HEAT ACCUMULATION DEVICE

PURPOSE: To reliably prevent mixture of a heating medium to a water circulation system and meanwhile mixture of water to a heating medium circulation system when water and the heating medium are exchanged with each other. CONSTITUTION: A heat accumulation device comprises a heat accumulation feed system 9 having a heat accumulation tank 2, a heat load 5, and a heat accumulation pump 10, a heating medium 2, and a heating medium circulation pump 4a, and a water circulation system 3b having the heat pump 1, a heat load 5, and a water circulation pump 4b. The water circulation system 3b and the heating medium circulation system 3a are connected together through a three-way valve 12b on the heat pump side and a heating medium circulation system 3a and the water circulation system 3b are connected together through a three-way valve 12a on the pump inlet side. A heat accumulating device comprises a bypass system 7b connected to a water circulation system 3b from the water circulation system 3b through a bypass three-way valve 12c, a separator 6, and a water auxiliary pump 8a, and a bypass system 7c connected to the heating medium circulation system 3a through a separator 6 and a medium auxiliary pump 8b.