PURPOSE: To prevent the upper part of a heat collecting pipe from being dried up, and to decrease the necessary quantity of operating liquid in a solar heat water heater, by connecting a plurality of radiating pipes, constituting a condenser part which is housed in a heat exchanger tank, in parallel with one another, and by arranging part of the pipes upwards and the remainder downwards.

CONSTITUTION: A heat exchanger tank 7, housing a condenser part 9 consisting of a plurality of radiating pipes 8, is disposed on the top of a collector 6, as well as to house an evaporator 3, constituted by arranging heat collecting pipes 2 on a heat collecting board, inside the collector 6. The outlet ends of radiating pipes 8 and the inlet part 4 of an evaporator part 3 are connected by a return pipe 13, as well as to connect the inlet part of radiating pipes 8 with the outlet part 5 of an evaporator part 3 by a forward pipe 11. A plurality of radiating pipes 8 are connected in parallel with one another, and part of the pipes are arranged upwards, while the remainder downwards. With such an arrangement, the upper parts of heat collecting pipes 2 are prevented from being dried up, the heat capacity is decreased by decreasing the quantity of an operating liquid. As a result, the performance to collect heat can be heightened in a solar heat water heater.