Installing an Air Admittance Valve


A common problem in plumbing remodeling is figuring out how to run new vent lines when access to the existing drain-waste-vent system is blocked by some structural element.

One option is an air admittance valve. These valves are gravity-operated devices that respond to the negative pressure of draining water and open to let air in. Then gravity closes the valve, keeping sewer gases out of the room. Depending on the valve and the size of the vent, AAVs can support one or multiple vent lines. Local codes govern the use of AAVs in place of vents.

Prestart Checklist

About an hour to cut and assemble five or six pipes and fittings

PVC saw or backsaw, miter box or power miter saw, deburring tool, felt-tip marker

Cutting and measuring pipe, working methodically

Sketch drain/vent assembly; clear a path for the pipes

Primer and cement for your type and size of pipe, P-trap, air admittance valve, drain pipe

Step 1

Install the PVC drain line, the sanitary tee, and the P-trap for sink. The appropriate coupling for the AAV (glued or threaded) attaches to the tee. Check the manufacturer's instructions and local codes to determine the proper height for the AAV above the drain.

Step 2

Depending on the type of fitting, glue or screw the AAV in place.

Step 3

Depending on local codes and the AAV model, the completed installation should look something like this.

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