Brahma Immersion temperature sensor 18200499

This is an immersion temperature sensor from Brahma, type designation ST09 FE M/1 G1/8 CH15 (SKU 18200499). It is an NTC sensor that measures the temperature of the heat transfer fluid in heating and water heating equipment. The sensor reports temperature readings to the control board, enabling modulation and overheating protection. It has a G1/8 connection, version ch15, and dimensions of 40 x 20 x 15 mm. Net weight is 0.012 kg, gross weight 0.017 kg.

Replacement immersion NTC sensors are selected by their resistance characteristic at a reference temperature (typically 10 kΩ or 12 kΩ at 25 °C), probe form, cable length, and connector type. The probe form must match the installation point: immersion probes need a correctly sized pocket, while clamp-on probes require good thermal contact with the pipe. Before ordering, verify the electrical characteristic and mechanical fit against the existing part. For sensors that act on a switching point, the reset type (auto or manual) must also be considered.

Common failure modes for NTC temperature sensors include a drifting resistance characteristic, which causes incorrect modulation, a broken cable, or poor contact between a clamp-on probe and the pipe surface. When a sensor fails, the boiler may modulate incorrectly, fail to reach setpoint, or show erroneous temperature readings. Check the resistance at the reference temperature and inspect the cable and mounting for physical damage or poor contact.