Discover everything you should know about air admittance valves (AAVs) and how you can install one yourself to save time and money.

By BH&G Editors
Updated July 01, 2020
Butcher Block counter top
Jay Wilde

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. It might seem like all hope is lost, but don't let that small roadblock get in the way of your dream kitchen makeover. One solution is an air admittance valve or AAV. 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. However, before you begin installing an air admittance valve, check with your local building inspections office as local codes govern the use of AAVs in place of vents.

  • Start to finish 2 hrs
  • Difficulty Kind of Easy
  • Involves Plumbing Skills

What you need


How to do it

Part 1

air admittance valve illustration
Credit: Illustration by Art Rep Services, Inc.
air admittance valve illustration
Credit: Illustration by Art Rep Services, Inc.
Step 1

Understand How AAVs Work

Before you install one, it's important to understand how AAVs work. Air admittance valves are operated by gravity. When water and waste move down a drain line, it creates negative air pressure in the pipe. This negative pressure lifts the sealing washer and lets air in, which allows the waste to drain away freely.

When the negative pressure ceases, the sealing washer falls back in place. Earlier versions of this device were spring-operated. Such units are still available but are not reliable and don't meet code in most places.

air admittance valve illustration
Step 2

Determine Placement

Air admittance valves are typically placed between the P-trap of a fixture and the drain line. They are usually mounted on one leg of a sanitary tee, with the other leg going to the drain. The unit must be placed in accordance with local codes and the manufacturer's instructions.

pipe with air admittance valve
Step 3

Install PVC Drain Line

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.

pipe with air admittance valve
Step 4

Attach Air Admittance Valve

Depending on the type of fitting, glue or screw the AAV in place. Look to manufacturer's directions if you need additional assistance. 

pipe with air admittance valve
Step 5

Check Work

Depending on local codes and the AAV model, the completed installation should look something like this. AAVs must always be installed vertically and should be unobstructed from items under the sink. 

Comments (2)

How difficult was this project?
July 25, 2019
Difficulty: Very Hard
studor valve leaks
October 9, 2018
It didn't stop the gurgling at all. I placed it 10" above and straight up from the drain pipe in the floor with the P-trap coming in from the side of the T and water came out the top of it. Not sure what else to do.

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