Technical Specifications

Designing a Liebert XD Solution
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3.9 Liebert XDR Module Placement
The Liebert XDR does not require a hot aisle/cold aisle arrangement for effective and efficient
operation. Refer to site-specific drawings for exact placement.
The Liebert XDR is engineered to fit the rear of computer enclosure cabinets.
Ensure that there is 25.6" (649mm) clearance in the rear to allow the door to open fully.
3.9.1 Airflow
The server fans draw air into the equipment enclosure. After heated the air, the server fans force the
air across the Liebert XDR’s two coils. The Liebert XDR has a low air-side pressure drop (similar to a
rack with perforated doors). The server fans within the rack create sufficient airflow to move the air.
Figure 18 Generic airflow diagram
Efficient cooling of rack equipment depends on proper use of blanking plates in any voids in the rack
and good cable management. Refer to the user manual supplied with the rack where the Liebert XDR
is mounted. Keep the Liebert XDR’s coils clear of any obstructions that might block the airflow.
Each of the Liebert XDR’s coils removes approximately half the load. For even cooling in partially
filled racks, servers should be evenly spaced and blanking plates should be installed on unused rack
spaces to prevent recirculation of heated air. The top and bottom of the rack must be sealed with floor
and ceiling panels. Not installing the panels will drastically reduce the Liebert XDR’s performance.
Table 6 Calculating quantity of Liebert XDR modules
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/Liebert
DS unit sensible capacity, kW
D
E Required Liebert XD system cooling capacity, kW = C – D
F Number of Liebert XDR20s required = E ÷ 20, rounded up
G
Number of Liebert XDP/Liebert XDC modules required = F ÷ 8,
rounded up
Liebert XDR
Front
of
Rack
Rear
of
Rack
Refrigerant
Connections
Critical
Equipment
Enclosure /Rack
Shown from Side