| CPC F25B 7/00 (2013.01) [F24F 1/14 (2013.01); F25B 30/02 (2013.01)] | 16 Claims |

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1. A heat pump system comprising:
a plurality of compressors including a first compressor and a second compressor, each compressor having a first port and a second port;
a plurality of heat exchangers including a first heat exchanger in communication with the first port of the first compressor, a second heat exchanger, and a third heat exchanger,
wherein the third heat exchanger comprises an input port and a plurality of output ports, such that:
the first port of the second compressor is in fluid communication with the input port of the third heat exchanger,
the second port of the first compressor is in fluid communication with a first of the plurality of output ports of the third heat exchanger;
a plurality of expansion devices including a first expansion device in communication with the first heat exchanger, a second expansion device in communication with the second heat exchanger and with a second of the plurality of output ports of the third heat exchanger, and a third expansion device in communication with the input port of the third heat exchanger,
wherein, when the system operates in a cascade heating mode, the third heat exchanger is configured to:
receive a first portion of refrigerant from the first compressor and a second portion of refrigerant from the second compressor via the input port of the third heat exchanger,
provide a first consistent flow of refrigerant from the second of the plurality of output ports to the first compressor, and
provide a second consistent flow of refrigerant from the first of the plurality of output ports to the second compressor.
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