Rheem Stellar 50L Owner's Manual And Installation Instructions page 34

CONNECTIONS – ELECTRICAL
For reasons of safety and economy, we advise the thermostat be set at the
lowest temperature that will provide sufficient hot water. Dishwasher running
costs can be adversely affected if the thermostat is set below 65°C. Discuss the
thermostat setting requirements with the householder.
If this water heater is installed as part of a solar water heating system:

the solar control system must be of a design to limit solar contribution so the
water temperature in the tank does not exceed 80°C. This is necessary to
ensure the solar input does not cause the thermostat's over-temperature cut-
out to operate.

we recommend the water heater thermostat is set at 60°C to maximise solar
contribution.
WIRING DIAGRAM TWIN ELEMENT ELECTRIC WATER HEATERS
NON-SIMULTANEOUS OPERATION OFF-PEAK CONNECTION
Top thermostat – fixed setting
Bottom thermostat – tradesperson adjustable
Electrical Circuit for Twin Element Models – Robertshaw "ST" Thermostats
The active from the continuous supply must be connected to the top heating unit
circuit and the active from the Off-Peak or time controlled supply must be
connected to the bottom heating unit circuit.
60°C.
min 60°C, max 75°C.
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