Rheem STELLAR 4A Series Owner's Manual And Installation Instructions page 22

WATER SUPPLIES
TOTAL DISSOLVED SOLIDS
The stainless steel cylinder of the water heater is only covered by the Rheem
warranty when the total dissolved solids (TDS) content in the water is less than
600 mg / L.
Note: Some water analysis reports may state the conductivity of the water rather
than the level of total dissolved solids. Conductivity, measured in microsiemens
per centimetre (µS / cm), is directly proportional to the TDS content of the water.
TDS, in mg / L, is approximately 70% of the conductivity in µS / cm.
SUMMARY OF WATER CHEMISTRY ADVICE AFFECTING WARRANTY
The water heater and its components are not suitable for certain water
chemistries. Those chemistries are listed below. If the water heater is connected
at any time to a water supply with the following water chemistry, the Rheem
warranty will not cover any resultant faults on the components listed below:
Water Chemistry
Chloride > 250 mg / L
pH < 6.0 or > 9.5
Total Dissolved Solids (TDS) > 600 mg / L
Saturation Index (SI) < -1.0
Saturation Index (SI) > +0.4
(if expansion control valve is not fitted)
Saturation Index (SI) > +0.8
Component
water heater cylinder
water heater cylinder
water heater cylinder
copper sheathed heating unit
water heater cylinder
temperature pressure relief valve
water heater cylinder
standard watts density heating unit
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