The Vent-and-Purge Assembly allows purging of the zone at the manifold location. The Vent-and-Purge Assembly consists of a 1-1/2 in. BSP sleeve nut for attaching to the end of the manifold, and a 3/8 in. manual air vent valve. Also includes a 1/2 in. hose fitting with a built-in ball valve to allow zone draining and filling. Nickel-plated brass. Sold individually.