Air-conditioning apparatus

An air-conditioning apparatus comprising:

• a refrigerant cycle circuit in which a compressor, a heat-source-side heat exchanger, an expansion device, and a refrigerant-side flow passage of an inter-heat-medium heat exchanger are connected by refrigerant pipes, and refrigerant is circulated, the inter-heat-medium heat exchanger being configured to cause heat exchange to be performed between the refrigerant and a heat medium;
• and
• a heat-medium cycle circuit in which a pump, a use-side heat exchanger, and a heat-medium-side flow passage of the inter-heat-medium heat exchanger are connected by heat-medium conveying pipes, and the heat medium is circulated,
• wherein an inside diameter D of each of the heat-medium conveying pipes satisfies the following formula (1):
• 3(LQ2)0.2<D<104(Q/L)0.5 (1),
• where
• D is a numerical value of the inside diameter expressed in mm,
• Q is a numerical value of a capacity expressed in kW of the use-side heat exchanger connected to the heat-medium conveying pipes, and
• L is numerical value of a length expressed in m of at least one of the heat-medium conveying pipes included in the heat-medium cycle circuit, wherein
• a plurality of use-side heat exchangers including the use-side heat exchanger are provided,
• the heat-medium conveying pipes include
• a plurality of use-side pipes each connected to an associated one of the plurality of use-side heat exchangers, and
• a heat-source-side pipe connected to the inter-heat-medium heat exchanger, and
• of the inside diameters D of the heat-medium conveying pipes, an inside diameter Da of the heat-source-side pipe satisfies the formula (1), where a total capacity Qa of the plurality of use-side heat exchangers is substituted for the capacity Q and a length La of the heat-source-side pipe is substituted for the length L,
• further comprising:
• a heat source unit including at least the compressor and the heat-source-side heat exchanger;
• and
• a relay unit connected to the heat source unit by a pipe, and including at least the inter-heat-medium heat exchanger,
• wherein the plurality of use-side pipes each connect the relay unit and an associated one of the plurality of use-side heat exchangers;
• and
• an auxiliary relay unit connected between the relay unit and the plurality of use-side heat exchangers,
• wherein the heat-medium conveying pipes further include an intermediate pipe connecting the relay unit and the auxiliary relay unit, and
• an inside diameter Db of the intermediate pipe satisfies the formula (1), where a total capacity Qb of the plurality of use-side heat exchangers connected to the auxiliary relay unit is substituted for the capacity Q and a length Lb of the intermediate pipe is substituted for the length L,
• wherein the inside diameter Db of the intermediate pipe is larger than an inside diameter of each of the plurality of use-side pipes.