HEAT PUMP HEATING APPARATUS

摘要

The purpose of the present invention is to provide a heat pump heating apparatus that is able to continue two-stage operation without having to stop a high-stage compressor when the return temperature of a heat carrier reaches a prescribed high temperature and is hence able to mitigate the feeling of insufficient heating caused by the high-stage side compressor being stopped as well as the feeling of insufficient heating caused by frequent defrosting operations. To achieve this objective, this heating apparatus is provided with: an internal heat exchanger (second internal heat exchanger) in which a low-temperature refrigerant on the low-pressure side of a low-stage side refrigeration circuit and a high-temperature refrigerant on the high-pressure side of a high-stage side refrigeration circuit exchange heat; a bypass pipe for bypassing the internal heat exchanger; and a flow channel-regulating means for regulating the refrigerant circulation in the internal heat exchanger and in the bypass pipe.