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7.5 Centrifugal Air-Cooled Condensing Units
7.5.1 Installing the Indoor Condensing Unit
Refer to drawings for unit dimensions and component locations.
The indoor condensing unit is usually mounted above the ceiling and must be securely mounted to the
roof structure. The ceiling and ceiling supports of existing buildings may require reinforcements. Be
sure to follow all applicable codes. Use field-supplied threaded suspension rods and 3/8"-16 factory
hardware kit.
The indoor condensing unit must be located at the same level or above the Liebert Challenger 3000
unit. It must NOT be located below the Liebert Challenger 3000.
Recommended clearance between ceiling grids and building structural members is unit height plus
three inches.
Install the four field-supplied rods by suspending them from suitable building structural members.
Locate the rods so that they will align with the four mounting holes in the flanges that are part of the
unit base.
Using a suitable lifting device, raise the unit up and pass the threaded rods through the four mount-
ing holes in the flanges that are part of the unit base.
Attach the threaded rods to the unit flanges using the supplied nuts and grommets. (See Figure 35 -
Detail of ceiling hanging bracket, Threaded Rod and Hardware Kit Installation). The rubber
grommets provide vibration isolation.
1. Use the plain nuts to hold unit in place. Adjust these nuts so that the weight of the unit is
supported evenly by the four rods, does not rest on the ceiling grid, and is level.
2. Use the Nylock nuts to “jam” the plain nuts.
!
WARNING
Risk of heavy unit falling from supports. Can cause equipment and building damage, injury
and death.
Be sure the supporting roof structure is capable of supporting the weight of the unit(s) and
the accessories during installation and service. (See Table 30 - Indoor centrifugal
condensing unit.)
Be sure to securely anchor the top ends of the suspension rods. Make sure all nuts are tight.
NOTE
The units must be level in order to operate properly.
Table 30 Indoor centrifugal condensing unit
Model
Net Weight
lb (kg)60 Hz 50 Hz
MC_40A MC_39A 240 (109)
MC_65A MC_64A 449 (204)