A company operates a large ammonia refrigeration plant for production. In operating the refrigeration system, heat is generated which is unutilized as the temperature level is too low (35°C). As a solution an additionalcompression stage with a separate piston compressor shall be integrated directly into the refrigeration circuit to raise the waste heat to a higher and thus usable temperature level. The temperature can then be connected directly to the existing heating system. In doing so total efficiency gains can be achieved.