INSTALLATION – WATER HEATER
17
HOT WATER DELIVERY
This 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 water heater and
the hot water outlets in any ablution and public areas such as a bathroom, ensuite or public amenities, to
reduce the risk of scalding. The installing plumber may have a legal obligation to ensure the installation of
this 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 or public area.
The temperature limiting device used with a continuous flow gas water heater should have:
a specified
„minimum temperature differential‟ between the hot water inlet and the tempered water outlet
of no greater than 10°C, and
a specified
„maximum permitted pressure variation‟ in the supply between the hot water inlet and the
cold water inlet of no less than 15%.
Refer to the specifications of the temperature limiting device.
The temperature limiting device used with an in-series gas booster as part of a solar water heater
installation must have the additional capability of receiving a hot water supply temperature of up to 99°C if
the solar water heater does not have an over temperature protection system to limit the water to no greater
than 90°C.
Warning:
Temperature controllers
must not
be fitted to this water heater as part of a solar water heater
system because water at a temperature much higher than the controller setting can be delivered.
Where a temperature limiting device is installed adjacent to the in-series gas booster, 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 tank, but it
MUST BE
before the non return valve prior
to an open circuit direct system. The cold water line to the temperature limiting device can be branched off
the cold water line either before or after the non return valve prior to a closed circuit indirect system. 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 tank.
Warning:
A non return valve
MUST BE
installed on the cold water line to the solar storage tank
AFTER
the cold water branch to a temperature limiting device prior to an open circuit direct system. Due to the
higher water temperatures generated under certain conditions in the solar collectors of an open circuit direct
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 combination isolation valve and non return valve (duo or trio valve) is installed on the cold water line to
an open circuit direct 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. Due to the higher water temperatures generated under certain conditions in the solar
collectors of an open circuit direct pumped 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.
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.
