Liebert 50 & 60Hz - Manual (Page 27)

Site Preparation and Installation
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2.5 Indoor Air-Cooled Centrifugal Fan Condensing Unit Installation
2.5.1 Location Considerations
The centrifugal fan air-cooled condensing unit may be located above the dropped ceiling or any remote
indoor area. If noise is of concern, the condensing unit should be located away from personnel. Normal
operating sound may be objectionable if the condensing unit is placed near quiet work areas.
To mount the unit in the ceiling, refer to 2.4 - Installing the Evaporator or Chilled-Water Units
for hanging guidelines and to Figure 13 for dimensional data.
2.5.2 Ducting
Fan operation is designed for 5000 CFM (8495 CMH) at 0.5" external static pressure.
General Considerations
Use flexible duct work or nonflammable cloth collars to attach duct work to the unit and to control
vibration transmission to the building. Attach the duct work to the unit using the flanges provided.
Locate the unit and duct work so that the discharge air does not short circuit to the return air inlet.
Duct work that runs through a conditioned space or is exposed to areas where condensation may
occur must be insulated. Duct work should be suspended using flexible hangers. Duct work should not
be fastened directly to the building structure.
For multiple unit installations, space the units so that the hot condensing unit exhaust air is not
directed toward the air inlet of an adjacent unit.
Considerations for Specific Applications
In applications where the ceiling plenum is used as the heat rejection domain, the discharge
air must be directed away from the condensing unit air inlet and a screen must be added to the end of
the discharge duct to protect service personnel. Locate the air discharge a minimum of 4 feet from an
adjacent wall. Failure to do so may result in reduced air flow and poor system performance.
If the condensing unit draws air from the outside of the building, rain hoods must be
installed. Hood intake dimensions should be the same as the condensing unit duct dimensions. In
addition, install a triple layer bird screen over rain hood openings to eliminate the possibility of
insects, birds, water, or debris entering the unit. Avoid directing the hot exhaust air toward adjacent
doors or windows.