Describes the characteristics of a high-performance heat pump cycle for hot water supply - the two-stage compression and cascade heat pump cycle (TCCH cycle). Also presents the characteristics of the intermediate heat exchanger, which is s key component of the high performance capabilities characteristic of the TCCH cycle. Supplies the results of performance verification for the trial manufactured system and the improved system, which are for commercial use. The difference between these systems is the heat exchanger design.

KEYWORDS: year 1996, Heat pumps, domestic, hot water supply, compression heat pumps, Japan, commercial, coefficient of performance