26
General Plumbing Arrangement & Plumbing Diagrams
Two Temperature Zones Using a Temperature Limiting Device
This solar water heater can deliver water at temperatures which can cause scalding.
It is necessary and we recommend that a temperature limiting device be fitted between the solar water
heater and the hot water outlets in any ablution area such as a bathroom or ensuite, to reduce the risk of
scalding.
The installing plumber may have a legal obligation to ensure the installation of this solar water heater meets
the delivery water temperature requirements of AS/NZS 3500.4 so that scalding water temperatures are not
delivered to a bathroom, ensuite or other ablution area.
The temperature limiting device used with a solar water heater should be capable of receiving a hot water
supply temperature of up to 99°C and have a specified
„minimum temperature differential‟ between the hot
water inlet and the tempered water outlet of no greater than 10°C. Refer to the specifications of the
temperature limiting device.
In addition, the temperature limiting device used with a continuous flow gas booster should have a specified
„maximum permitted pressure variation‟ in either supply between the hot water inlet and the cold water inlet
of no less than 15%.
Where a temperature limiting device is installed adjacent to the solar water heater, the cold water line to the
temperature limiting device can be branched off the cold water line either before or after the isolation valve
and pressure limiting valve to the solar storage cylinder, but it
MUST BE
before the non return valve. If an
expansion control valve is required, it must always be installed after the non return valve and be the last
valve prior to the solar storage cylinder.
Warning:
A non return valve
MUST BE
installed on the cold water line to the solar storage cylinder
AFTER
the cold water branch to a temperature limiting device. Due to the high water temperatures
generated under certain conditions in the solar collectors of this solar water heater, an additional effective
back-flow prevention device also should be used as an extra safeguard. Valve manufacturer RMC
recommends Dual Check Valve model N7150, as being suitable for this application.
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 premise,
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 water heater.
Due to the high water temperatures generated under certain conditions in the solar collectors of this solar
water heater, an effective back-flow prevention device should be used as the second non return valve as an
extra safeguard. Valve manufacturer RMC recommends Dual Check Valve model N7150, as being suitable
for this application.
Warning:
Temperature controllers
must not
be fitted to the gas booster because water at a temperature
much higher than the temperature controllers setting can be delivered.
Refer to
“Two Temperature Zone Plumbing Diagrams” on page 27.
