Rheem Stellar 8A0 330 Owner's Manual And Installation Instructions page 17

WATER SUPPLIES
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 Rheem warranty to apply to the temperature
pressure relief valve and water heater cylinder.
Where the saturation index exceeds +0.80, the Rheem warranty does not apply
to a stainless steel cylinder.
Water which is scaling may be treated with a water softening device to reduce
the saturation index of the water.
Refer to the Saturation Index chart on page 17.
Refer to the cold water connection diagram on page 32 for the position of the
expansion control valve.
SATURATION INDEX (SI)
GAS STORAGE WATER HEATERS - STAINLESS STEEL
WITHIN WARRANTY
SPECIFICATION
-1.0 0 +0.4 +0.8
SATURATION INDEX
(calculated @ 80°C water temperature)
scaling
very corrosive corrosive very scaling
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