How long should a system run before measuring superheat?

The correct approach to measuring superheat in a refrigeration or air conditioning system is to allow it to run long enough for temperature and pressure to stabilize. Superheat is the temperature of a refrigerant vapor above its saturation temperature at a given pressure. Accurate measurements depend on the system operating under stable conditions, as fluctuations can lead to erroneous readings.

When the system is allowed to stabilize, all components, including the evaporator and compressor, reach their normal operating conditions. This ensures that the superheat measurement reflects the actual performance of the system rather than transient conditions that may not represent standard operation.

While running the system for at least 10 minutes might seem reasonable, it's not a strict requirement; the key factor is stabilization, which can vary depending on the specifics of the system and the environment. Reaching full operational capacity is also not a definitive answer since it doesn’t consider the necessary stabilization period for accurate pressure and temperature readings. Measuring superheat as soon as the compressor starts does not provide enough time for these conditions to stabilize, likely leading to misleading results.