Working for our client in Reynoldsburg, OH, I performed yearly maintenance and safety checks on a 14-year-old Bryant furnace. I cycled the heat and recorded 6.9% O₂, 47 ppm CO in the flue, and 0 ppm CO in the supply, with a 47-degree Delta T. I replaced the 16x25x1 air filter, measured the ignition at 47 ohms, and cleaned the flame sensor and flue trap. No issues were identified during this inspection.