The static setting of a thermostatic expansion valve is measured in:

The static setting of a thermostatic expansion valve (TXV) is measured in degrees of superheat because the TXV operates based on the superheat of the refrigerant vapor exiting the evaporator. Superheat refers to the temperature of the refrigerant vapor above its saturation temperature at a given pressure.

This measurement is crucial for the proper functioning of the TXV as it helps to ensure that the refrigerant is in a vapor state before it enters the compressor, preventing compressor damage due to liquid refrigerant. The valve adjusts its opening based on the superheat level, allowing more or less refrigerant to flow into the evaporator depending on the cooling load and the temperature of the refrigerant.

Understanding superheat is essential for diagnosing and optimizing HVAC systems, as it directly affects the efficiency and performance of the refrigeration cycle. The correct adjustment of the TXV in relation to superheat allows for effective temperature control and system reliability.