A ___________ is a compartment or chamber to which one or more ducts are connected and that forms part of the air distribution system.

The term that fits the definition given is "plenum." A plenum serves as a crucial component of an air distribution system, acting as a central chamber where air is either supplied or returned. It connects with ducts, allowing for the effective movement of conditioned air throughout a building. The plenum is typically situated between the air handler or furnace and the supply ducts, facilitating the distribution of air to different zones or rooms within a structure.

Understanding the role of a plenum is vital, as it helps in maintaining airflow efficiency and balancing air pressure within the ventilation system. Properly designed plenums reduce turbulence and ensure an even distribution of air, which is essential for maintaining indoor air quality and comfort levels.

Other terms related to climate control systems, such as air handler, fan coil, and diffuser, serve different purposes. An air handler is responsible for circulating air, a fan coil is a type of heat exchanger that can warm or cool air, and a diffuser is a device that distributes air into a space from the ducts. While all these components play essential roles in HVAC systems, they do not describe a compartment or chamber like a plenum does.