Rheem W2W Series Owner's Manual And Installation Instructions page 60

10. Set time/tariff control on Master heat pump if required. Refer to page 50 to
see the chart for navigating the control panel display.
If the water heater is full of cold water, heating will commence unless the flow
rate of the cold side or the temperature of the cold side and hot side is below
the set point, in which case the auxiliary boost will operate, if installed.
It is important to wait for five minutes after the heat pump has activated to
ensure it continues to operate and is functioning correctly.
Note: The water heater may not turn on immediately when it is first switched
on, if it is switched on within 20 minutes to 2 hours of it having been switched
off at the isolating switch, or the heat pump has just completed a heating cycle.
The water heater will wait until the conditions for start-up are favourable in
order to protect the compressor from damage. This may take up to 20 minutes
to 2 hours. The auxiliary booster (if installed) will operate instead of the heat
pump if the temperature or the flow rate of the cold side is below the set point.
Explain to a responsible officer the functions and operation of the heat pump
water heater. Upon completion of the installation and commissioning of the
water heating system, leave this guide with the responsible officer.
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