Preventative maintenence inspection on Lennox standard efficiency furnace running in good condition. 16x25x1 air filter in decent condition. Check again in 1-2 months. Clean flame sensor and check ignitor. Visual inspection of burners. Helen mentioned a noise when starting up. Duringntest run, nothing unusual was heard. Noise that is being heard is the exhaust motor and is operating normally. Test ran in heating mode from thermostat. Temperature rise is within specs. Blower and inducer motors tested good. Galvanized B-vent is in good condition with no sign of leaks. 0PPM CO detected during testing. System is operating properly, efficiently and ready for Winter.