The thermistor decreases current resistance as the temperature of the thermistor rises. The printed circuit board sends a current to the thermistor and can tell whether a decrease or increase in heat is needed by the relative resistance in the thermistor.
Genuine replacement part for Potterton
Supplier Part Number 404516
Technical specification
Waist Sizeaa45ch57gxSupplier Part Number404516Brand NamePotterton