Honeywell Temperature sensor T7335D1016B

This Honeywell type T7335D1016B temperature sensor is an NTC (negative temperature coefficient) device for boiler and burner control systems. It is intended for Ferroli Arena C, Arena F, Diva C, Diva F, and Domicompact D boilers. The sensor feeds a resistance signal that changes with temperature to the control board, allowing continuous proportional control. It supersedes part numbers 39810220 and 36200540.

Sensors of this general type are selected by matching the resistance characteristic at a reference temperature—commonly 10 kΩ or 12 kΩ at 25 °C—to the control board’s input specification. The probe form must fit the mounting point: immersion (directly in the water/pipe), clamp-on (attached to the outside of a pipe), or sleeve (inserted into a thermowell). The cable length and connector type must also match the original sensor. Before ordering, compare these parameters with the existing part and the boiler's wiring.

Failures of this kind typically appear as a drift in the resistance characteristic, leading to erratic temperature readings; a broken cable; or poor thermal contact when a clamp-on probe is used. The boiler may then modulate incorrectly, show an unexpected temperature, or trigger a fault code. Checking the resistance across the sensor and inspecting the cable and mounting surface will help identify the cause.