Emerson Liebert Economizer Solutions User Manual

DT between Room / Outdoor Type—Sets the activation point of the ambient dry bulb outdoor 

temperature as it relates to either an indoor actual temperature or temperature setpoint. If set to 

“Temp,” the outdoor dry bulb temperature is compared to the return temperature actual value. If set 

to “Set,” the outdoor dry bulb temperature is compared to the return temperature setpoint. If set to 

“Disable,” the outdoor temperature will not be compared to the return sensor value for activation. 

When set to “Temp” or “Set,” the outdoor temperature must be lower than the room temperature 

setpoint or the actual return temperature sensor reading..
In most applications, this parameter will be set to “Temp” because the outdoor air temperature will 

reduce cooling costs as long as the outdoor air is below the return air temperature to the primary 

cooling unit. This remains true even when the outdoor temperature is higher than the supply control 

setpoint. The following examples assume that the unit is set for supply air control and that the 

moisture content of the outdoor air is within the allowable range.
Example 1

• Return Temperature: 90°F (32°C)
• Outdoor Temperature: 80°F (27°C)
• Supply Air Temperature: 60°F (16°C)

The conditions in this example would result in a reduction of 10°F entering the unit and would 

extend the operating range of the Liebert Air Economizer. The outdoor damper would be 100% 

open and the mechanical cooling would be utilized to achieve the 60°F (16°C) supply temperature 

setpoint.

• Return Temperature: 75°F (24°C)
• Outdoor Temperature: 80°F (27°C)
• Supply Air Temperature Setpoint: 60°F (16°C)

In this example, the cooling unit would not use outdoor air because it is warmer than the actual 

return temperature to the CRAC.

• Return Temperature: 75°F (24°C)
• Outdoor Temperature: 40°F (4°C)
• Supply Air Temperature: 60°F (16°C)

In this example, the cooling unit would open the outdoor damper based on the amount of cooling 

needed to satisfy the supply air temperature setpoint. The unit should be able to satisfy the sup-

ply air setpoint with Liebert Air Economizer operation only.

SETPOINTS (pg 4 of 6)

to change parameter

to confirm

to select parameter

for next/previous unit
then 

UNIT   01

PASSWORD   (Actual Level  0)

????

DT between Room / Outdoor Type

Disable

DT between Room Air / Outdoor

°F

DT between Room / FC Type

Disable

DT between Room Air FC Fluid

°F

Minimum CW Temp

Disable

Minimum CW Temp Value

°F

Lockout FC at FC Fluid below

48°F

Transition Change

100 .0%

S134
S135
S136
S137
S138
S139
S140
S141
S142
S143
S144