Siemens Flame sensor QRB1B-A014U25B

The Siemens QRB1B-A014U25B is a flame sensor (photodetector) used for photoelectric flame monitoring in oil-fired burners. It is designed for diesel fuel and heavy oil applications in boilers, heat generators, and burner devices. The sensor detects light emission from the flame and transmits a signal to the burner control. In the event of flame loss, it triggers an emergency fuel shut-off. The device has a compact design and is made of heat-resistant plastic, and it is compatible with Siemens LOA and LMO series controls.

Parts of this type are selected by detection principle—UV, IR, or ionization—and by spectral range, response time, cable length, connector type, and mounting sleeve. When replacing a flame sensor, match the replacement to the original in sensing range and mounting. The viewing window must be clean and free of contamination. Mounting forms include direct integration into the burner housing, aimed at the flame.

Typical failures include a contaminated window, a weakened signal from an aged cell, or a broken sheath. When a flame sensor fails or loses sensitivity, the burner control may not receive a valid flame signal. Within the safety time, the control will then lock out and shut the burner down to prevent unsafe operation.