The thermostatic expansion valve (TXV) is a metering device designed to regulate the flow of liquid refrigerant into the evaporator at a rate equal to the evaporation of the liquid in the evaporator. The TXV responds to both the temperature and the pressure of the refrigerant exiting the evaporator to maintain a constant superheat at the evaporator outlet. Positive superheat at the evaporator outlet in the suction line will help ensure that only refrigerant vapor returns to the compressor.
Here are some tips to ensure maximum TXV performance.