Performed annual tune-up on a Crown propane boiler. Cleaned the burners, heat exchanger, igniter, flame sensor, and pilot assembly. Inspected safety controls, relief valve, expansion tank, venting, and overall hydronic system function. Bubble-tested the gasline, pilot line and checked carbon monoxide levels—no leaks detected. Flushed sediment from an indirect water heater. They don’t think the noise that they’ve been hearing is related to the heating system. Verified proper operation; the system is functioning correctly at this time.