Performed furnace maintenance on 18-year-old Bryant heater. Upon my maintenance there were a couple points of concerns that were addressed with homeowner. 1. Found heat exchanger with very large hotspots all around burner cells. This has occurred due to an air restriction Within the duck work and it’s ultimately causing the heat exchanger to become hotter than what it is designed for. 2. Found that hot surface igniter was becoming higher in ohms and had contained many hotspots due to wear and tear 3. Flame sensor was beginning to form oxidization and may cause heating failure on start up 4. Home only contains one return intake and should have at least three to maximize Airflow and reduce overheating.