For split systems equipped with capillary metering devices, which method is used for charging?

The superheat method is the correct charging method for split systems equipped with capillary metering devices due to the nature of how these systems operate. Capillary tubes are fixed metering devices that allow refrigerant to pass through based on varying pressure and temperature conditions. They do not actively regulate refrigerant flow after the system is charged.

When using the superheat method, the technician monitors the enthalpy change of the refrigerant as it passes through the evaporator. By measuring the temperature of the refrigerant gas at the compressor's inlet and the saturation temperature corresponding to the low-side pressure, a technician can calculate the superheat. This allows for an accurate determination of the refrigerant charge by ensuring that enough refrigerant is in the system to allow for complete vaporization in the evaporator while avoiding liquid refrigerant returning to the compressor, which could cause damage.

In summary, the superheat method is particularly effective and necessary with a capillary tube system because it allows for proper management of refrigerant charge, ensuring effective system operation and preventing issues that could arise from incorrect amounts of refrigerant circulating in the system.