The products are used in solar water heater equipment, 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 run the pump circulation, make the two temperature zone temperature equilibrium is reached, electric heating control another way; when the solar heating failed to reach the set temperature, the electric heating system can automatically start the heating to the set temperature, temperature difference control and automatic  constant temperature in the range.