Features: The products are used in solar water heater, the temperature difference and temperature to control the output. It is provided with two output control, temperature difference control two temperature zone. When the temperature reaches the set value, it automatically runs the water pump circulation and makes the two temperature zone temperature equilibrium. The other channel controls electric heating, when the solar heating failed to reach the set temperature, the electric heating system can automatically start and heat to the set temperature. It will control heating system and automatically makes water temperature stay in temperature deference range. Specifications: Power Consumption: ≤3W Heating Control Range: 2℃~99℃ Temp. Difference Start Control: 3℃~50℃ Resolution: 1℃ Precision: ±1℃ Input Signal: 2-channel sensor, 20KX2MX2 Size: 76*76*35mm/2.99*2.99*1.37in Operating Temperature: -10℃~50℃ Operating Humidity: RH≤90% Light Function Setting Range Default Unit #1 temperature difference start stop pump temperature difference +1~50 5 ℃ #1, #2 stop pump temperature difference 1~temperature difference start-1 2 ℃ #2 temperature return difference 1~20 5 ℃ #3 high temperature correction -10~10 0 ℃ #4 low temperature correction -10~10 0 ℃ Package Includes: 1 x Temperature Controller 2 x Sensor Probes .