Product Information: The thermistor increases the current resistance as it gets colder The PCB sends a current to the thermistor and can tell whether a decrease or increase in heat is needed by the relative resistance provided by the thermistor.
This part is present in 4 different boilers in the Saunier Duval range including the Saunier Duval THEMAPLUS F 23 E , THEMA F 23 E , COMBITEK F 23 E , THEMACLASSIC F 30 E .