Which adjustment is critical to prevent starving the evaporator?

Superheat is critical to prevent starving the evaporator because it ensures that only vapor enters the evaporator coil, thus maintaining efficient operation and preventing liquid refrigerant from returning to the compressor. In an HVAC system, superheat is the temperature difference between the vapor refrigerant leaving the evaporator and its saturation temperature at the corresponding pressure.

If superheat is too low, it indicates that liquid refrigerant may still be present in the suction line, which could lead to the compressor being exposed to liquid, potentially causing damage. Conversely, if superheat is set correctly, it guarantees that the evaporator is fully utilizing the refrigerant, allowing for optimal heat absorption and preventing the risk of liquid slugging in the compressor.

The other options, while important in HVAC operations, do not specifically address the prevention of evaporator starvation in the same manner. Sub-cooling pertains to conditions on the condensing side and focuses more on ensuring that refrigerant is completely liquid before it enters the expansion device. Pressure relates to system operation but does not directly dictate the flow and state of refrigerant in the evaporator like superheat does. Temperature is a broader term that can apply to various systems but doesn’t specifically capture the nuances of evaporator performance and the risks of starving