An indirect circulation system is a solar water heating setup that uses a closed loop of heat-transfer fluid (often antifreeze) to collect solar energy. The fluid passes through a heat exchanger to warm domestic water in a storage tank without mixing. This design prevents freezing and contamination, making it ideal for cold climates.
/ɪnˈdaɪrɛkt ˌsɜrkyəˈleɪʃən ˈsɪstəm/
An indirect circulation system is a solar water heating setup that uses a closed loop of heat-transfer fluid (often antifreeze) to collect solar energy. The fluid passes through a heat exchanger to warm domestic water in a storage tank without mixing. This design prevents freezing and contamination, making it ideal for cold climates.
Why use an indirect circulation system?
It prevents freezing by isolating the solar loop fluid from domestic water.
Source: The Cooling Company
Heat-transfer fluid warms domestic water through a heat exchanger.
A home in a cold climate uses an indirect solar water heater with antifreeze fluid to prevent collector freeze damage in winter.
Check heat-transfer fluid levels and condition on schedule to keep efficiency high.
“Check heat-transfer fluid levels and condition on schedule to keep efficiency high.”
Indirect systems are common in regions where winter temperatures drop below freezing.
Is an indirect system more efficient than direct?
It’s often more reliable in cold climates, though it adds heat exchanger losses.
Does the antifreeze mix ever contact drinking water?
No. The heat exchanger keeps the fluids separate.
Do indirect systems need more maintenance?
They require periodic checks of the heat-transfer fluid and system components.
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