National HVAC replacement costs average $5,000 to $15,000 per system lifespan
https://precision-five-star-hvac.theburnward.com/balanced-airflow-extends-hvac-longevity-beyond-the-typical-15-to-20-year-window-1
Most residential HVAC systems last 15 to 20 years, but replacement decisions hinge on cost-data benchmarks rather than age alone