Caleffi Series 553 Automatic Filling Units 1/2"Union NPT Male Inlet with 1/2" NPT Female Outlet

The AutoFill™ automatic filling valve is a pressure reducing valve with a compensating seat, an inlet filter, a shut-off valve and a check valve. It is installed on the water inlet piping in sealed heating systems, and its main function is to maintain the pressure of the system to a preset value, automatically filling up with water as required. This valve has been designed as pre-adjustable, which means it can be adjusted at the required pressure value before charging the system. After installation, during the filling or topping-off phase, the water feed will stop automatically when the set pressure is reached. There are no levers to flip or valve to close. Preassembled with the backflow preventer, it features an atmospheric vent which is designed to protect drinking water systems from return flow, caused by back-siphoning or backpressure, of contaminated fluids. The 573 series has been specifically certified to standards CSA B64.3 and ASSE 1012.