In multi-level structures, how many separate returns must be installed on each level?

In multi-level structures, the requirement for separate return air ducts largely depends on ensuring proper airflow and system efficiency. Having one separate return on each level is often sufficient to facilitate effective air circulation throughout the space. This is because a single return duct can attract air from the entire level, allowing for balanced air pressure and temperature regulation.

When designing HVAC systems for multi-level buildings, it is essential to consider the distribution of conditioned air and how it affects occupant comfort as well as system performance. A single return at each level can help avoid dead zones where air does not circulate effectively. Additionally, having too many returns can create unbalanced air pressure, leading to inefficiencies in the heating and cooling process.

Thus, the choice of one separate return on each level aligns with industry practices for optimizing system functionality while maintaining comfort in the living or working environment.