Refrigerant charging method, heat source unit, and renewed refrigeration cycle apparatus

A refrigerant charging method of charging a refrigerant to a refrigerant circuit in which a refrigeration cycle is to be performed by a circulating refrigerant, the refrigerant circuit being configured by connecting a heat source unit and a utilization unit to each other, the method comprising:

• (a) charging a first refrigerant to the heat source unit before connecting the heat source unit to the utilization unit to configure the refrigerant circuit;
• and
• (b) connecting the heat source unit to the utilization unit and additionally charging a second refrigerant that differs from the first refrigerant to the refrigerant circuit to obtain the circulating refrigerant that includes the second refrigerant and the first refrigerant that is charged in the heat source unit,
• wherein, after (a), the method comprises transporting the heat source unit with the first refrigerant charged therein to a location where the heat source unit is to be connected to configure the refrigerant circuit,
• wherein, before (b) is performed, a connection pipe connected to the utilization unit and/or the heat source unit is connected to another heat source unit other than the heat source unit at the location and configures another refrigerant circuit that differs from the refrigerant circuit, and
• wherein, in (b), a recovered refrigerant recovered from the other refrigerant circuit is charged as the second refrigerant to the refrigerant circuit.