What is superheat, and what does it tell about a system’s operation? The term superheat generally is used to describe the state of a refrigerant. Refrigerant in its vapor state is said to be superheated because it is at a temperature above its saturation (boiling point) temperature. The degree at which a refrigerant is superheated is the temperature difference between its actual temperature and its saturation temperature. For example, if the saturation temperature of a refrigerant is 20°F and its actual temperature is 30°, then the refrigerant is said to be superheated by 10°. This could be also stated as “the refrigerant has 10° of superheat.”
In a properly operating system, the refrigerant will be in a superheated state from the last section of the evaporator to the first section of the condenser. Technicians can measure the superheat condition anywhere along this path. Two common locations are at the outlet of the evaporator and the inlet of the compressor. When measured at the outlet of the evaporator, it’s typically referred to as “evaporator superheat,” and when measured at the inlet of the compressor, it’s typically referred to as “total system superheat.” Refrigerant superheat is also occasionally measured at the outlet of the compressor, which is referred to as “compressor superheat.”