Elevating Ahu For Gravity Floor Drain Connections; Duct Connections; Duct Connection Guidelines; Flanged Duct Or Sleeves - Pace PAI Installation And Assembly Manual

PACE │ Installation & Assembly Manual

Figure 155 - Combining Drain Lines

If the distance from the drain pan outlet to the trap
exceeds 10 ft, install additional clean outs for each 10
ft segment of horizontal drain line (min. 1/4 in per foot
fall required). On initial start-up, it may be necessary to
fill the trap manually.
Elevating AHU for Gravity Floor Drain
Connections
On indoor AHUs, the installer must provide a method
to pump or drain the coil condensate water away from
the AHU. The installer may have to elevate the AHU to
provide space below the condensate drain of the AHU
to properly install the designed drain trap(s) to permit
gravity flow of condensate water from the drain pan as
shown in Figure 14 on page 26.

DUCT CONNECTIONS

The duct must have positive seal to the AHU openings.
Outdoor base rails are available in 3, 6, 8, or 10 in.
height. It's the contractor's responsibility to provide the
ductwork, which includes the base rail height, and sup-
port it independently from the AHU.

Duct Connection Guidelines

The duct connection guidelines are as follows:
• Duct connections to the AHU may be made di-
rectly except when the AHU has external isola-
tion. Then the duct connections should be made
with flexible material, and be installed so they are
sufficiently loose.
• Duct connections should be designed and in-
stalled according to AMCA Standards 200 and
201, at a minimum.
• Duct turns and transitions must be made care-
fully to hold friction loss to a minimum. Avoid short
turns. Duct elbows should contain splitters or turn-
ing vanes.
Issue Date: 07/03/2018
SECTION 3 - HANDLING, STORAGE, AND INSTALLATION
• The effective duct length connected to the fan or
AHU discharge should run in a straight line for at
least 2.5 equivalent discharge diameter for up to
2500 FPM fan outlet velocity and one additional
diameter for each additional 1000 FPM fan outlet
velocity.
• Ductwork should be no greater than 105.5% or no
less than 85.5% of the discharge area. The slope
LD06345
of the transition elements should not be greater
than 15% for converging elements, or greater
than 7% for diverging elements.
• To find the equivalent discharge diameter, use
the following equation, where a = height, and b =
width of the discharge:
• A duct turn should be in the same direction as the
fan rotation as shown in Figure 156 on page 94.
Never deadhead the discharge into the flat sur-
face of a plenum.
Note: Make Turns In
The Same Direction
As Fan Rotation
Turning Vanes
Figure 156 - Recommended Discharge Duct
Arrangement when Turns are Required

Flanged Duct or Sleeves

To use flanged ducts or sleeves, make sure there is
access on all four sides to fasten the flange completely.
Connect the flanged ducts with self-drilling screws
directly to the AHU with a gasket or sealant between
the AHU, and the duct flange as shown in Figure 157
on page 95. A flange may be dropped through the
opening, if there is access to seal and fasten the flange
to the AHU's interior surface.
94
EDD = 4ab/�
Effective Duct Length
Air
Flow
Air
Flow
Form PA102.20-N1
Air
Flow
LD06335