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The AS02 unit features an in-line immersion heater built inside the casing to boost the heating
water. If this built-in immersion is to be used, parameter R12 should be set to 1 (Water Line).
This immersion will then become active when all of the following conditions are met:
The Ambient Temperature is less than 4°C.
The Inlet Water Temperature is 7°C less than the Target Temperature.
The compressor has been at maximum output (> 80Hz) for more than 30 minutes.
The water pump has been running for at least 1 minute and flow is detected.
This immersion will then switch off when any of the following conditions are met:
The Ambient Temperature rises to more than 2°C.
The Inlet Water Temperature rises to 2°C less than the Target Temperature.
The compressor outputs drops below the medium output (< 50Hz).
Flow is no longer detected.
If this built-in immersion is not to be used, parameter R12 should be set to 0 (Not Used) or 2
(Water Tank) if a cylinder immersion is to be controlled
The rating of the AS02 will increase from 18Amps to 32Amps due to the power consumption of
this immersion when it is activated. It is essential to ensure the supply to the unit is adequate
as detailed in section 3.10.1.
RO 11 Alarm – This output (230Vac) can be used to trigger a light or buzzer to indicate that
there is an error/alarm situation. This is useful if the controller is not in an occupied space.
RO 12 Auxiliary Pump – This output is for controlling an auxiliary pump which may be used to
boost either the heating flow rate if the system has high pumping losses or an auxiliary DHW
pump. This output is protected with a 3 Amp fuse.
RO 10 3 Way Valve – This output is for controlling a 3-port motorised valve. This output will
become active when the unit is in DHW mode and will remain active until the unit returns to
heating mode, cooling mode or standby mode. The output will activate the 3-port motorised
valve diverting flow from the heating circuit to the DHW cylinder. Please see section 3.9 for
more details. A permanent live connection is also supplied to supply the power to return the
pump to the heating position when the units exits DHW mode. Both the permanent live and the
3 way valve output are protected by a 3 Amp fuse.
3.10.4 Temperature Sensors
There is one additional temperature sensor which needs to be connected to the unit in order to
achieve full functionality. This sensor is a DHW storage temperature sensor. The sensor is
supplied with the unit but the wiring to it may need to be extended. The wires should be ran
separately to any power transmission cables, however, if they need to run close to or in the
same conduit as power transmission cables, then shielded cable should be used. The type of
temperature sensor to be used is NTC 10kΩ.
The DHW storage temperature sensor is used to control the DHW heating requirements. It
must be connected or this will cause a fault and trigger an alarm. The unit will arrive with a link
wire compete with a built-in resistor in order to give a reading and enable the unit to operate.
The link wire which is wired into the ‘TT’ terminals of the installer’s wiring enclosure needs to be
removed and replaced with the supplied DHW storage temperature sensor. The sensor should
be located in a stat pocket on the DHW storage cylinder to give an accurate indication of the
cylinder’s temperature. If the unit is only to be used for space heating, the link wire complete
with resistor should not be removed from the ‘TT’ terminals.
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