PURPOSE: To permit to collect heat independently from the height of the level by a method wherein a hot-water introducing pipe, introduced from a heat collector into a heat accumulating tank upwardly, is constituted of a float pipe, whose hot-water supplying port is ascended or descended by the level of water in the heat accumulating tank.

CONSTITUTION: The hot-water introducing pipe 12, introduced from the solar heat collector 1 into the heat accumulating tank 2 upwardly, is constituted of the float pipe 13 and accordingly the hot-water supplying port 14 of the float pipe 13 is located at the surface of water at all times and fluctuates in accordance with the ascending and descending of the level of water. The float pipe 13 may be constituted of a float 15, for example, and the hot-water supplying port 14 connected to the float 15 through a flexible tube 16. Thus, the hot-water introducing pipe 12 is constituted of the float pipe 13, whose hot-water supplying port 14 is ascended or descended by the water level in the heat accumulating tank 2, therefore, circulation between the heat collector 1 and the heat accumulating tank 2 can be maintained through the float pipe 13 and, accordingly, the heat collecting device 1 is capable of developing the heat collecting function for solar heat independently from the height of the level of water in the heat accumulating tank 2.