What is a defining feature of an All-Air Constant Volume system?

The defining feature of an All-Air Constant Volume system is that it operates with a single duct system that maintains a constant airflow throughout the system. This means that the amount of air being delivered to the conditioned space does not vary, regardless of the changes in load conditions or temperature. Such a system helps maintain a uniform temperature and air quality but relies on adjusting the temperature of the air being supplied, typically by heating or cooling it as needed.

In contrast, variable air volume systems adjust the airflow based on the demand within the space, which is not characteristic of a constant volume system. Multi-zone control implies multiple zones with separate temperature controls, which may not be a feature of a single duct constant volume system. Additionally, while multiple air conditioning units can be present in some systems, it is not a defining feature of an All-Air Constant Volume system, which is more concerned with airflow consistency rather than the quantity of units.