“Stella” – the intelligent autonomous electrothermal actuator 230 VAC NC for the automatic adaptive hydraulic compensation of the heating circuits of a heating circuit distributor in panel heating and panel cooling systems. Sensors on the supply and return lines measure temperature differences and an algorithm continuously calculates the required temperature spread and the corresponding valve position. Closed when de-energized and with folding lever for unloaded unscrewing or for de-energized manual opening of the thermostatic valve. With integrated flow temperature limitation. Stella can be used in combination with all common temperature controllers and terminal strips (except devices with triac switching element).