Rheem Solar Hiline 52D180 Owner's Manual And Installation Instructions page 22

INSTALLATION – SOLAR STORAGE TANK
CIRCULATED HOT WATER FLOW AND RETURN SYSTEM
A solar water heater should not be installed as part of a circulated hot water flow and return system in a
building. The benefits of solar gain will be significantly reduced and energy gained from the sun lost through
the pipe work.
If a circulated flow and return system is required, it is necessary to install a secondary water heater supplied
from the solar water heater. The flow and return lines connect to the secondary water heater, not the solar
water heater. The secondary water heater makes up for the pipe heat loss in the flow and return system and
must be able to provide a hot water outlet temperature of at least 60°C.
If the solar water heater has an in-series booster water heater, then the booster water heater can be used as
the secondary water heater so long as it is able to provide a minimum hot water outlet temperature of at least
60°C and it is not connected to an Off-Peak or time controlled electricity supply.
Note: The thermostat or preset outlet temperature of the secondary water heater must always be set to
maintain a temperature of at least 60°C in the hot water flow and return line, including making up pipe heat
losses in the system.
Circulated Hot Water Flow and Return System – Solar Water Heater
Refer to the
Temperature Limiting Device
A temperature limiting device cannot be installed in circulated hot water flow and return pipe work. The
tempered water from a temperature limiting device cannot be circulated. Where a circulated hot water flow and
return system is required in a building, a temperature limiting device can only be installed on a dead leg,
branching off the circulated hot water flow and return pipe.
If circulated tempered water were to be returned back to the water heater, depending on the location of the
return line connection on the water supply line to the water heater, then either:

water will be supplied to the cold water inlet of the temperature limiting device at a temperature exceeding
the maximum recommended water supply temperature, or

when the hot taps are closed no water will be supplied to the cold water inlet of the temperature limiting
device whilst hot water will continue to be supplied to the hot water inlet of the temperature limiting device.
These conditions may result in either water at a temperature exceeding the requirements of AS/NZS 3500.4
being delivered to the hot water outlets in the ablution areas, or the device closing completely and not delivering
water at all, or the device failing. Under either condition, the operation and performance of the device cannot
be guaranteed.
Circulated Hot Water Flow and Return System – Solar Water Heater
LEGEND
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diagram on page 22.