This 2-position (open/close) control actuators is used with VCZ1000, 1100, 6000 and 6100 series hydronic valves in a normal indoor enviroment to provide quick opening/closing to control the flow of hot and/or chilled water or glycol solution to 60% concentration. They are designed for on-off "zone" control of heating/cooling systems, or to control individual fan coil, baseboard radiator or convertor applications.