Furnace maintenance. Single visit Dayton Maintenance. Verify operation, check 20x25x4 filter, check static pressures on ductwork Return-.41inwc Supply-.32inwc, check temperature rise across system 70-115, check inducer motor amp draw .53A, check indoor fan motor amp draw-5.6A, check combustion balance CO-8PPM O2-10.9%, check and clear all Venturi tubes and Venturi ports, check flame throw into heat exchanger, check heat exchanger condition, check and polish flame sensor, check hot surface ignitor, check drain connections, verify operation of drain connections after reconnecting, clear all drain tubes and drain ports, check flu connections, check gas connections, check fan board for wear or abnormalities, check blower compartment and and burner compartment and wipe down, reinstall all items and verify operation before leaving. Suggestions: The furnace is now 20 years old. The homeowners should plan for a replacement furnace and air conditioner if wishing for a warranty or guarantee