Thermostatic actuators for controlling the room temperature. Setpoint adjustment with knob. Versions with shutoff and frost protection position. Limit stops for minimum and maximum values or setpoint locking. Mounts directly on Siemens radiator valves VDN../VEN../VUN../VPD../VPE..Adapter for third-party valves, see overview AV.. The radiator valves can be closed with the thermostatic actuators RTN51.. and RTN71..