What is the function of a relay in an HVAC system?

The function of a relay in an HVAC system is to control a larger load or circuit using a smaller control signal. Relays are electromechanical devices that act like switches, allowing the system to manage heavy electrical loads—such as those for compressors, fans, or heaters—without requiring the control circuit to carry that same load. This capability allows for the safe operation of high-power components using lower voltage control circuits, which can also enhance the reliability and lifespan of the control devices involved.

In HVAC systems, relays enable automation and remote control features, as they can turn large motors or equipment on and off in response to smaller signals from thermostats or control boards. This function is crucial for ensuring that the system operates efficiently while maintaining safety and reducing wear on components.