Rheem Optima Owner's Manual And Installation Instructions page 10

REGULAR CARE
TEMPERATURE LIMITING VALVE
The valve should be checked for performance every twelve months. This can
be performed by measuring the water temperature from a hot tap with a
thermometer. If the water is being delivered at a temperature exceeding 55°C,
phone a Rheem Service Centre.
The valve should be replaced at intervals not exceeding 5 years, or more
frequently in areas where there is a high incidence of water deposits (refer to
"Water Supplies" on page 11). Failure to do this may result in water at a
temperature up to 70°C being delivered at the hot tap, increasing the risk of
scald injury.
EXPANSION CONTROL VALVE
An expansion control valve must be fitted to the cold water line to the water
heater. The expansion control valve may discharge a small quantity of water
from its drain line during the heating period instead of the temperature pressure
relief valve on the water heater.
Operate the easing lever on the expansion control valve once every six
months. It is very important you raise and lower the lever gently. The
expansion control valve should be checked for performance or replaced at
intervals not exceeding 5 years, or more frequently in areas where there is a
high incidence of water deposits.
GENERAL MAINTENANCE
The jacket of the water heater can be cleaned with a soft cloth and warm mild
soapy water on a 3 monthly interval in coastal areas. Under no circumstances
should abrasive materials or powders be used.
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