Honeywell Servomotor B2-5S3 LKS131-03

The Honeywell B2-5S3 LKS131-03 is a servomotor actuator designed for installation on multistage or modulating diesel burners, operating in a fully closed position. It is powered by a 200–240 V supply, consumes 9 W, and opens a 90-degree air flap in 5 seconds. The actuator delivers a torque of 60 Nm and features a reversible synchronous motor with a maintenance-free cylindrical gear transmission. It has a standard plastic output shaft with an inner square of 8 mm, weighs 500 g, and measures 10x6x8.5 cm. The unit is protected to IP40 and complies with EU directives 73/23/EU and 93/68/EU.

When selecting a replacement actuator of this type, ensure the supply voltage, torque, and opening time match the burner's requirements. The output shaft type and size (e.g., inner square 8 mm) must be compatible with the existing linkage. Mounting is typically from the inside using through holes with M5 thread; verify the mounting hole pattern and dimensions. The actuator's connection system (e.g., fixed cable with 9-pin connector) must match the burner's wiring. Always compare the physical dimensions to ensure clearance within the burner housing.

Common failures of such actuators include motor burnout due to overloading or voltage spikes, resulting in the flap not moving or moving slowly. Gear wear can cause backlash, leading to inaccurate positioning or erratic operation. Limit switch failures may prevent the actuator from stopping at the correct open or closed position, causing the burner to run inefficiently or shut down. Check for unusual noises, excessive heat, or visible damage to the shaft or cams. Verify the electrical connections and measure the motor's resistance to diagnose issues.