Air Admittance Valve

an Air admittance valve or AAV is a negative pressure-activated, one-way mechanical vent, used inside a plumbing system to eliminate the need for conventional pipe venting and/or roof penetrations.

A discharge of wastewater causes the Air Admittance Valves to open, releasing the vacuum and allowing air to enter plumbing vent pipe for proper drainage. Since Air Admittance Valve will only function under negative pressure situations they are unsuitable for all venting applications, such as venting a sump, where positive pressures are created when the sump fills.

Using Air AAV's can significantly reduce the amount of venting materials needed in a plumbing system, increase plumbing labor efficiency, allow greater flexibility in the layout of plumbing fixtures, and reduce long-term roof maintenance problems associated with conventional vent stack roofing penetrations.