PURPOSE: To reduce the heat emission of a pipeline without spoiling convenient property that hot-water is discharged immediately after opening a hot-water supplying cock by a method wherein a hot-water supplying pump and the hot-water supplying cock are connected by a double pipe and the inner pipe thereof is provided with a non-return valve at the side of a hot-water reserving tank while a bypass pipe communicating the inner pipe with the hot-water reserving tank is provided in this device.

CONSTITUTION: The inner pipe 11, whose both ends are opened, is provided in the pipeline 9 between the pump 2 and the hot-water supplying cock 3. The non-return valve 13 is attached to the inner pipe 11 at the side of the hot-water reserving tank so that water in the inner pipe 11 is not flowed from the hot-water supplying cock 3 side to the pump toward the hot-water reserving tank 4 side. The bypass pipe line 12, communicating the inner pipe 11 with the hot-water reserving tank 1 is provided between the inner pipe 11 and the tank 1. When the pump is operated in a condition that the cock 3 is closed, the hot-water 4 in the tank 1 moves to the cock 3 through an outer pipe 9. Thereafter, the hot-water returns into the tank 1 again through the inner pipe 11 and the bypass pipe 12. The non-return valve 13 effects when the hot-water passes through the inner pipe 11, therefore, the hot-water 4 will never flow reversely toward the pump 2 and returns into the tank 1 again through the bypass pipe 12.