The automatic filling valve is a device consisting of a pressure reducing valve with compensating seat, visual system pressure setting indicator, an inlet filter, anti-scale internal parts, a shut-off valve (round knob on bottom) 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 at a set value, automatically filling up with water as required. The valve is pre-adjustable, meaning it can be set to the desired pressure value before the system charging phase. After installation, during the filling or topping-off phase, the water feed will stop when the set pressure is reached. This valve fills 50% faster than other valves. There are no levers to flip or valve to close. Pre-assembled with the 573 series backflow preventer, the AutoFill™ Combo features an atmospheric vent which is designed to protect drinking water systems from return flow, caused by back-siphoning or back pressure, of contaminated fluids. The 573 series has been specifically certified to standards CSA B64.3 and ASSE 1012.