Rheem Electric Domestic Water Heater - Manual (Page 34)

WATER SUPPLIES
34
SATURATION INDEX
The saturation index 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. Where the saturation index is less than –1.0, the water is
corrosive and a corrosion resistant heating unit should be used.
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 scaling and an expansion control valve* must be fitted on the cold water line
after the non-return valve. Where the saturation index exceeds +0.80, a low
watts density heating unit should be used.
Contact your nearest Rheem Service Department or Accredited Service Agent
if a replacement heating unit is required.
* Refer to the
cold water connection detail on page 23.
WATER HEATERS NOT INSTALLED IN ACCORDANCE WITH THE ABOVE
ADVICE WILL NOT BE COVERED BY THE WARRANTY.