WATER SUPPLIES
16
SATURATION INDEX
The saturation index (SI)
is used as a measure of the water‟s corrosive or
scaling properties.
In a corrosive water supply, the water can attack copper parts and cause them
to fail.
In a scaling water supply calcium carbonate is deposited out of the water onto
any hot metallic surface.
Where the saturation index exceeds +0.40, the water is very scaling. An
expansion control valve must be fitted on the cold water line after the non-
return valve to protect and for the Everhot warranty to apply to the temperature
pressure relief valve and water heater cylinder.
Water which is scaling may be treated with a water softening device to reduce
the saturation index of the water.
Refer to the
on page 16.
Refer to the
on page 32 for the position of the
expansion control valve.
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SATURATION INDEX (SI)
GAS STORAGE WATER HEATERS
WITHIN WARRANTY
SPECIFICATION
SATURATION INDEX
(calculated @ 80°C water temperature)
+0.4
+0.8
0
very corrosive
very scaling
scaling
corrosive
