The Glow-worm thermistor works by decreasing current resistance in a manner that is inversely proportional to the temperature of the thermistor. The electronic control board sends a current to the thermistor and can tell whether more or less heat is needed.
Comes with clips attached
Technical specification
TypeThermistorToilet Cistern CapacityFTW--Supplier Part Number0020025235Brand NameVaillant
Reviews
Vaillant Glow-worm Thermistor Temperature Sensor 0020025235