The performance of cascade cycle air-source heat pump has been investigated experimentally. The cascade heat pump cycle consists of high temperature of R134a and low temperature of R410a. We have complementary primary air source heat pump. As a result, we produce the products with the best performance. The rated capacity of heat pump is 25kW and the cold capacity of heat pump is 25kW. The KSCOP_C of colder condition is 2.61 and KSCOP_A of average condition is 2.74 and KSCOP_W of warmer is 2.74.

Electric night storage heater was introduced and disseminated for power grid balancing and efficient management of power generation facility. But fuel cost for heating has been increased rapidly while the cost of electricity increased slightly. This abnormal rate system caused peak load in winter at last. To solve this problem, application of an air source heat pump was suggested. In the study, the effect of replacing night heater by heat pump and the economics were analysed. In addition the expectation of prospect of heat pump penetration was simulated based on surveyed and investigated data. As a result, fund supporting as well as institutional backing was needed for effective propagation and return of investment.

The night time electric cost is cheaper due to electric supply and demand policy in Korea from 1985. Currently about 900,000 customers are using night time electric heating boilers and this causes shift of peak demand time to night in winter and increase of deficit spending. To solve this problem, replacing night time electric heating boiler by air-source heat pump using night time electricity has been proposed. An air-source heat pump can provide efficient heating equipment especially in a warm climate. For estimating the night time electric heat pump COP(Coefficient of Performance), Korean Standard KS C 9306:2010 and European Standard EN-14511:2004 is available. SCOP(Seasonal COP) using European weather bin data is also calculated. SCOP is not available yet but European Committee for Standardization will establish a standard in the near future. The evaluation result show that the replacing night time electric heating boiler by heat pump can be possible.