The Ontario Building Code | Installation Conditions
220.127.116.11. installation Conditions
(1) Air admittance valves shall not be installed in supply or return air plenums, or in locations where they may be exposed to freezing temperatures.
(2) Air admittance valves shall be installed in accordance with the manufacturer’s installation instructions.
(4) Installed air admittance valves shall be,
(a) accessible, and
(b) located in a space that allows air to enter the valve.
Section 7.6. Potable water Systems
7.6.1. Arrangement of Piping