NOTE: Depending on the type of economizer with your system, all of the options listed may not be available on your
Vertiv™ Liebert® iCOM™ display.
Fluid Economizer Set Up Options
DT Between Room and Fluid Type
Selects the glycol/chilled water temperature input used by the comparator circuit to determine if the DT warrants use
of secondary cooling.
• Disabled: Disables the second cooling source in dual cool configurations and is the default setting for standard,
compressorized units and for chilled water units without a second cooling source.
• Contact: An external input is used to determine secondary cooling activation based on the open/closed status of
the contact:
Open: Activate second cooling source.
Closed: Deactivate second cooling source.
• Temp: The difference between the fluid temperature and the room air temperature (Temperature Setpoint)
determines use of secondary cooling. (The difference parameter is set with the DT between room and fluid value
slider. When the difference is equal to or greater than the selected value, secondary cooling is used.)
• Set: Enables free cooling when the sensed fluid temperature is colder than the Temperature Setpoint. (The
difference parameter is set using the DT between room and fluid value slider. When the difference is equal to or
greater than the selected value, secondary cooling is used.)
DT Between Room and Fluid Value
Temperature difference between fluid and room air at which secondary cooling activates. For example, when set at the
factory default 12°F (–11.1°C), secondary cooling activates when the fluid temperature is 12 or more degrees colder than
the room air temperature/setpoint.
Minimum CW Temp
Enables/disables setting a minimum chilled water temperature that controls simultaneous operation of chilled water
secondary cooling and compressor(s).
Minimum CW Temp Value
Temperature of the fluid that determines whether or not secondary cooling and compressor(s) operate simultaneously:
• If the fluid temperature is below the minimum temperature and if the temperature differential is satisfied (DT
between room and fluid value), then the compressor(s) are locked out and the secondary chilled-water coil
provides cooling.
NOTE: If secondary cooling fails (for example, loss of water flow), this setting is overridden and the compressor(s)
activated. If this occurs, free cooling is locked out for one hour.
• If the fluid temperature is above the minimum temperature, chilled water and the compressorized cooling will
operate simultaneously if needed.
Enable Free Cooling Flush
Number of hours between flushes of the free cooling coil.
7 Configuring Economizer Operation
111
Vertiv™ Liebert® iCOM™Installer/User Guide
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