Rheem 311 Series Owner's Manual And Installation Instructions page 60

WATER SUPPLIES
CHANGE OF WATER SUPPLY
The changing or alternating from one water supply to another can have a
detrimental effect on the operation and / or life expectation of a water heater
cylinder and a temperature pressure relief valve.
Where there is a changeover from one water supply to another, e.g. a rainwater
tank supply, bore water supply, desalinated water supply, public reticulated
water supply or water brought in from another supply, then water chemistry
information should be sought from the supplier or it should be tested to ensure
the water supply meets the requirements given in these guidelines for the
Rheem warranty to apply.
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
Total Dissolved Solids (TDS) > 2500 mg/L
Total Dissolved Solids (TDS)
not suitable for anode type
Saturation Index (SI) > +0.4
(if expansion control valve is not fitted)
Component
water heater cylinder
water heater cylinder
water heater cylinder
temperature pressure relief valve
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