How a Furnace Works: Airflow Diagram Explained #114860 (License: Personal Use)

Cold air enters the system through a return duct (left), passes over the heat exchanger where it’s warmed by combustion gases, and is then blown by a blower fan into supply ducts. Arrows indicate directional flow, with exhaust gases vented upward, ensuring safe operation and efficient heating.

Used on HVAC educational pages, homeowner guides, or contractor websites to explain furnace functionality; matches user intent for learning how heating systems work or troubleshooting airflow issues.