Emerson Liebert Economizer Solutions User Manual

Liebert cooling units control the Liebert Air Economizer with the analog outputs of the Liebert iCOM 

control. The Liebert iCOM can be used with a Liebert Air Economizer or with a previously installed 

Liebert Air Economizer equipped with 0-10VDC or 2-10VDC dampers. The Liebert iCOM is capable of 

driving two independent damper motors or can be set up through the software to output a single 

signal where the dampers are inversely driven.
The primary cooling unit responds to sensors that monitor the temperature and humidity of the 

outdoor air, return air and supply air. If outdoor conditions are within the tolerances set, the primary 

cooling unit opens the Liebert Air Economizer’s dampers varying amounts to use outdoor air for 

cooling. When outdoor conditions are too warm or humid for cooling, the primary cooling unit closes 

the Liebert Air Economizer’s dampers, taking it out of the cooling process.

Risk of high or low humidity. Can cause environmental conditions that are outside equipment 

requirements.
While the Liebert Air Economizer is operating, the primary cooling unit’s humidification and 

dehumidification are inhibited. If humidity level is important to operational requirements, it 

must be controlled by other methods during operation of the Liebert Air Economizer. While 

the primary cooling unit is cooling without the Liebert Air Economizer, the primary cooling 

unit will control humidity levels according to its setpoints.

Risk of freezing temperatures. Can cause equipment and property damage.
Low outdoor temperatures can produce freezing conditions that adversely affect cooling 

systems employing water, particularly when the water is not moving through the pipes. When 

cooling system water is not moving, frozen waterlines, burst coils and water damage are 

possible. The outside damper must be set so that it is fully closed when freezing temperatures 

are possible and the cooling system is not operating (see 4.2.4 - Disable the Liebert Air 

Economizer). This can be achieved by either connecting a freeze stat that interrupts the 

economizer signal or by wiring a freeze stat directly into the Liebert iCOM’s customer input.
The risk of freezing is increased unless the proper amount of glycol is added to the chilled 

water unit loops.

Risk of infiltration of odors, smoke and particulates from outside air. Can cause 

environmental conditions that are outside equipment requirements.
The Liebert Air Economizer does not remove odors, smoke, gases or particulates from the 

outside air used for cooling. These must be controlled by other methods.