5 WORKING WITH THIS UNIT
5.1 Controller purpose
Then system will control the evaporator leaving water temperature to keep it at a setpoint value.
The system operates to optimize components performances from the point of view of their efficiency and of their duration.
The system assures a safe operation of the unit and of all components and prevents dangerous situations.
5.2 Unit enabling
The control allows different ways to enable/disable the unit:
• Keypad: Enter key on the keypad allows to switch between “Power OFF” mode and “Unit On” if other signals
allows this state
• Local Switch: when the digital input “Unit On/Off” is open the unit is in “Local switch Off”; when the digital input
“Unit On/Off” is closed the unit may be in “Unit On” or “Remote switch Off” on the basis of the “Remote On/Off “
digital input
• Remote Switch: when the local switch is On (“Unit On/Off” digital input closed) if the digital input “Remote On/Off
“ is closed the unit is in “Unit On”, when digital input “Remote On/Off “ is open the unit is in “Remote switch Off”
• Network: a BAS or a Monitoring system may send an On/Off signal trough the serial line connection to put the
unit on or in “Rem. Comm. Off”
• Time schedule : a timetable allows to program “Time Schedule Off” on a week base; several holiday days are
include.
• Ambient LockOut : the unit is not enabled to operate unless the ambient temperature is higher than an adjustable
value (default 15.0°C (59.0 F) )
To be in “Unit On” all the allowed signals must enable the unit.
5.3 Unit modes
The unit is able to work in the following modes:
• Cooling. When this mode is selected the control will operate to cool the evaporator water; the setpoint range is +4.0
+14.0 °C, (39.2 57.2 F) a freeze alarm setpoint is set to 2 °C (34.6 F) (adjustable by the operator in the range +1
+3 °C (33.8 37.4 F) ) and a freeze prevent setpoint is set to 3 °C (37.4 F) (adjustable by the operator in the range:
“freeze alarm setpoint” + 1 +3 °C (“freeze alarm setpoint” + 1.8 F 37.4 F) ).
• Cooling/Glyco. When this mode is selected the control will operate to cool the evaporator water; the setpoint range
are -8°C +14.0°C (17.6 57.2 F) , a freeze alarm setpoint are set to –10 °C (14.0 F) (adjustable by the operator
in the range –12 °C -9°C (10.4 15.8 F) ) and a freeze prevent setpoint are set to –9 °C (15.8 F) (adjustable by the
operator in the range “freeze alarm setpoint” + 1°C -9 °C (“freeze alarm setpoint” + 1.8 F 15.8 F))
• Ice. When this mode is selected the control will operate to cool the evaporator water; the setpoint range are -8°C
+14.0°C (17.6 57.2 F) , a freeze alarm setpoint are set to –10 °C (14.0 F) (adjustable by the operator in the range
–12 °C -9°C (10.4 15.8 F) ) and a freeze prevent setpoint are set to –9 °C (15.8 F) (adjustable by the operator in
the range “freeze alarm setpoint” + 1°C -9 °C (“freeze alarm setpoint” + 1.8 F 15.8 F)). While working in ice mode
compressors are not be allowed to unload but are stopped using a step procedure (se § 5.5.1)
• Heating. When this mode is selected the control will operate to heat the evaporator water; the setpoint range is +30
+45°C (86 113°C), a hot water alarm setpoint are set to 50°C (adjustable by the operator in the range +46 +55°C
(114.8 131 F) ) and a hot prevent setpoint are set to 48°C (118.4 F) (adjustable by the operator in the range +46°C
“hot water alarm setpoint” + 1°C (114.8 F “hot water alarm setpoint” + 1.8 F)).
• Cooling + Heat Recovery. Setpoints and freeze protection are managed as described in the cooling mode; in addition
the control will enable the heat recovery input and outputs foreseen on the expansion #2
• Cooling/Glycol + Heat Recovery. Setpoints and freeze protection are managed as described in the cooling/glycol
mode; in addition the control will enable the heat recovery input and outputs foreseen on the expansion #2.
• Ice + Heat Recovery. Setpoints and freeze protection are managed as described in the ice mode; in addition the
control will enable the heat recovery input and outputs foreseen on the expansion #2.
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