Air filtration devices are typically located in which area?

The placement of air filtration devices is most effective when situated in the return air plenum. This location allows the filters to capture contaminants and particulate matter from the air being returned from various rooms before it is reconditioned by the heating or cooling system. By filtering the returning air first, the filtration system enhances the overall air quality within the building and protects the HVAC equipment from dust and debris, thereby improving efficiency and prolonging the lifespan of the system.

The other choices refer to areas where filtration may not be as effective. For example, while the fresh air plenum deals with outside air that is brought in and may require some filtration, it is not the main area for most filtration systems. The supply air plenum is focused on distributing conditioned air, and the exhaust air plenum is designed to remove air from the space rather than filter it. Thus, placing filters in the return air plenum is the most strategic choice for optimizing air quality and system performance.