What is the primary function of a sail switch in HVAC applications?

The primary function of a sail switch in HVAC applications is to detect airflow. It is designed to ensure that there is adequate air movement within the system, typically located in the ductwork or near the blower assembly. When the air flows past the sail switch, the airflow causes the sail or flap to move, indicating that the system is operating correctly. If the airflow is insufficient or fails altogether, the sail switch will not actuate, which can prevent the system from operating, thus protecting the equipment from potential damage due to lack of airflow, such as overheating.

This air detection capability is crucial for maintaining system efficiency and safety, as well as ensuring that heating or cooling processes occur effectively. When the sail switch functions correctly, it helps in optimizing the performance of the HVAC system, making it vital for overall system operations.