Preventative maintenence inspection on Carrier high efficiency gas furnace running in great condition. 20x25x4 air filter in good condition. #35 humidifier pad in new condition. Clean flame sensor and check ignitor. Visual inspection of burners. Flush condensation trap and drain lines. Run test unit in gas heating mode. Temperature rise is within specs. Blower and inducer motors tested good. Pvc flue vents in good condition and no sign of leaks. 0PPM CO detected during testing. Humidifier tested for proper operation. Checked geothermal heating and erased codes stored in system. Only codes present are normal operation codes for hot water generation and system resets. No issues found or suspected with gas furnace, geothermal unit, and humidifier. Due to high a,outstanding of dust and frequent filter changes being required, it is recommended to have the ducts cleaned. Since ducts have not been cleaned and system was operational during construction, there is most likely an excessive amou