Rheem Optima Owner's Manual And Installation Instructions page 23

INSTALLATION
Off-Peak or Time Controlled Electricity Supply
A single or twin element electric water heater connected to an Off-Peak
electricity supply should not be installed as part of a circulated hot water flow
and return system in a building. The benefits of the Off-Peak electricity supply
will be significantly reduced.
REDUCING HEAT LOSSES
The cold water line to and the hot water line from the water heater must be
insulated in accordance with the requirements of AS/NZS 3500.4. The
insulation must be weatherproof and UV resistant if exposed. When using a hot
water recirculation system, an increase in running costs can be expected due
to the heat loss that occurs through the pipework.
The cold water line to and the hot water line from the water heater must be
insulated in accordance with the requirements of AS/NZS 3500.4. The
insulation must be weatherproof and UV resistant if exposed.
Circulated Hot Water Flow and Return
Continuous Electric Water Heater
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