Liebert 50 & 60Hz Ducting, General Considerations, Considerations for Specific Applications

Site Preparation and Installation

2.5Indoor Air-Cooled Centrifugal Fan Condensing Unit Installation

2.5.1Location 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.

2.5.2Ducting

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.

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