The thermoelectric actuators are used to open and close valves in heating, air conditioning and ventilation systems. They are available in 230 V and 24 V versions with a plug-in connection cable (1m) in a splash-proof housing with stroke indicator. The actuators are preferably used for individual room temperature control to control radiators, convectors and cooling ceilings. The electronic switching actuator ES/S or the electronic relay ER/U in conjunction with the universal interface US/U and a room temperature controller are suitable for control (2-point control or pulse width modulation). The plug-in installation on valves and heating circuit distributors is carried out using the valve adapter VA/Z XX.1.