Indoor unit for heat pump use apparatus and heat pump use apparatus including the same

An indoor unit for a heat pump use apparatus, the indoor unit being a part of the heat pump use apparatus comprising a refrigerant circuit configured to circulate refrigerant, a heat medium circuit configured to allow a heat medium to flow through the heat medium circuit, and a heat exchanger configured to exchange heat between the refrigerant and the heat medium, the indoor unit being connectable to an outdoor unit accommodating the refrigerant circuit and the heat exchanger, the indoor unit accommodating a part of the heat medium circuit,

• the indoor unit comprising:
• a pressure protection device connected to the heat medium circuit;
• an on-off device provided to be interposed between the heat medium circuit and the pressure protection device;
• and
• a controller configured to control the on-off device,
• the controller being configured to open and close the on-off device on a basis of information acquired from the outdoor unit.