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CONTROL
4. Control
4.1 Stop
Shutdown occurs for one of the following reasons:
A Abnormal shutdown: in order to protect the compressors and other components, if an abnormal state occurs
the system stops and an error code is displayed on the PCB digital displays and on the user interface.
B The system stops when the set temperature has been reached.
4.2 Standby
4.2.1 Compressor crankcase heater
The compressor crankcase heater is used to prevent refrigerant from mixing with compressor oil when the compressor
is stopped.
It is controlled according to the outdoor ambient temperature and the compressor on/o status.
When the outdoor ambient temperature is above 8°C or the compressor is in operation, the heater is o.
When the outdoor ambient temperature is at or below 8°C and either the compressor has been stopped for more than
3 hours or the unit has just been switched on (manually or when the power supply has returned following a power
failure), the heater switches on.
4.2.2 Water circulator
There are several cases depending on the type of control set on the unit:
1. Control of system water temperature:
- when the set point is reached, the internal circulator continues to run continuously
2. Control by ambient thermostat:
- when the set point is reached, the internal circulator stops
- when the set point is reached, the internal circulator switches on every 6 hours for 3 minutes
Note: the internal circulator operates continuously during defrosting and antifreeze operations.
4.3 Startup control
4.3.1 Delayed compressor startup
In initial startup control and in re-start control (except in oil return and defrosting operations), compressor activation is
delayed to allow a minimum time to elapse in order to prevent frequent compressor switching on/o and to equalise
the pressure within the refrigerant circuit. The compressor re-start delays for cooling and heating modes are set on the
user interface. Refer to the installation manual: Heating/cooling modes setting.
4.3.2 Compressor startup
In initial startup control and in re-start control, compressor activation is controlled according to outdoor temperature.
Compressor startup follows one of two startup programs until the set rotation speed is reached.
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