Technical data

INSTALLATION – SOLAR STORAGE TANK
24
CIRCULATED HOT WATER FLOW AND RETURN SYSTEM
The solar storage tank of 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.
A Rheem 874 627 series continuous flow water heater can be installed as part of a circulated hot water flow
and return system in a building. If a circulated flow and return system is required, it is necessary to connect
the return line after the solar storage tank and prior to the in-series gas booster. The connecting pipe work
supplied with the water heater may need to be modified in order to install a Tee prior to the water inlet of the
in-series gas booster. Refer to the diagram on page 24.
Notes:
 AS 3498 requires that a water heater provides the means to inhibit the growth of Legionella bacteria in
potable water. The in-series gas booster can satisfy this AS 3498 requirement provided it is energised,
the booster preset outlet temperature setting is 70°C or higher and a remote temperature controller is not
used. The factory preset outlet booster temperature setting is 60°C.
 The circulator must be:
 sized and set to provide a minimum flow rate of 3.0 L/min through the circulated hot water flow and
return system, and
 either thermostatically and / or timer controlled.
The circulator must not be set to operate continuously, i.e. 24 hours per day.
Temperature Limiting Device
A temperature limiting device cannot be installed in circulated hot water flow and return pipe work. The
tempered water supplied from the tempered hot water outlet on this water heater or from another 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 or a dead leg
installed from the tempered water outlet of this water heater.
If circulated tempered water were to be returned back to the gas booster water heater, then 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.
This condition 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 this condition, the operation and performance of the device cannot be
guaranteed.
Circulated Hot Water Flow and Return System – Solar Water Heater
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