Using solar energy for domestic water heating is one of the most
cost-effective ways to reduce your power bill and the carbon footprint
of a household.
Either evacuated tubes or flat plate collectors can be used for diy
solar hot water. A conventional boiler or immersion heater can be used
to produce hot water for those occasions when the sun does not oblige,
which is often necessary for night-heating or in countries where sun
exposure is weak in winter.
The type of system chosen depends firstly on whether freezing is
likely to occur. In climates where freezing is not a problem, there are
three main options:
- A batch heater
- A direct pump system
- Or a thermosiphon system
A batch heater employs a storage tank for collection; a direct pump
system moves water from a collector to a storage tank; and a
thermosiphon system uses gravity, and no pump.
If temperatures are low enough to cause freezing, then drainback or
closed loop systems with heat exchangers and antifreeze will be
required.
Drainback systems use distilled water to transfer heat, while closed
loop systems circulate antifreeze and use a heat exchanger to transmit
the heat to prevent freezing.
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