Furnace clean and tune. Cycled system. Checked heat exchanger, found all chambers to be rusted and corroded. No visible cracks found with camera. Deep etching and rust found. Checked, removed, and cleaned burners and flame sensor, both ok. Checked and tightened electrical connections and clamps. Cleared drain lines. Found rusting and evidence of water leak from transition assembly. Preformed combustion test and found normal levels is exhaust. No CO found in airstream. Average life expectancy for this unit is 14 years. This unit is showing signs of getting worn. Due to age, condition, and cost of repair, second opinion is recommended. System operating normal at this time, but future failure is expected. Removed old heat register and installed new. Fireplace clean and tune. Cycled fireplace. Ok. Cleaned glass. Cleaned walls, logs, ignition system, and under unit. Cleaned ignition system as best as I could. It is very hard to reach due to its placement to the manifold. System operating