Which type of switch is utilized for detecting supply airflow?

The correct choice for detecting supply airflow is the flow switch. A flow switch is designed specifically to monitor the presence or absence of fluid movement, such as air or liquid, within a system. When airflow is detected, the flow switch will typically actuate or close a circuit, which can then signal further actions within the HVAC system, such as activating fans or triggering alarms if airflow is lost.

While pressure differential switches and other devices can indicate changes in flow conditions indirectly, the flow switch directly measures airflow and is most effective for this purpose. Pressure differential switches monitor the difference in pressure before and after a component to infer flow conditions, but they do not detect airflow directly. Current switches measure the electrical current running through a motor or other equipment to infer operation status, while temperature switches respond to temperature changes rather than airflow. Therefore, the flow switch is explicitly designed for the detection of airflow, making it the appropriate choice in this context.