Abstract: Disclosed is a heat accumulation tank system intended for use as a heat source of, for example, an air conditioner and which is installed, for example, in a building or under a green zone, a stadium or a parking area. The heat accumulation tank system is composed of a plurarity of water tanks which are connected through a communication passage such as a communication pipe. The pressure in the communication passage is controlled by means of a pressurizing device or a vacuum device, so that the state of communication is controlled such as to establish or interrupt the communication between the water tanks or to control the rate of flow of water between these water tanks.

Abstract: Disclosed is a heat accumulation tank system intended for use as a heat source of, for example, an air conditioner and which is installed, for example, in a building or under a green zone, a stadium or a parking area. The heat accumulation tank system is composed of a pularity of water tanks which are connected through a communication passage such as a communication pipe. The pressure in the communication passage is controlled by means of a pressurizing device or a vacuum device, so that the state of communication is controlled such as to establish or interrupt the communication between the water tanks or to control the rate of flow of water between these water tanks.