The selection between cooling, cooling/glycol and ice mode are performed by the operator using the interface under
password. The switching between cooling and ice and heating modes will cause the unit shutdown and than the switching
between the two modes.
5.4 Setpoints management
The control is able to manage the evaporator leaving water temperature on the base of several inputs:
• Changing the setpoint from the keypad
• Switching between the main setpoint (set by keypad) and an alternative value (set by keypad to) on the base of a
digital input state (double setpoint function)
• Receiving a setpoint by a monitoring system or a BAS connected via serial line
• Resetting the setpoint of the base of analogic inputs
The control shows the source of the used (Actual) setpoint:
the main setpoint set by keypad is being used
the alternative setpoint set by keypad is being used
the setpoint is being reset by external input
The following setpoint reset methods are available to modify the local or double setpoint:
local or double setpoint are used on the base of the double setpoint digital input.
This is called “base setpoint”
base setpoint is modified on the base of an user analog input
base setpoint is modified on the base of outside ambient temperature (if available)
base setpoint is modified on the base of evaporator entering temperature
the setpoint sent by serial line is used
In the case of a failure in the serial connection or in the 4-20mA input the base setpoint is used. In case of a setpoint reset,
the system display will show the type of reset.
5.4.1 4-20mA setpoint override
The base setpoint is modified on the base of the value of the analog input and of a max reset value, as shown in the picture
below:
5.4.2 OAT setpoint override
To enable the OAT setpoint override the unit limiting control expansion board pCO
e
#2 is required, with the ambient sensor
installed. The base setpoint is modified on the base of outside ambient temperature and of a max reset value, of a value
of OAT to start reset and a value of OAT to apply max reset, as shown in the picture below:
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