INSTALLATION – SOLAR STORAGE TANK
RAINWATER COLLECTION SYSTEM
Before installing a closed circuit system, the installer should determine whether rainwater run-off from the roof
on which the solar collectors will be mounted, is collected in a rainwater tank. If the solar collectors are to be
installed on a section of roof which is part of a rainwater runoff collection system, then it is recommended this
section of roof and its gutter be isolated from the rainwater collection system. The gutter should be isolated to
a width greater than the solar collectors and pipe work and must have suitable drainage. The installer should
ensure in the event of a leak from the closed circuit, a rainwater tank cannot be contaminated with closed
The closed circuit fluid acts as an anti-freeze agent and rust inhibitor, is non-toxic to humans and is harmless
to the environment. However it does have an adverse effect on water stored in rainwater tanks. It will kill
microscopic algae typically present in rainwater tanks and cause an unpleasant odour to develop. This will
result in the rainwater tank having to be drained and cleaned.
The section of roof and gutter should be isolated from the rainwater collection system before the commissioning
of the solar water heater, so that any leak or spillage during commissioning does not make its way into the
The installer should discuss alternative options to suit the installation with the householder. Any alterations to
the roof drainage system must comply with the relevant building regulations, codes and Standards.
Refer to “Rainwater Collection System” on page 7 for additional information on what to do if a rainwater tank
does become contaminated with closed circuit fluid.
The water heater has a freeze protection system. The water heater is not suitable for installation in areas
where the ambient temperature falls below -20°C. The closed circuit fluid is an anti-freeze agent which, when
mixed to the correct specification, can withstand temperatures of -20°C before it may freeze.
To offer protection against freeze damage, the solar circuit must be installed with a continuous fall of a
minimum 5° (1 in 10 grade) in the pipe work from the solar collectors to the solar storage tank, with the full
length of the solar hot and solar cold pipes insulated and the system charged with correctly mixed closed circuit
fluid. The system has NO WARRANTY for freeze damage if there is not a continuous fall in the solar hot and
solar cold pipes or they are not insulated in accordance with the installation instructions or the closed circuit
fluid has been incorrectly mixed (refer to “Terms of the Rheem Warranty” on page 55 and to “Warning: Plumber
Be Aware” on page 29).
The anti-freeze control of the solar circuit is designed so there is no closed circuit fluid in the solar collectors
or solar hot and solar cold pipes when the pump is off. The solar circuit only contains closed circuit fluid when
the pump is operating during periods of solar gain when heating is required. When the solar pump stops
operating, the closed circuit fluid drains back into the storage tank heat exchanger.
Damage to the water heater caused by freezing of the pipe work to or from the water heater is not covered
under the Rheem warranty. Refer to AS/NZS 3500.4 for precautions to be taken for installations in frost prone