Air Admittance Valve Under Sink

An air admittance valve (AAV) is a one-way valve that allows air to enter a drainpipe when needed to prevent the formation of a vacuum. This can occur when water is draining from a fixture and there is not enough air to replace it. A vacuum can cause the water to drain slowly or even stop altogether. AAVs are typically installed under sinks or in crawl spaces.

AAVs are designed to open when the pressure in the drainpipe drops below atmospheric pressure. This allows air to enter the pipe and equalize the pressure. The valve then closes when the pressure returns to normal. AAVs are not designed to allow water to flow back into the fixture.

AAVs are an important part of a plumbing system. They help to ensure that drains flow properly and prevent the formation of clogs. AAVs are relatively inexpensive and easy to install. They can be purchased at most hardware stores.

How to Install an Air Admittance Valve

Installing an AAV is a relatively simple process. The following steps will guide you through the installation:

Turn off the water supply to the fixture.
Disconnect the drainpipe from the fixture.
Clean the end of the drainpipe and the inside of the AAV.
Apply a bead of plumber's putty around the base of the AAV.
Screw the AAV onto the drainpipe.
Tighten the AAV until it is snug.
Reconnect the drainpipe to the fixture.
Turn on the water supply and check for leaks.

Troubleshooting AAVs

AAVs can sometimes malfunction. The following are some common problems and how to troubleshoot them:

The AAV is not opening. This can be caused by a build-up of debris on the valve. To clean the valve, remove it from the drainpipe and soak it in vinegar for a few hours. Then, rinse the valve with water and reinstall it.
The AAV is not closing. This can be caused by a damaged diaphragm. To replace the diaphragm, remove the AAV from the drainpipe and unscrew the top cap. Then, replace the diaphragm and reinstall the cap.
The AAV is leaking. This can be caused by a cracked housing or a loose connection. To fix the leak, tighten the connection or replace the housing.

If you are having trouble troubleshooting your AAV, you may need to call a plumber.