To determine the subcooling temperature of an operating system, where should you measure?

To determine the subcooling temperature of an operating system accurately, it is essential to measure at the service valve. The service valve is located on the liquid line, which is critical for subcooling calculations. Subcooling is defined as the difference between the saturation temperature of the refrigerant at a given pressure (in the liquid line) and the actual temperature of the refrigerant.

Measuring at the service valve allows you to capture the temperature of the refrigerant after it has condensed but before it has entered the expansion device or evaporator. This ensures that you are assessing the temperature of the refrigerant in its subcooled state, which is necessary for an accurate subcooling calculation.

While other locations, such as the evaporator outlet or compressor inlet, might provide useful temperature readings, they do not give the necessary context for determining subcooling effectively. The outdoor unit, which houses the condenser, also does not provide information at the specific point needed for this measurement, as the refrigerant’s state could vary significantly before it reaches the service valve. Therefore, measuring at the service valve is the appropriate and accurate method for determining the subcooling temperature.