ABOUT YOUR WATER HEATER
5
Normal operation
As the sun heats the water in the solar collectors, the increase in temperature activates the circulator. The
circulator switches on whenever the water in the solar collectors is hotter than the water in the solar storage
tank. The circulator moves the hotter water from the solar collectors through the solar hot pipe to the solar
storage tank and the cooler water from the solar storage tank is circulated to the solar collectors via the solar
cold pipe
to be heated by the sun‟s energy.
This process continues whilst solar energy is available and the water in the solar storage tank requires
heating. The circulator will deactivate when the water temperature in the solar storage tank is around 70°C to
75°C. The water heater will then enter Over-temperature operation.
During normal operation if the amount of solar energy available reduces, such as when the sky becomes
very cloudy or the sun becomes lower in the sky in the late afternoon, and the water no longer gains useable
heat from the solar collectors, the circulator will deactivate. The water heater will then enter standby mode.
Over-temperature operation
The purpose of the Over-
temperature operation is to reduce the amount of overheating or „stagnation‟ of
water in the solar collectors. When the water in the solar storage tank has reached 70°C to 75°C and the
circulator has deactivated, the solar collectors will continue to gain heat while solar energy is still available.
If the water in the solar collectors stagnates and its temperature becomes very high, the circulator will
activate for a short period to transfer this extra energy to the solar storage tank. The circulator will deactivate
when the water temperature in the solar collectors decreases. This process will either repeat for a maximum
of eight cycles or until the water temperature in the solar storage tank reaches around 75°C to 80°C or the
hot sensor does not sense another increase in water temperature to a stagnation level after a cycle is
completed, i.e. the solar energy available reduces.
Night Time Cooling operation
The purpose of Night Time Cooling operation is to rid the solar storage tank of excess solar energy gained
by Over-temperature operation during that day. The desired water temperature in the solar storage tank is to
be between 60°C to 70°C.
If the solar control unit has entered Over-temperature operation during the day, then after the water
temperature in the solar collectors reduces later in the day or early evening, the circulator will activate. Water
from the solar storage tank will circulate through the solar collectors and excess heat in the water will radiate
from the solar collectors reducing the temperature of the water. The water will circulate for a period of time
and until the water temperature in the solar storage tank is around 60°C to 70°C. The water heater will then
enter standby mode.
Freeze Protection operation
The purpose of Freeze Protection operation is to prevent freezing of water in the solar collectors and solar
pipe work in very cold conditions. The water in the solar collectors will cool during periods of no solar gain. In
very cold conditions, such as overnight and very early in the morning before sunrise, the water temperature
can approach freezing point.
If the hot sensor measures that the water temperature in the solar collectors is approaching freezing, the
circulator will activate. Water from the solar storage tank, containing more energy than the water in the solar
collectors, will circulate through the solar collectors keeping the water temperature above freezing point. The
circulator will remain on for some minutes and until the hot sensor measures a water temperature at a safe
level above freezing. When both of these conditions are met, the circulator will deactivate. The water heater
will then enter standby mode.
This process will repeat whenever the hot sensor measures that the water temperature in the solar collectors
is approaching freezing.
Refer to
on page 10 and
on page 10.
Standby mode
The water heater will be in Standby mode whenever conditions are not favourable for solar heating in Normal
operation, and Over-temperature operation and Night Time Cooling are not required or have been
completed, and conditions are not cold enough for or in-between Freeze Protection operation.
