A pressure differential switch is used to prove flow in a ______________ system.

A pressure differential switch is commonly used in hydronic systems to ensure that water is flowing correctly through the pipes. These switches monitor the pressure drop across specific components of the system, such as pumps or heat exchangers. If the flow of water is impeded or stopped, the pressure differential will not meet the switch's set parameters, causing it to trigger an alarm or shut down equipment to prevent damage.

In hydronic systems, maintaining proper flow is crucial for efficient operation and to avoid issues like overheating or water hammer. The switch serves as a safety device to prove that the necessary flow exists before allowing the system to operate fully. While pressure differential switches can be found in other types of systems, their primary and most critical role is in hydronic applications where liquid flow needs to be constantly monitored.