What is the purpose of a differential pressure switch in an HVAC system?

The purpose of a differential pressure switch in an HVAC system is to detect airflow obstructions. This switch monitors the pressure difference between two points, typically across a filter or duct. When airflow is restricted due to dirt buildup in the filter or any other blockage, the pressure difference changes, which triggers the switch. This allows the system to alert users or automatically shut down to prevent damage to the equipment or to ensure efficient operation. By providing this protective function, the differential pressure switch plays a crucial role in maintaining the overall efficiency and safety of the HVAC system.