What Is Air Admittance Valve?

What Is Air Admittance Valve?

What Is Air Admittance Valve?

An air admittance valve (AAV) is a device that allows air to enter the drainage system in order to balance pressure and prevent water from being siphoned out of the trap when negative pressure develops in the system.

It is used on individual vents, branch vents, and circuit vents instead of vents that lead to the outside of a building.

Stack vents and vent stacks are allowed to connect to a stack-type AAV, except for those that serve drainage stacks with more than six branch intervals.

How Is Air Admittance Valve Installed?

An air admittance valve (AAV) is a device that can be installed to allow for new vent lines in a plumbing remodel when structural elements block access to the existing drain-waste-vent system.

AAVs work by responding to the negative pressure created by draining water and opening to allow air in, then closing to keep sewer gases out of the room.

To install an AAV, it is important to understand how they work, determine the proper placement, install the PVC drain line, attach the AAV, and check the work to ensure compliance with local codes and the manufacturer’s instructions.

It is important to note that local codes govern the use of AAVs in place of vents, and it is recommended to check with the local building inspection office before installing.

How To Tell If Air Admittance Valve Is Working?

To determine the functionality of an air admittance valve, you can conduct the following tests:

  • Listen for a hissing sound coming from the valve, if you hear it, the valve is working.
  • Check for water leaks, if there are any, the valve is not working.
  • Attempt to open and close the valve, if it is functioning, it should move easily.
  • If there is no water or air coming out of the valve, it may be clogged and need replacement.

How High Should An Air Admittance Valve Be Installed?

The AAV must be placed at least 6 inches above the highest fixture and within the maximum length for the vent. It should be easily accessible for replacement, with air able to enter the valve.

It should also be installed at least 6 inches above insulation that could block the air inlets.

The installation must follow the guidelines of the IPC and IRC, and if there are conflicting instructions, the stricter guidelines must be followed.

Are There Any Issues To Consider When Using An Air Admittance Valve?

The main concern with an Air Admittance Valve (AAV) is the potential for the product to fail and stop functioning, allowing unpleasant odours into the home.

To avoid this, it is recommended to install the AAV in an easily accessible area, and to choose a high-quality, well-known brand.

If the valve is malfunctioning, it may be possible to fix it by inspecting the rubber seal and applying pipe lubricant.

In case of a blockage in the waste pipe, it may be necessary to call a local drainage engineer for assistance.

Additionally, the AAV should be installed in the correct location, such as above other water entry points in the system, to ensure proper functioning.

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