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Freeze-protection loop for direct solar-water-heating systems. Final report

Technical Report ·
DOI:https://doi.org/10.2172/5753186· OSTI ID:5753186
Even a one-time freeze condition can do destructive damage to a direct solar water heating system. The project funded under grant DE-FG4480R4, 1-1-80 to 8-1-81, proposed to demonstrate a simple installation procedure whereby thermosiphoning warm water from storage would prevent solar collectors from freezing. Installing the freeze protection loop in owner maintained solar systems was inconclusive. Owners were not attentive to freeze warnings or did not understand the simple instructions. A controlled situation was established using a refrigerator to produce below freezing temperatures. Experiments conducted with this equipment showed that the thermosiphoning principle could not be relied on to prevent freezing. Thermosiphoning cannot be relied on to prevent freezing in a direct solar water heating system. The direct system is an effective means of heating water in north Florida, but the system must be drained, either manually or automatically, to provide reliable system protection.
Research Organization:
SOLARFIN, St. Augustine, FL (USA)
DOE Contract Number:
FG44-80R410104
OSTI ID:
5753186
Report Number(s):
DOE/R4/10104-T1; ON: DE84000754
Country of Publication:
United States
Language:
English

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