Performed boiler tune-up service on 20-year-old system after customer reported no heat to second floor radiators. Diagnosed airlock in system preventing proper circulation and critically low water pressure. Purged air from the system, restored water pressure to 18psi, verified proper radiator heating throughout the house, and confirmed normal system operation after checking burners, heat exchanger, flue, fresh air intake, pumps, relay controls, gas pressure, and combustion air.
