EcoSolar Energy Conscious Design Limited
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Figure 4 “One Shot” Backup heating controller, allows manual control of the backup heating. The
heating is manually turned on and will be automatically turned off, maximising the savings from the
solar system
Timeclock
– the electric elements or boiler are switched on at a predetermined time towards the
end of the day, once the cylinder has been heated by the sun, and only in the event that the water is
not up to the desired temperature. The modern solar controller as shown in Figure 3 above, is able to
determine cylinder temperatures and turn the electric elements or boiler on if required.
Wetback
Combined solar and wetback heated installations are becoming increasingly common. The solar
system heats the cylinder in the normal way either as a direct or indirect circuit and the wetback
heating is provided directly in an open vented cylinder, or via a heat exchanger in a valve vented
cylinder.
If the wetback is some distance from the cylinder and unable to operate as a thermosyphon system,
the water is able to be pumped between the wetback and cylinder. Some solar controllers, such as the
one shown in Figure 3 above, are able to not only control the solar system, but are also able to
control the wetback circulating pump. The solar controller monitors the temperatures in the wetback