Compact heat pump for cold climate applications

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.