The Homematic IP radiator thermostat compact actively helps save energy within the Homematic IP smart home system. The tamper-proof controller replaces existing radiator thermostats and allows for energy savings of up to 30% through demand-based heating. The radiator thermostat is easily mounted onto valves with an M30 thread using the metal nut. No intervention in the heating system or draining of water is required. The compact thermostat is operated exclusively via the free app or an additional wall thermostat, making it particularly suitable for offices, small businesses, children's rooms, or tight niches. The included dismantling protection and the closed housing prevent unauthorized tampering and theft. Two AA batteries power the thermostat for up to 5 years. After installation, up to three heating profiles with a maximum of six heating phases per day can be defined at room level via the app – ensuring that the office is already warmed up upon arrival in the morning, while valuable energy is saved after working hours. Of course, the room temperature can also be manually adjusted via the app, a Homematic IP wall thermostat, or conveniently by voice command. The system becomes truly smart when combined with a Homematic IP window and door contact. If it detects an open window, the radiator thermostat shuts off the hot water supply to the radiator. When the window is closed again, the radiator resumes its operation. This helps save energy, increases living comfort, and protects the environment. The built-in lime and frost protection automation prevents the valve from calcifying and freezing.