SOLAR HEAT COLLECTING SYSTEM

PURPOSE:To obtain a solar heat collecting system which does not have an internal pressure rise and energy loss of hot water exhaust by respectively providing solenoid valves in parallel with a circulating pump and at the top of a sealed heat medium tank, and opening the valves when the temperature of the medium reaches near the set temperature, thereby preventing the evaporation, consumption and oxidation, deterioration of antifreeze solution. CONSTITUTION:A heat medium tank 52 is sealed, has no evaporation and consumption of antifreeze solution at the normal operation time, and alleviates the oxidation and deterioration of the solution. When the solution in a heat collector 1 rises to abnormal temperature, a boiling preventive sensor 11 detects the temperature to opens an exhaust solenoid valve 15 and a recovery solenoid valve 16 which are normally closed at the normal time by a signal from a boiling preventive controller 10, and simultaneously stops a heat collecting circulation pump 4. At this time the solution in the collector 1 is recovered through the valve 16 to the tank 52. In this case, air in the upper space of the tank 52 is exhausted from the valve 15, the solution is smoothly recovered, and the inner pressure of the heat collecting system which includes the tank 52 is not simultaneously raised.