913.1 General. Vent systems utilizing Air Admittance Valves (AAV) shall comply with this section. Individual and branch-type air admittance valves shall conform to ASSE 1051.
913.2 Installation. The valves shall be installed in accordance with the requirements of this section and the manufacturer's instructions. Air admittance valves shall be installed after the required DWV testing has been performed.
913.3 Permitted Use. The use of AAVs shall be limited to the following circumstances:
913.3.1. Island Fixtures. Where a group of sinks and drains, not exceeding a total of 4 drainage fixture units, are remote from a wall extending to the ceiling.
913.3.2. Where a group of fixtures, not exceeding a total of 4 drainage fixture units, is more than a 30-foot horizontal radius from another plumbing fixture or plumbing vent of adequate size.
913.3.3. Additional locations when submitted and approved by the AHJ by submitting a "Request for Alternate Design, Materials, or Methods of Construction".
913.4 Where Permitted. Individual and branch-type air admittance valves shall vent only fixtures that are on the same floor level and connect to a horizontal branch drain. Where the horizontal branch drain is located more than four stories below the top of a waste stack, the horizontal branch shall be provided with a relief vent that shall connect to a vent or extend outdoors to the open air. The relief vent shall connect to the horizontal branch drain between the waste stack and the most downstream fixture drain connected to the horizontal branch drain. The relief vent shall be sized in accordance with Section 904 and installed in accordance with Section 905. The relief vent shall be permitted to serve as the vent for other fixtures.
913.5 Location. Individual and branch-type air admittance valves shall be located not less than 4 inches above the horizontal branch drain or fixture drain being vented. The air admittance valve shall be located within the maximum developed length permitted for the vent. The air admittance valve shall be installed not less than 6 inches above insulation materials.
913.6 Access and Ventilation. Access shall be provided to all air admittance valves. Such valves shall be installed in a location that allows adequate volumes of air to enter the valve. AAVs installed in interior walls shall be provided with a removable grille/louver that is of adequate size to replace the valve through the opening.
913.7 Size. The air admittance valve shall be rated in accordance with the standard for the size of the vent to which the valve is connected and per the manufacturer's recommended sizing guidelines.
913.8 Vent Required. Within each plumbing system, not less than one vent shall extend through the roof in accordance with Chapter 9.
913.9 Prohibited Installations. Air admittance valves shall not be installed in non-neutralized chemical waste systems as described in Chapter 8. Air admittance valves shall not be located in spaces utilized as supply or return air plenums. Air admittance valves shall not be used to vent sumps or tanks except where the vent system for the sump or tank has been designed by an engineer. Air admittance valves shall not be installed on outdoor vent terminals for the sole purpose of reducing clearances to gravity air intakes or mechanical air intakes. Air admittance valves shall not be installed in cold attics, exterior walls, or where exposed to freezing temperatures. Air admittance valves shall not be installed within fire rated assemblies. Air admittance valves shall not be installed to vent water closets.
(AO No. 2021-88(S), § 12, 2-15-2022)