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INSTALLATION – SOLAR STORAGE TANK
If a pressure limiting valve is installed on the cold water line to the solar water heater and the cold water line
to a temperature limiting device branches off before this valve or from another cold water line in the
premises, then a pressure limiting valve of an equal pressure setting may be required prior to the
temperature limiting device.
If a combination isolation valve and non return valve (duo or trio valve) is installed on the cold water line to
the solar water heater and the cold water line to the temperature limiting device branches off after this valve,
then a second non return valve must be installed between the cold water branch and the 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 bypass the solar water heater and install
a secondary water heater connected to the hot water flow and return line and supplied from the solar water
heater. The secondary water heater must be a storage water heater able to provide a hot water outlet
temperature of at least 60°C. Note: The thermostat must always be set to at least 60°C. Refer to the
diagram on page
22.
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
22
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