

[ame]https://www.youtube.com/watch?v=PGYRfPBpJVw[/ame]

I thought it was going to work because without the vent and just the elbow the sink drained great. After I screwed the inline vent on, it backed up again. Is there anything i can do to fix this venting issue without ripping up the floor? Would a p trap that eventually made its way to the existing sewer pipe work? Any help is appreciated.

 

[CT18]

Need the vent to come off the top and go as high up under the sink as it can.

 

[Tdallas1215]

Ok, I did some research, so if I can fit a p trap use that and right after the trap on the horizontal pipe I need to install a T, then some how route it back to the old pipe in the floor?

 

[CT18]

Move that tee up higher and pick up the trap off the branch and continue straight up with that AAV.

 

[Tdallas1215]

Ok, I think we are on the same page. It's weird though, if I take the aav off the stack pipe it drains 10x better. Will keep you posted!!

 

[Zeppelin5000]

I've never used an AAV before and can't see them working as well as a normal vent. I guess if it's all you can do to keep things in code, then it's better than nothing...

 

[CT18]

Yeah in a pinch they work and are legal here in my area of Michigan. I changed one at my buddies house that had failed and your nose will know when they need to be replaced.

 

[Tdallas1215]

Ok thank, I am working on configuring a P trap. Would you recommend branching the AAv off the horizontal section of the P trap or at the end of the horizontal section as if the sani t was the elbow? Which would be more effective?