Heat pump apparatus

A heat pump apparatus comprising:

• a plurality of load devices each being configured to adjust a temperature of a temperature adjusting target in a target space of a plurality of target spaces by using refrigerant;
• a heat source apparatus configured to adjust the temperature of the refrigerant;
• a relay unit connected to the heat source apparatus and the plurality of load devices via refrigerant pipes for circulating the refrigerant, the relay unit being configured to switch a flow passage of the refrigerant based on an operational state of each of the plurality of load devices;
• and
• a controller configured to control the heat source apparatus, the plurality of load devices, and the relay unit,
• wherein
• the relay unit includes a plurality of three-way linear expansion valves, and
• each of the plurality of three-way linear expansion valves is provided at a refrigerant pipe of the refrigerant pipes, connected to corresponding one of the plurality of load devices, configured to switch a flow passage of the refrigerant flowing through the corresponding one of the plurality of load devices, and having an opening degree controlled gradually from a closed state to a fully open state to adjust a flow rate of the refrigerant flowing through each of the plurality of load device.