
The differential thermostat is an electronic device that constantly monitors and compares the temperature of the water in the collectors and the temperature of the water in the boiler. When it finds that the water in the collectors is hotter than that in the boiler to some degree that we adjust it instructs the circulator to start and transfer hot masses of water from the collectors to the boiler exchanger by depositing the transferred thermal energy in the waste water. Many differential thermostats have the ability to command another source to heat the boiler water such as a boiler or electric resistor.