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Mode
Description
Unit Range
Pursuit
Set in case of double water control cool and contemporary heat. Evaporator leaving water
temperature follows the Cool LWT 1 setpoint. Condenser leaving water temperature follows the
Heat LWT 1 setpoint.
W/C
Test
Enables the Manual Control of the unit. The manual test feature helps in debugging and checking
the operational status of sensors and actuators. This feature is accessible only with the
maintenance password in the main menu. To activate the test feature is required to disable the
Unit from the Q0 switch and change the available mode to Test (see section 5.2.2).
A/C and W/C
It has to be noted that in case the selected mode cannot be managed by the unit, it will revert to Cool.
Temperature Settings
Purpose of the unit is to keep the evaporator leaving water temperature as close as possible to a pre -set value, called
Active Setpoint. The Active Setpoint is calculated by the unit controller based on the following parameters:
•
Available Modes
•
Double setpoint input
•
Scheduler state
•
LWT Setpoint
•
Setpoint Reset
Operation mode and LWT setpoint can also be set via network if the appropriate control source has been selected.
5.1.3.1
LWT Setpoint Setting
Setpoint range is limited according to the selected operating mode. The controller includes:
•
two set points in cooling mode
•
two set points in heating mode (W/C units only))
•
one set point in ice mode
The above setpoints are activated according to Operating mode, Double Setpoint or Scheduler selection. If the Time
Scheduler is enabled the Double Setpoint input state will be ignored by the controller.
The table below lists the LWT Setpoint being activated according to the operation mode, the double setpoint switch status
and the scheduler state. The table also reports the defaults and the range allowed for each setpoint.
Operating Mode
Units
Double
Setpoint
Input
Scheduler
LWT Setpoint
Default
Range
Cool
W/C
OFF
Off, On Setpoint 1
Cool LWT 1
7.0°C
4.0°C
15.0°C
ON
On Setpoint 2
Cool LWT 2
7.0°C
4.0°C
15.0°C
Heat
W/C
OFF
Off, On Setpoint 1
Heat LWT 1
45.0°C
30.0°C
55.0°C(*)
ON
On Setpoint 2
Heat LWT 2
45.0°C
30.0°C
55.0°C(*)
The LWT setpoint can be overridden in case the setpoint reset (for details see chapter 5.1.4.3).
5.1.3.2
Thermostat Control Settings
Thermostat control settings, allows to set up the response to temperature variations and the precision of the thermostat
control. Default settings are valid for most applications, however site specific conditions may require adjustments in order
to have a smooth and precise temperature control or a quicker response of the unit.
The control will start the first circuit if the controlled temperature is higher (Cool Mode) or lower (Heat Mode) than the active
setpoint (AS) of at least a Start Up DT (SU) value. Once circuit capacity exceeds the
Hi Ld Stg Up %
another circuit is
switched on. When controlled temperature is within the deadband (DB) error from the active setpoint (AS), unit capacity
will not be changed.
If the leaving water temperature decreases below (Cool Mode) or rises above (Heat Mode) the active setpoint (AS), unit
capacity is adjusted to keep it stable. A further decreasing (Cool Mode) or increasing (Heat Mode) of the controlled
temperature of the Shut Down DT offset (SD) can cause circuit shutdown.
In the Shutdown area the whole unit is switched off. In particular, a compressor will be shut down if it is required to unload
below the
Lt Ld Stg Dn %
capacity.
Loading and unloading speeds are calculated by a proprietary PID algorithm. However, maximum the rate of water
temperature decrease can be limited through the parameter
Max Pulldn
.
Circuits are always started and stopped to guarantee the balancing of running hours and number or
starts in multiple circuits units. This strategy optimizes the lifetime of compressors, inverters,
capacitors and all the others circuit components.
