Model No. 20391;The valve should be connected to the piping in accordance with the manufacturer’s installation instructions;The valve should be installed in the vertical, upright position after rough-in and pressure testing of the DWV system;A minimum of one vent shall extend to the open atmosphere for ever building drainage system;The valve should not be installed as a vent terminal for any special (chemical) waste system or in supply and return air plenums;For installation in areas with temperature range between –40 and 150 degrees F