Responded to call for RS12-4 condensing boiler (LP, 4 years old) displaying overheating code and shutting down after only 10 seconds of operation. Inspection revealed blocked combustion air intake with debris and a bumblebee obstructing proper airflow. Preliminary diagnosis indicates possible scaling on heat exchanger per manufacturer's technical information. Unit was powered off for safety as heat exchanger temperature was excessively high. Return visit scheduled to perform full diagnosis with manufacturer technical support and determine if descaling procedure is required to restore proper operation.
