Step 2—Downflow Installation
NOTE:
For downflow applications, this furnace is approved for
use on combustible flooring when any one of the 3 accessories are
used:
•
Special Base, KGASB
•
Cased Coil Assembly Part No. CD5 or CK5
•
Coil Box Part No. KCAKC
1. Determine application being installed from Table 3.
2. Construct hole in floor per Table 3 and Fig. 11.
3. Construct plenum to dimensions specified in Table 3 and Fig.
11.
4. If downflow subbase, KGASB is used, install as shown in Fig.
12. If Coil Assembly Part No. CD5 or CK5 or Coil Box Part
No. KCAKC is used, install as shown in Fig. 13.
NOTE:
It is recommended that the perforated supply-air duct
flanges be completely folded over or removed from furnace when
installing the furnace on a factory-supplied cased coil or coil box.
To remove the supply-air duct flange, use wide duct pliers or hand
seamers to bend flange back and forth until it breaks off. Be careful
of sharp edges. (See Fig. 14.)
BOTTOM RETURN AIR INLET
These furnaces are shipped with bottom closure panel installed in
bottom return-air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel,
perform the following:
1. Tilt or raise furnace and remove 2 screws holding bottom filler
panel. (See Fig. 9.)
2. Rotate bottom filler panel downward to release holding tabs.
3. Remove bottom closure panel.
4. Reinstall bottom filler panel and screws.
Step 3—Horizontal Installation
Do not install the furnace on its back or hang furnace with
control compartment facing downward. Safety control opera-
tion will be adversely affected. Never connect return-air ducts
to the back of the furnace. Failure to follow this warning
could result in fire, personal injury, or death.
The furnace can be installed horizontally in an attic or crawl space
on either the left-hand (LH) or right-hand (RH) side. The furnace
can be hung from floor joists, rafters or trusses or installed on a
platform, non-combustible blocks, bricks or pad.
SUSPENDED UNIT SUPPORT
The furnace may be supported under each end with threaded rod,
angle iron or metal plumber’s strap as shown. (See Fig. 15 and 16.)
Secure angle iron to bottom of furnace as shown. Heavy-gauge
sheet metal straps (plumber’s straps) may be used to suspend the
unit from each bottom corner. To prevent screws from pulling out,
use 2 # 8 x ¾-in. screw into the side and 2 # 8 x ¾-in. screw in the
bottom of the furnace casing for each strap. (See Fig. 15 and 16.)
PLATFORM UNIT SUPPORT
Construct working platform at location where all required furnace
clearances are met. (See Fig. 2 and 17.) For furnaces with 1-in.
Table 2–Minimum Free Area of Combustion Air Opening*
FURNACE
INPUT
(BTUH)
AIR FROM INDOOR
UNCONFINED SPACE
OUTDOOR AIR THROUGH
VERTICAL DUCTS
OUTDOOR AIR THROUGH
HORIZONTAL DUCTS
OUTDOOR AIR THROUGH
SINGLE DUCT
Free Area
of Opening
(Sq In.)
Free Area of
Opening and Duct
(Sq. In.)
Round Pipe
(in. Dia)
Free Area of
Opening and Duct
(sq In.)
Round Pipe
(in. Dia)
Free Area of
Opening and Duct
(Sq In.)
Round Pipe
(In. Dia)
66,000
100
16.5
5
33
7
22.0
6
88,000
100
22.0
6
44
8
29.3
7
110,000
110
27.5
6
55
9
36.7
7
132,000
132
33
7
66
10
44.0
8
154,000
154
38.5
7
77
10
51.3
8
* Free area shall be equal to or greater than the sum of the areas of all vent connectors in the confined space. Opening area must be increased if other gas appliances
in the space require combustion air.
Fig. 9—Removing Bottom Closure Panel
A02098
Fig. 10—Leveling Legs
A02071
1
3
⁄
4
″
1
3
⁄
4
″
1
3
⁄
4
″
1
3
⁄
4
″
5
⁄
16
″
5
⁄
16
″
5
⁄
16
″
5
⁄
16
″
9
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