Step 6 · Install the AAV
The final step is to attach the AAV itself. Most AAVs come with a threaded adapter. First, glue this adapter to the top of the vertical pipe you just installed. Apply primer and cement to the outside of the pipe and the inside of the adapter's socket, then push it on with a quarter-turn. Once the adapter is set, simply screw the Air Admittance Valve into the threaded opening. Hand-tightening is usually sufficient; do not overtighten with a wrench, as this can crack the plastic.