Furnace clean and tune. Cycled system. Checked heat exchanger, found a few spots of concern. One spot has a deep etch that is cracking. Failure of heat exchanger will occur in that spot in the near future. Checked for CO in airstream, none found. Normal levels of CO and XS air found in exhaust. Igniter flame rod assembly is weak and worn. This system is 15 years old. Average lifespan of this unit is 14 years. With that crack forming in heat exchanger, failure is expected. Due to age, condition, and cost to repair, second opinion is recommended. Call peters cell to schedule. Office to bill for job. Job complete.