What is the normal return air requirement for a forced air furnace?

The normal return air requirement for a forced air furnace typically falls around 900 cubic feet per minute (cfm) for standard residential applications. This figure is based on the need to effectively recycle and distribute the air heated by the furnace back into the living spaces. By ensuring that there is adequate return air, the furnace can maintain efficient heating, avoid excessive cycling, and maintain consistent temperature throughout the home.

It's important to note that the specific return air requirement can vary based on the size of the home, the capacity of the furnace, and the overall heating load calculation. However, the figure of 900 cfm serves as a common benchmark used in various heating system designs to ensure proper airflow and efficiency. This ensures that the system is able to deliver heated air adequately throughout the space while also allowing for optimal performance and comfort.