5750156-UIM-B-0919
6
Johnson Controls Ducted Systems
DUCTWORK
These units are adaptable to downflow use as well as rear supply and
return air duct openings. To convert to downflow, use the following
steps:
1.
Remove the duct covers found in the bottom return and supply air
duct openings.
2.
Install the duct covers (removed in step one) to the rear supply and
return air duct openings.
3.
Seal duct covers with silicone caulk.
Duct work must be designed and sized according to the methods of the
Air Conditioning Contractors of America (ACCA), as set forth in their
Manual D.
Use a closed return duct system. This does not preclude use of econo-
mizers or ventilation air intake. It is best practice to use flexible joints in
the supply and return duct work to minimize the transmission of vibra-
tion and noise.
See Figures 4 and 5 for information concerning rear and bottom supply
and return air duct openings.
FILTERS
Proper filter size is very important. Filter size, type, and pressure drop
must always be considered during duct system design.
Single phase units are shipped without a filter or filter racks. It is the
responsibility of the installer to secure a filter in the return air ductwork
or install a Filter/Frame Kit.
A filter rack and high velocity filters are standard on three phase units.
Always use filters and keep filters clean. When filters become dirt laden,
insufficient air is delivered by the blower, decreasing your unit’s effi-
ciency and increasing operating costs and wear-and-tear on the unit
and controls.
Check filters monthly. This is especially important because the unit is
used for both heating and cooling.
NOTICE
All units are shipped in the horizontal supply/return configuration. It is
important to reduce the possibility of any air leakage through the bot-
tom duct covers (resulting from cut, torn, or rolled gasket) due to
improper handling or shipping processes. To ensure a good tight
seal, it is recommended that silicone caulk and/or foil tape be applied
along the cover edges.
NOTICE
Be sure to note supply and return openings.
Model
A
B
C
D
E
F
24, 30, 36, 42
10
21.5
5
4.5
47.5
32
48, 60
14
13.5
5
3.5
47.5
42
FIGURE 4:
Bottom Duct Dimensions (in.)
Model
A
B
24, 30, 36, 42
9.6
22
48, 60
13.6
14
FIGURE 5:
Rear Duct Dimensions (in.)
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