The present invention is to provide a heat recovery storage device, which includes a major container, a heat transfer machine mounted in the major container, and a thermostatic valve mounted on the heat transfer machine. And the heat transfer machine is used for conducting heat transfer directly to the water in the major container, thus the efficiency of recovery increases, and loss of heat decreases. Also, the water is not easily boiled during the heat recovery, and the maximum of water temperature can increases. In extended use of more than one device of the present invention, each of the major containers can be installed with or without a heat transfer machine as required. The bypass outgassing control is not needed during the heat recovery, and is performed when the water temperature in the containers reaches to the highest.