To analyze and verify the effect of replacing thermal storage heater by a cascade cycle heat pump using midnight electricity was installed and tested at a customer's house in Wonju, Korea. The electric night storage heater is consist of 30kW electric heater and 2,700 liters of thermal storage water tank to supply hot water for warming house floor. The power for electric heater was cut off and hot water was only generated by cascade cycle heat pump. Current thermal storage water tank was not eliminated and electric heater wiring was modified. Some operation logic of the heat pump was also modified for proper operation. The required capacity of the heat pump and hot water temperature for given warming condition were estimated. The estimated capacity of heat pump was about 19kW and estimated hot water temperature for proper heating was at least 75℃.

Abstract
 1. 서론
 2. 심야 히트펌프 설치
  2.1 설치 지역 및 특징
  2.2 히트펌프 설치 방법
 3. 난방부하 계산
  3.1 전제 조건
  3.2 심야전력 요금에 기반한 난방부하 계산
 4. 결과 및 고찰
 5. 결론
 참고문헌

• 정훈(한전 전력연구원 녹색성장연구소) | H. JUNG
• 황성욱(한전 전력연구원 녹색성장연구소) | S. W. HWANG
• 이철희(한전 전력연구원 녹색성장연구소) | C. H. Lee