Vokera thermistors decrease circuit resistance in line with temperature increases. A boiler's printed control board (PCB) sends a current to the thermistor, deciding whether a decrease or increase in heat is required by reading the relative resistance.
Dry sensor
Clips on to the pipe
Technical specification
Waist Sizeaa54cf57guTypeSensorERP RatingNot ApplicableSupplier Part Number20081926Brand NameVokera
Reviews
Vokera Negative Temperature Coefficient Dry Sensor 20081926.