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ABOUT YOUR WATER HEATER
ELECTRIC BOOSTING
Water stored in the solar storage tank can be heated by an electric booster heating unit. The booster heating
unit is for heating the water at times of low solar energy gain, such as during very cloudy or rainy weather, or
during the colder months.
The amount of water heated by the raised booster heating unit of the thermosiphon solar storage tank is
90 litres (180 tank) or 150 litres (300 tank).
The thermosiphon solar water heater is most suited for the booster heating unit to be connected to either a
continuous, or a time of use, or an extended Off-Peak (overnight and day) electricity supply. A timer can also
"Booster Control"
be used to control the boosting periods and help maximise solar savings. Refer to
on
page 14.
The booster heating unit may be connected to an Off-Peak (overnight) electricity supply, however this will only
allow the booster to heat the water overnight. If this type of connection is considered, care must be taken to
ensure there is sufficient boost capacity to meet the household's full day and night's hot water supply during
periods of no or low solar gain, particularly in cold weather. There is also an increased risk of temperature run
"Temperature Redistribution"
down occurring, particularly in cooler weather (refer to
on page 23).
The booster heating unit is controlled by an electric thermostat. The thermostat and its over temperature energy
cut out are mounted on the solar storage tank behind the front cover. The water temperature is automatically
controlled to the thermostat setting when the booster heating unit is energised.
HOW HOT SHOULD THE WATER BE?
The temperature the system will operate at under solar radiation will
typical maximum temperature
depend upon the level of solar radiation available, orientation and
from solar gain
inclination of the solar collectors, incoming cold water temperature
maximum booster setting
and volume of hot water used.
Under normal household use and average operating conditions, the
minimum booster setting
system may achieve a water temperature of approximately twice the
maximum daily outside air temperature. In summer solar conditions
this can be up to 60°C to 75°C. This water temperature can be
maximum recommended
exceeded and reach up to 95°C during periods of high solar
supply temperature to
bathrooms and ensuites
radiation conditions and reduced hot usage.
During periods of low solar energy gain, the water temperature can
be boosted by the thermostatically controlled electric booster
"Booster Control"
heating unit. Refer to
on page 14.
Rheem recommends the thermostat is set at 60°C to maximise solar
contribution.
Note: AS 3498 requires that a water heater provides the means to inhibit the growth of Legionella bacteria in
potable water. This water heater can satisfy this AS 3498 requirement provided the electric booster is
energised for a sufficient period each day and the electric booster thermostat setting is 60°C or higher.
If this water heater is installed with an in-series continuous flow gas booster, then this requirement of AS 3498
can be satisfied provided the booster is energised, its preset outlet temperature setting is 70°C or higher and
a remote temperature controller is not used.
If this water heater is installed with an in-series storage booster, then this requirement of AS 3498 can be
satisfied provided the storage booster is energised and its thermostat setting is 60°C or higher.
HOTTER WATER INCREASES THE RISK OF SCALD INJURY
This water heater can deliver hot water at temperatures which on occasion could exceed 75°C, sufficiently hot
to cause severe scalding. Water at this temperature may have been plumbed to fixtures where water hotter
than 50°C is allowed, such as the kitchen and laundry.
Check the water temperature before use, such as when entering a shower or filling a bath or basin, to ensure
it is suitable for the application and will not cause scald injury.
12
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