De Dietrich S103268 high limit sensor

This is a De Dietrich S103268 high limit sensor, listed under temperature NTC sensors in the catalogue. The part is identified by manufacturer codes S103268 and 336.220.011. As a high limit sensor, it belongs to the class of NTC (negative temperature coefficient) sensors used in boiler and burner systems to report temperature values to the control board. While standard NTC sensors continuously monitor flow, return, cylinder or outdoor temperatures for modulation, a high limit sensor acts as a safety device: it is typically set to trigger an alarm or interrupt the burner operation if the sensed temperature exceeds a preset threshold, preventing overheating. Parts of this type are selected primarily by their resistance characteristic (for example 10 kΩ or 12 kΩ at 25 °C), the probe form (immersion, clamp-on or sleeve), cable length and connector type. The mounting method must match the application – an immersion probe goes into a pocket, a clamp-on probe attaches to a pipe surface, a sleeve probe fits into a thermowell. When replacing a high limit sensor of this class, confirm that the resistance curve and the switching behaviour (if the sensor is used as a direct acting limit switch) are compatible with the control board’s input. Common failures are a drifting NTC characteristic that causes the boiler to modulate incorrectly, a broken cable, or poor thermal contact between a clamp-on probe and the pipe, which delays the response and can lead to unsafe conditions. Always verify the probe’s seating and cable integrity during replacement.