User manual

Operation
Liebert
®
iCOM
®
40
Out of Service
When the Liebert Air Economizer
™
is not operating, the outside air damper is closed, the return air
damper is open and the relief air vent fan is shut down. This permits air from the conditioned space to
be drawn into the primary cooling unit, cooled and expelled into the conditioned space. The relief air
vent is not required while the Liebert Air Economizer is not in service because no air volume is being
brought into the conditioned space.
NOTICE
When a non-Liebert mixing box and damper motors are used, make sure that the following
configurations are verified before a unit is placed into service.
• No power to Liebert unit means that there is no power applied to the Liebert Air
Economizer damper motors. Without a spring return motor, the dampers will remain in the
last position they were in when power was present. Spring return operation during a no-
power condition should always be verified at startup.
• While the Liebert Air Economizer is not operating, which could be due to the outdoor air
conditions, a manual lockout through the Liebert iCOM or a Unit Off state will result in
2VDC being present on the associated indoor and outdoor analog outputs. The 2VDC signal
must result in the outdoor damper being closed and return damper opened.
• During full Liebert Air Economizer operation, the Liebert iCOM will send 10VDC to the
return and outdoor damper which must open the outdoor damper and close the return damper
to its minimum position of 15%.
NOTICE
Risk of improper operation. Could cause frozen coils, resulting in degraded operation, water
leaks, equipment damage and building damage.
Failure to verify that the indoor and outdoor damper operation is correct could result in the
freezing of chilled water coils, condensation within the data center or a main fan overload.
3.4.3 Liebert Air Economizer Control Menu Settings
The Liebert Air Economizer control uses an outdoor temperature humidity sensor to detect when
outdoor conditions are within the operating range. The outdoor sensor can be monitored from the
Service/Economizer data menu on page 2 of 3 (see Figure 38).
The Liebert iCOM control is equipped with a series of setup parameters to allow limited adjustment
and monitoring of the Liebert Air Economizer’s dampers and sensor. To access these parameters from
the main unit screen:
1. Press the down arrow key until User Menu is displayed.
2. From the User Menu screen, press the right arrow key to enter the Service Menu.
3. Press the Enter key once in the Service Menu and use the arrows to navigate to the ECO icon on
the bottom row.
4. Once this icon is selected, press Enter.
The parameters for the Liebert Air Economizer are now viewable.
Liebert Air Economizer Status Screen
Parameters SA03 through SA06 of the Liebert Air Economizer screen will show the current status of
the Liebert Air Economizer control. The Liebert Air Economizer will be activated for use if:
• All temperatures and ratios are within the outdoor sensor range
• The outdoor air is cooler than the indoor return air temperature.
Whether the Liebert Air Economizer function is available will be shown at parameter SA07—
Economizer Mode (On or Off).
The Liebert Air Economizer control allows the range of outdoor air acceptable for cooling to be
narrowed by adjusting the Humidity Ratio Min and Max settings. Refer to a psychrometric chart
before adjusting humidity ratios.