Preventative maintenence inspection on Tempstar gas furnace running in good condition. 20x25x4 air filter replaced today. Clean flame sensor and check ignitor ohms. Flush condensation trap and drain lines. Run test unit in heating mode from thermostat. 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. System is operating properly, efficiently and ready for Winter.