Emerson 3000 User Manual

The systems are designed for constant air delivery, therefore any unusual restrictions within the air 

circuit must be avoided. For under-floor air distribution, observe the following guidelines:

• Select the air supply grilles and perforated panels for the raised floor to ensure minimum loss of 

pressure in the circuit. Air volume dampers on grilles, which extend several inches below the 

surface of the raised floor, are usually detrimental to airflow.

• Consideration of the height of the damper on the grille in conjunction with the floor height will 

determine whether this type of grille may be used.

• The grilles used in raised floors vary in size, the largest being approximately 18" x 6" 

(457 x 152 mm). A larger grille size would be detrimental to the structural capacity of the raised 

floor panel. An 18" x 6" (457 x 152mm) heavy duty, pencil-proof type grille typically has 56 square 

inches (0.036 m

2

) of free area.

• Perforated panels are available from various manufacturers of raised floors. These panels are 

usually 2' x 2' (610 x 610mm) square and have a nominal free area of approximately 108 to 

144 square inches (0.07 to 0.09m

2

). Use caution in selecting perforated panels as some 

manufacturers have only 36 to 40 square inches (0.023 to 0.026m

2

) of free area, requiring four 

times as many panels.

• Avoid floor elevations below 7-1/2" (190.5mm), loosely installed flooring systems, and below-floor 

obstructions such as: electrical wiring chases, unusually long electronic system cables, or piping 

clusters.

• Always check specifications of the floor supplier before specifying the total number of perforated 

panels and grilles required to handle the air flow. The proper specifications for grilles and 

perforated panels should indicate the total free area required for air delivery rather than the 

number of panels and grilles. (See Table 3 for recommended free area required for each model.) 

This table indicates the recommended free area based on having the supply air grilles and 

perforated panels sized to handle approximately 75% of the total cubic feet per minute (CFM) of 

the units at a velocity of 550 to 600 ft./min. (2.8 - 3.1 m/s). The remaining 25% of the air flow in 

the raised floor passes through cable cutouts, cracks between the panels, and other leakage areas.

For ducted supply applications on upflow units, the duct work should be attached to the blower 

discharge flanges of the unit. For ducted return air applications, the duct work should be attached to 

the filter box flanges on upflow rear return units and on the unit top flange for downflow units. Refer 

to Figure 2 for information on upflow units and to Figure 3 for downflow units.
The duct work on upflow units must allow access to the motors/blowers for maintenance. The duct 

work on upflow units must be designed within the capacity of the unit, otherwise air flow and 

performance will be compromised.

A solid plenum or plenum with discharge grille(s) may be installed. The plenum and instructions for 

its installation ship separately from the unit.

3-ton 2.5 (0.01) 2.3 (0.01)  3-ton  2.5 (0.01) 2.3 (0.01) 
5-ton 3.5 (0.02) 3.3 (0.02)  5-ton  3.8 (0.02) 3.5 (0.02)