I am installing a sink in my basement and want to tie into the drain from the sink above. However, I am unable to tie into the existing vent for the main floor kitchen sink. Can I install an aav onto the horizontal drain pipe on the basement sink inside the sink cabinet. The horizontal pipe is 5 feet long before it ties into the main kitchen drain. Any diagrams I have found show the aav installed on the vertical drain pipe with a T I would not be able to add the aav on the vertical kitchen drain because it is behind the wall.

AAVs are always installed in a horizontal position. They can be on the horizontal pipe or at the top of a verticle pipe which drains down. How to Install an Air Admittance Valve | DoItYourself.com

No problem here... ;) See images.

As long as the AAV is under the cabinet and "readily accessible" for future swap out should the AAV fail then it can go on the vertical or the horizontal as in my pictures.

Questions? Let us know, OK?

Mark

Thanks so much. The picture of the horizontal is great.

Thanks for the link