Heating maintenance and safety inspection. Tested all mechanical components. Cleaned all sensors. Tested gas valve voltage and inlet/outlet pressures. Replaced the furnace filter that the customer provided. The system is clean, heating, and operating properly at this time. Performed a free plumbing inspection. Renew the annual VIP service plan. Sent estimate on new high-efficiency furnace and whole-home humidifier. Furnace is 23 years old.