How to Replace a Plumbing Vent

Plumbing vents that are exposed above the roof can be replaced.

Plumbing systems with replaceable vents consist of a removable air admittance vent that is connected to the P-trap under the sink or other fixture. These vents allow air to enter the plumbing system. Without a source of fresh air, plumbing drains would contain negative air pressure and constantly clog up. Replacing a damaged or old air vent requires removing the old unit, sealing the pipe threads and installing a new vent.

Things You'll Need

• Flashlight or work light
• Adjustable pliers
• Plumber's tape or pipe dope
• Replacement air admittance vent

Instructions

1. Place a flashlight or work light under the sink or other area where the air admittance vent is located.

2. Make sure the water is not running in the sink or other fixture being worked on. It is not necessary to shut off the main water, however.

3. Grab the existing air admittance vent with both hands and turn it counterclockwise until it pulls free from the P-trap. It may be necessary to use a pair of adjustable pliers to grasp the vent.

4. Wrap the exposed male pipe threads on the base of the new air admittance vent with a layer of plumber's tape or pipe dope. This will lubricate the threads and make for a watertight seal.

5. Place the new air vent into the P-trap opening and turn it by hand until tight.

6. Run the water in the sink or other fixture for two minutes to check the vent's installation. Listen near the vent for a slight rushing of air. If the vent is not allowing air into the system, tighten it further with the pliers.