Thermostatic Radiator Valves (TR-01) sense the air temperature around them and regulate the flow of water through the radiator which they are fitted to. They do not control the boiler. They should be set at a level that gives you the room temperature you want. These settings may have to be different in each room, and you should set the TRVs to suit each room and then leave them to do their job. Turning a TRV to a higher setting will not make the room heat up any faster. How quickly the room heats up depends on the boiler size and setting, and the radiator size. Turning a TRV to a lower setting will result in the room being controlled at a lower temperature, and saves energy. TRVs need a free flow of air to sense the temperature so they must not be covered by curtains or blocked by furniture. Etop Thermostatic Radiator Valve Features: Thermostat operating voltage: 2 x AA1.5 V, alkaline batteries. Backup storage: EEPROM Frequency: 433/868Mhz Switching options: 7 days programming (4 periods/day) Temperature settings: 5°C ~ 35°C, in 0.5℃ Accuracy:± 0.5℃ Control: PID Thermostat dimensions:φ55*69mm            Color: White IP protection rating: 20. Certificate:CE, ROHS, RED   OEM, ODM is our main service. Help end user save energy but create them comfortable living temperature; Provide our customer solution to help you be more professional.