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The Timer/Boost Temp setting sets the required temperature when Apollo GEM is heating the
water in timer or boost modes. Since operation in these modes will usually be using imported
power a lower temperature can be set to minimise the use of imported power.
The Optimiser Temp setting sets the required temperature when Apollo GEM is heating the
water with “free” surplus PV power. The make the most of surplus optimised power a higher
temperature can be set for this mode.
Note that to reduce the risk of scalding hot water temperature should not be set higher than
65
o
C.
If the hot water feed from the tank is fitted with a blending valve, a valve that mixes cold water
with the hot water from the cylinder to limit the hot water output to a preset (safe) temperature,
then higher tank temperatures than 65
o
C could be used. The advantage of a higher tank
temperature is that this will enable more energy to be stored in the tank.
Note: If the Apollo GEM temperature sensor is being used to control the water temperature
the electric hot water element thermostat should be adjusted up to its maximum in order to
prevent the electric hot water thermostat interfering with the Apollo GEM sensor temperature
control.
Some standard electric water thermostats can only be adjusted up to a maximum of 60 or 65
o
C
and therefore a higher temperature thermostat may need to be fitted.
Using Apollo GEM
with Other Hot Water Heating Systems
Apollo GEM will work well with an existing gas or oil heating system. The more energy Apollo
GEM is able to deliver to the hot water system, the less energy will be needed by the normal hot
water system. On summer days it is possible that no energy will be used at all by the normal
heating system.
In order to give priority to the Apollo GEM system but to ensure that sufficient hot water is
always available it is recommended that the thermostat for the normal hot water system is set
below that of the Apollo GEM system but high enough to give an acceptable hot water
temperature.
e.g. if the Apollo GEM optimiser temperature is set for (say) 65
o
C, set the normal water heating
system thermostat for (say) 50
o
C or 55
o
C.
In this way if the water has been fully heated by Apollo GEM the normal water heating will be
“Held off” and if there was insufficient surplus energy available to heat the water to the normal
water temperature the normal hot water system will come on and “top up” to the required
temperature.
Apollo GEM
User Manual