In a balanced air distribution system, the total supply CFM should be within what percentage of the total return CFM?

In a balanced air distribution system, the total supply CFM (cubic feet per minute) should ideally be within ±10% of the total return CFM to ensure efficient operation and proper air circulation. This balance is crucial because it helps maintain indoor air quality and comfort levels while also ensuring that the HVAC system operates efficiently.

Demands for heating or cooling require that the amount of air supplied be well-matched with the amount of air being returned to the system. If the supply air significantly exceeds or falls short of the return air, it can lead to issues such as pressure imbalances, inadequate temperature control, or increased system wear.

Achieving this balance allows for optimal airflow patterns, providing the comfort needed in conditioned spaces. A margin of ±10% is generally accepted as an industry standard for maintaining this balance, which helps to minimize complications like noise or drafts caused by improper air distribution.