How Do Air Admittance Valves Work?
Learn the basics of air admittance valves (AAVs), including how they work and when it is best to install one in your home.
What is an Air Admittance Valve?
Air Admittance Valves — also called cheater valves, mechanical vents, and even durgo valves — are mechanical devices that provide you with a one-way venting system. They allow air to enter your drain as the water disappears.
Venting is an essential requirement for every plumbing system. An AAV simply takes the place of a traditional vent used by many homes. Advantages of using an AAV over a traditional or classic vent include:
- You won’t need to place holes in your roof or walls to install them
- They reduce the labor needed on pipes to fit onto a ventilating stack
Why are Air Admittance Valves Necessary?
Unless you want sewer gases entering your home when your plumbing is under positive pressure, you’ll want a venting system. And AAVs are mechanical devices that can accomplish the task easily.
Likewise, they equalize the air pressure in your pipe, which allows them to drain properly and prevent those sewer gases from getting into your living space.
Here’s How Air Admittance Valves Work
AAVs work with the help of a rubber sealing mechanism that is lifted to let air into the drain system. Positive pressure causes the mechanism to close so that gases cannot escape into the home.
Most homes vent directly through an opening on the roof of their house. Sometimes structural blockages or multi-stories won’t allow a vent to be placed on the roofline. In those cases, air admittance valves are another option to consider.
Where Can AAVs be Installed?
For the most part, air admittance valves are placed between the P-trap of a fixture and the drain line. They usually mount on one branch of a sanitary tee, with the other branch going to the drain. This must be all done according to your local codes and the instructions by the maker.
PRO TIP: A sanitary tee (a type of plumbing tee) is literally a T-shaped pipe with two outlets, hence the name. They design them to connect a branch line into a vertical drain (or vent) line.
Does Your System Need an Air Admittance Valve?
Typically, noisy, gargling sinks and slow draining toilets are good indicators that your home needs an improved venting system. AAVs can greatly reduce the number of venting materials in a plumbing system and are generally maintenance-free.
Moreover, most plumbers recommend this kind of mechanical venting system for kitchen islands, when there is a large window above a sink or wherever a traditional vent would be problematic.
Final Thoughts
Overall, if you believe the vents in your home does not work as it should, we strongly recommend calling a plumber to at least assess the situation. Smelly, toxic gases in the home are no laughing matter.
And if you’re up to the challenge and have the skill level required, you could try installing an AAV yourself.
In addition, before installing an air admittance valve to your plumbing system, check with your local building department to ensure using an AAV in your home is up to code. Here is the plumbing code for Ohio.
Call 1-Tom-Plumber
If you’d like 1-Tom-Plumber to repair or replace an Air Admittance Valve that’s up to code in your home, don’t hesitate to contact us or call us at 1-Tom-Plumber (1-866-758-6237).
We immediately respond to and handle any emergency plumbing, drain cleaning, and water damage problem, including excavation of underground water lines and sewer main lines.
