How does the amount of return air taken from a room relate to the flow rate of supply air?

The relationship between the return air amount taken from a room and the flow rate of supply air is governed by fundamental HVAC principles. In a balanced air distribution system, the volume of return air should not exceed the volume of supply air. This ensures that the system operates efficiently and maintains appropriate pressure levels within the space. If the return air were to exceed the supply air, it would create a vacuum effect, potentially leading to airflow issues, drafts, and inefficiencies.

Moreover, maintaining this balance is essential for effective heating, ventilation, and air conditioning processes. It ensures that the air circulation is consistent, which aids in temperature regulation and air quality management. Overall, controlling the amount of return air relative to the supply air flow rate is critical for the designed performance of HVAC systems. Thus, stating that the amount of return air must not be greater than the amount of supply air aligns with these principles of air balance and efficiency within a mechanical system.