ABOUT YOUR WATER HEATER
14
BOOSTER CONTROL
An isolating switch is installed in the electrical meter box for the solar storage tank, and a second isolating
switch may be installed adjacent to the solar storage tank. These should be left switched on to allow the booster
heating unit to operate if required. 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.
Leaving the isolating switch(s) switched on will also provide a sufficient period of time each day for the booster
heating unit to operate, if required, to satisfy the requirements of AS 3498.
The booster heating unit will only activate if heating is required and power is available from the switchboard.
When the water is below the thermostat setting, the booster heating unit will turn on and heat the water. The
booster heating unit will automatically turn off when the temperature of the water reaches the thermostat
setting.
Timer Control Switch
A suitably rated timer control switch can be installed and will help maximise energy savings with an electrically
boosted solar water heater connected to a
continuous, time of use
or extended Off-Peak (overnight and
day)
electricity supply. Further information for a licenced electrical worker on the recommended methods of
wiring the timer are outlined in
on page 51.
Programming the Timer
Power must be available to the timer control switch before the booster heating unit can be activated.
The timer control switch should be programmed:
•
to suit the hot water consumption pattern of the household,
•
with the end of the period to coincide with the commencement of the evening hot water usage,
A second period, such as prior to the morning hot water usage, may be necessary.
•
to enable a boosting period of not less than the recommended continuous length of time for boosting,
•
for a period when power will be available to the timer.
Note:
When daylight saving time applies, you may consider resetting the timer accordingly.
The recommended continuous length of time for boosting is:
Booster heating unit size
Model
Minimum winter
cold water temperature
Temperature
rise
2.4 kW
3.6 kW
4.8 kW
270
Cool / temperate climate
10°C
50°C
3 ½ hours
2 ½ hours
1 ¾ hours
Temperate / sub-tropical climate
15°C
45°C
3 ¼ hours
2 ¼ hours
1 ¾ hours
Tropical climate
20°C
40°C
2 ¾ hours
2 hours
1 ½ hours
320
Cool / temperate climate
10°C
50°C
4 ¼ hours
3 hours
2 ¼ hours
Temperate / sub-tropical climate
15°C
45°C
3 ¾ hours
2 ½ hours
2 hours
Tropical climate
20°C
40°C
3 ½ hours
2 ¼ hours
1 ¾ hours
410
Cool / temperate climate
10°C
50°C
5 ½ hours
3 ¾ hours
2 ¾ hours
Temperate / sub-tropical climate
15°C
45°C
5 hours
3 ¼ hours
2 ½ hours
Tropical climate
20°C
40°C
4 ½ hours
3 hours
2 ¼ hours
Factory fitted booster heating unit size is 3.6 kW
The recommended boosting periods are sufficient to allow the booster heating unit to heat up the boost volume
of the solar storage tank to 60°C where the winter cold water temperatures do not fall below those shown. This
may be necessary during periods of no or very low solar energy gain through the solar collectors, such as
during constant rain or extremely cloudy weather, particularly in winter when the incoming cold water
temperature is lower. The period will also provide a sufficient heat up time for the electric booster to operate,
if required, to satisfy the requirements of AS 3498.
The booster heating unit will only activate if heating is required and power is available from the timer. When
the water is below the thermostat setting, the booster heating unit will turn on and heat the water. The booster
heating unit will automatically turn off either when the temperature of the water reaches the thermostat setting
or at the end of the timer period, whichever comes first.
