Electromotoric actuators to operate Siemens 2-port and 3-port valves, types V..F21.., V..F22.., V..F31.., V..F32.., V..F40.., V..F41.., V..F42.., V..F52.., and V..F53.. with 20 mm stroke as control and safety shut-off valves in heating, ventilation and air conditioning systems.