The safety device that is used to start the compressor when excessively high head pressure develops is called what?

The safety device that is used to start the compressor when excessively high head pressure develops is known as a spring load relief valve. This device plays a critical role in protecting the compressor from damage due to high pressure, which can occur in refrigeration and air conditioning systems.

When head pressure exceeds a predetermined limit, the spring-loaded relief valve opens to allow excess refrigerant to escape the system, thereby lowering the pressure and permitting the compressor to operate safely without risking potential failure or overheating. This ensures the system remains within safe operating conditions, thus prolonging the life of the compressor and enhancing the overall efficiency of the refrigeration or air conditioning system.

In contrast, while pressure switches, thermostatic expansion valves, and overload protectors have their own critical roles in managing and safeguarding HVAC systems, they do not specifically function to manage excessively high head pressure in the same way that a spring load relief valve does. The pressure switch typically serves to turn the system on or off based on specific pressure levels, while the thermostatic expansion valve regulates refrigerant flow and an overload protector prevents motor damage from overheating.