2021 Carrier high efficiency furnace running in great condition. 20x25x4 air filter is new today. Clean flame sensor and check ignitor. Visual inspection of burners. Flush condensation trap and drain lines. 3" pvc flue in good condition and no sign of leaks. 0PPM CO detected during testing. Run test unit in heating mode. Delta t of 54F with supply temp of 121F, Delta t spec of 40-70F. System is operating properly, efficiently and ready for Winter.