I just finished conducting the annual maintenance service on a Rinnai tankless water heater for one of my clients. I began by flushing the heat exchanger to remove any mineral buildup, using a commercial descaling solution. I also inspected and cleaned the unit's air intake and exhaust vents to ensure proper airflow. Additionally, I tested the temperature and pressure relief valve to confirm it was operating correctly. Finally, I checked all electrical connections and the overall system performance to verify the tankless heater is running safely and efficiently for the homeowner.