Specifications
Designing a Liebert XD Solution
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3.8.2 Determining Vertical Placement of Liebert XDOs Above the Cold Aisle
In the maximum density configuration, Emerson recommends placing the Liebert XDOs between 18
and 24 inches (457-609mm) above the equipment cabinets. In some cases where the required density
is less, the front-to-rear spacing of Liebert XDOs in a row will be increased. To ensure coverage of the
wider spaces between the Liebert XDO units, the vertical distance between the cabinets and the Lie-
bert XDOs should be increased. However, the recommended maximum height of the Liebert XDO
above the cabinets is 30 inches (762mm). See Figure 18.
Figure 18 Liebert XDO placement over cold aisle
Table 5 can be used to determine the correct number and spacing of Liebert XDOs.
Table 5 Calculating quantity and spacing of Liebert XDO modules (example below is Liebert XDO20)
Input Information Step Result
Total heat load in the room, kW A
Reserve capacity needed
(10% to 25% of A is recommended)
B
C Required cooling capacity, kW = A + B
Existing/planned Liebert Deluxe/DS unit
sensible capacity, kW
D
E Required Liebert XD system cooling capacity, kW = C – D
F
Number of Liebert XDO20s required = E ÷ 20, rounded up (60Hz)
= E ÷ 16, rounded up (50Hz)
G
Number of Liebert XDP
/Liebert XDC modules required = F ÷ 8,
rounded up (60Hz and 50Hz)
Room area, square feet H
I Area served by each Liebert XDO20 = H ÷ F
Spacing of cold aisles, center-to-center,
typically 12-16 ft (3.7 to 4.9m)
J
K Spacing between each Liebert XDO = (I ÷ J) - 2
L
Required Liebert XD system cooling density = E x 1000 ÷ H
OK if under 640; otherwise, additional cooling is required from
Liebert Deluxe or Liebert DS units.
18-24"
(45.7-60.9mm)
30" max
18-24"
(45.7-60.9mm)
30" max
Hard-Piped
Connection
One -Shot
Connection
4' *
(1.2m)
3' *
(.91m)
4' *
(1.2m)
COLD AISLE
HOT AISLE
COLD AISLE
Cold Aisle
Spacing
* Nominal Distance
Cooled air
enters the
rack
Hot air goes
into the hot
aisle
Critical
Equipment
Critical
Equipment
Critical
Equipment
Critical
Equipment
Hot air goes
into the hot
aisle
Cooled air
enters the
rack
Hot air is
drawn into
the XDO for
cooling