An Air Admittance Valve (AAV), which you may also hear referred to as a Studor Vent, Studor AAV or Mini Vent, is a one-way mechanical valve that is installed locally at the site of a plumbing fixture, allowing proper venting to occur without a connection to a larger venting system and stack vent.

Air admittance valves are approved by the International Residential Code (IRC), which is used in most areas of the country with only minor modifications, but not code approved in a few jurisdictions. One is shown above, and they are designed to open and admit air into a sink drain line when there is negative pressure (suction) in the pipe, which allows the drain to flow freely without gurgling for air. The one-way vent only allows air into the system for drainage, then closes to keep sewer gas from escaping out into a home. When the location of a plumbing fixture makes it difficult to run a regular (passive) vent pipe through the roof this type of vent is an alternative solution.

There is also a similar, but older, system that is spring-loaded and allowed in mobile/manufactured homes under the jurisdiction of HUD, but not site-built homes. It is shown below and correctly called a mechanical vent, auto vent, in-line vent, or check vent. The air admittance valve design utilizes a rubber-like membrane that flexes to allow air into the drain system. It is sometimes referred to by the acronym AAV. The Studor Corporation is the largest manufacturer of AAVs, so they are often referred to as Studor® vents or Studor® valves.

Two requirements for correctly installing an AAV are that it must a minimum of 4” above the fixture drain and readily accessible. Although they are rated for a minimum of 500,000 open-and-close cycles, which is approximately 30 years of usage, they do fail eventually and, occasionally, prematurely; so it’s important to be able to get to the AAV to change it out. They have a screw fitting, so switching out a dead air admittance valve is an easy plumbing chore.

Air admittance valves can also be installed in an attic, but must be 6-inches or more above the insulation. Because an AAV requires negative pressure to open, it cannot be installed to vent a sump pump, which generates positive air pressure when operating. Also, a home’s plumbing drainage cannot rely entirely on AAVs; a minimum of one vent through the roof is required by the building code.

A common problem in plumbing remodeling is how to run new vent lines when a structural element blocks access to the existing drain-waste-vent system. It might seem like all hope is lost, but don't let that minor 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.

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 unreliable and don't meet code in most areas.

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

Install the PVC drain line, the sanitary tee, and the P-trap for the 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.

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

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

The completion of the studor vents installation in a house is like the final brushstroke on a masterpiece. With expert precision, the plumbing professionals skillfully integrate the versatile AAVs (Air Admittance Valves) into the intricate network of pipes and drains. The house, amidst an ongoing renovation project, eagerly awaits the arrival of these innovative Studor Vents, which will revolutionize its plumbing system. As the installation is meticulously carried out, one can almost hear the symphony of pipes harmonizing with the gentle hum of the AAVs, creating a melodious rhythm that ensures the smooth flow of wastewater and air throughout the house.

In the realm of plumbing, the installation of Studor Vents is an essential milestone in any renovation project. With the precision of a surgeon, the professionals carefully position the AAVs in strategic locations, breathing new life into the plumbing system. These ingenious devices, known for their reliability and efficiency, seamlessly integrate into the existing infrastructure of the house, ensuring the swift removal of wastewater and the proper ventilation of air. As the final Studor Vent is secured in place, the house seems to exhale a sigh of relief, embracing its newfound functionality and efficiency. The completion of the studor vents installation is not merely a technical achievement, but a testament to the dedication and expertise of the plumbing professionals who have transformed a house into a haven of comfort and convenience.