Vision Solar Systems - 100 L Gravity Fed Type
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Issue 2.0 Mar 2013
Principal of Operation
Construction
The system comprises an inner storage tank, an outer cladding and an insulation medium
between the two. A cistern tank with a ball or float valve is attached to the main tank and acts as
a control valve to keep the main tank full. The solar collector consists of vacuum tubes that collect
the energy from the sun, and via thermo siphon, will heat the water in the tank. The tank should
be fitted with a vent pipe connected to the side of the tank, and raised to above the level of the
vent on the cistern tank. This will ensure that the tank is not subjected to any pressure.
These solar water heating systems consist of four major parts as shown in the picture and
detailed below:
The Thermal Storage Tank
The thermal storage tank is a stainless steel tank constructed from 304 stainless steel material
and, being a low pressure tank, we can use a technology we term “no-weld”. This involves all
the pipe connections to the tank using a long life silicon grommet type seal and the end caps
using a pressed and rolled seal. This eliminates welding from the tank and increases the
longevity of the tank as any weld points can act as points where corrosion will start. The tank
holds the potable water, is maintained full of water by the cistern tank, and has the collector
tubes connected to it. Water is drawn from the tank by gravity feed. The tank must be located
above the water outlet, and the pressure of the water is determined by the height of the tank
above the water outlet.
