Grilles, registers, and diffusers are categorized as what type of devices?

Grilles, registers, and diffusers are categorized as terminal devices because they are specifically designed to manage the delivery and distribution of conditioned air within a space. Their primary function is to interface with the ductwork and direct airflow into the occupied areas.

Terminal devices differ from flow regulators, which are used to measure or control the flow of air but do not directly handle the distribution. Control devices are typically used for regulating or adjusting the environmental conditions, such as thermostats or valves. Distribution devices, while related, generally refer to larger components in the air distribution system and might include ductwork itself. Terminal devices, therefore, serve a crucial role by ensuring that air is effectively delivered into the room in a way that optimizes comfort and efficiency.