521271-UIM-D-1211
Johnson Controls Unitary Products
7
CRITICAL COIL PROJECTION
The coil assembly must be located in the duct such that a minimum dis-
tance is maintained between the top of the coil and the top of the duct.
Refer to Table 2.
COIL / FURNACE ASSEMBLY - HC SERIES COILS
These coils are supplied ready to be installed in a right hand position or
a left hand position. When used in conjunction with a horizontal furnace
(blow through) application, the coil should be oriented with the opening
of the “A” coil closest to the furnace. See Figure 7.
DOWNFLOW DUCT CONNECTORS
All downflow installations must use a suitable duct connector approved
by the furnace manufacturer for use with this furnace. The duct connec-
tors are designed to be connected to the rectangular duct under the
floor and sealed. Refer to the instructions supplied with the duct con-
nector for proper installation. Refer to the separate accessory parts list
at the end of these instructions for the approved accessory duct con-
nectors.
RESIDENTIAL AND MODULAR HOME UPFLOW
RETURN PLENUM CONNECTION
Return air may enter the furnace through the side(s) or bottom depend-
ing on the type of application. Return air may not be connected into the
rear panel of the unit.
SIDE RETURN APPLICATION
Side return applications pull return air through an opening cut in the
side of the furnace casing. This furnace is supplied with a bottom block-
off panel that should be left in place if a side return is to be used. If the
furnace is to be installed on a flat, solid surface, this bottom panel will
provide an adequate seal to prevent air leakage through the unused
bottom opening. However, if the furnace is to be installed on a surface
that is uneven, or if it is to be installed on blocks or otherwise raised off
the floor,
it will be necessary to seal the edges of the bottom panel
to the casing using tape or other appropriate gasket material to
prevent air leakage.
BOTTOM RETURN AND ATTIC INSTALLATIONS
Bottom return applications normally pull return air through a base plat-
form or return air plenum. Be sure the return platform structure or return
air plenum is suitable to support the weight of the furnace.
The internal bottom panel must be removed for this application.
Attic installations must meet all minimum clearances to combustibles
and have floor support with required service accessibility.
DOWNFLOW APPLICATION
For downflow applications, the furnace must be turned upside-down so
that the circulating air enters at the top and exits the furnace at the bot-
tom. The combustion air inducer must be rotated 90° as shown in Fig-
ure 21.
DO NOT BLOCK COMBUSTION AIR INLET OPENINGS.
HORIZONTAL APPLICATION
ATTIC INSTALLATION
Each coil is shipped with an external tie plate that should be used to
secure the coil to the furnace. It should be installed on the back side
of the coil using the dimpled pilot holes.
See Figure 7.
FIGURE 7:
Horizontal Left or Right application (Right Shown)
FIGURE 8:
Combustible Floor Base Accessory
NOTICE
Use tie plate
supplied with coil
Air flow
Gas Furnace
FURNACE
WARM AIR PLENUM
WITH 1” FLANGES
FIBERGLASS
INSULATION
FIBERGLASS TAPE
UNDER FLANGE
COMBUSTIBLE FLOOR
BASE ACCESSORY
FIGURE 9:
Horizontal Application
This furnace may be installed in a horizontal position on either side
as shown above. It must not be installed on its back.
FIGURE 10:
Typical Attic Installation
Return
Air
Sediment
Trap
Gas Piping
Supply
Air
Vent (Maintain
required
clearances to
combustibles)
Line contact only permissible
between lines formed by the
intersection of furnace top
and two sides and building
joists, studs or framing
12”
30” MIN.
Work Area
Filter rack
must be a minimum
distance
of 18” (45.7 cm)
from the
furnace
12”
Sheet metal in
front of furnace
combustion air
Openings is
Recommended
