What is an example of a terminal device in HVAC systems?

A mixing box serves as an example of a terminal device in HVAC systems because it is specifically designed to facilitate the mixing of different air streams, typically from various zones or sources, to achieve the desired temperature and quality of airflow before it is delivered to the occupied space. This device plays a critical role in the overall control of indoor environmental conditions by allowing for the regulation of air temperature and ensuring it meets the needs of the space being conditioned.

In contrast, ductwork acts as a pathway for air distribution but does not actively participate in the mixing process. A fan, which is responsible for moving air through the system, functions upstream of the terminal devices, and while it is essential for air circulation, it does not qualify as a terminal device itself. Similarly, a heat exchanger, which transfers heat between two fluids, may be integral to the heating and cooling processes, but it does not directly interact with the final conditioned air supplied to occupied spaces. Thus, the mixing box is the most appropriate example of a terminal device in HVAC systems.