Rheem Optima Owner's Manual And Installation Instructions page 7

SINGLE ELEMENT MODEL
This type of water heater has one heating
unit with its own thermostat. The heating
unit is at the base of the water heater.
Continuous electricity supply
This type of connection is suited to
where the storage capacity is less than
the normal daily usage.
Off-Peak electricity supply
This type of connection will only allow
heating to occur during set hours. A
volume of water sufficient for the day‟s
total use is heated and stored. This type
of heating will be more economical due
to reduced tariffs by the electricity
authority.
TWIN ELEMENT MODEL
This type of water heater has two heating units, each with its own thermostat.
One heating unit is at the base of the water heater and the other near the top.
Bottom heating unit
During normal operation this heating
unit supplies all the hot water.
Top heating unit (Booster)
This heating unit only operates during
periods of high demand to provide an
additional supply of heated water.
Electrical connection
The two heating units are wired for non-
simultaneous operation, so that only
one heating unit can operate at a time.
The bottom heating unit is usually
connected to an Off-Peak (overnight) or
time controlled electricity supply and the
top heating unit to a continuous supply.
Some electricity suppliers allow both
heating units to be metered at the Off-
Peak or controlled tariff.
NOTE: Power must be available to the top heating unit circuit at all times
for this water heater to operate as designed.
ABOUT YOUR WATER HEATER
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