Operating instructions
supply/outlet or air conditioning coil casing (when used). DO NOT
cut main furnace casing to attach supply side air duct, humidifier,
or other accessories. Allaccessories MUST be connected external
to furnace main casing.
D. Return Air Connections
UPFLOW FURNACES
The return-air duct must be connected to bottom, sides (left or
right), or a combination of bottom and side(s) of main furnace
casing as shown in Fig. 1. Bypass humidifier may be attached into
unused side return air portion of the furnace casing. DO NOT
connect any portion of return-air duct to back of furnace casing.
DOWNFLOW AND HORIZONTAL FURNACES
The return-air duct must be connected to return-air opening
provided as shown in Fig. 1. DO NOT cut into casing sides or back
to attach any portion of return-air duct. Bypass humidifier connec-
tions should be made at ductwork or coil casing sides exterior to
furnace.
IV. SUPPLY AIR PLENUM INSTALLATION (DOWN-
FLOW)
A. Downflow Installation
NOTE: This furnace is approved for use on combustible flooring
when manufacturer’s accessory floor base Part No.
KGASB0201ALL is used. Manufacturer’s accessory floor base is
not required when this furnace is installed on manufacturer’s Coil
Assembly Part No. CD5 or CK5, or Coil Box Part No. KCAKC is
used.
1. Determine application being installed from Table 3.
2. Construct hole in floor per dimensions specified in Table 3
and Fig. 5.
3. Construct plenum to dimensions specified in Table 3.
4. If downflow subbase (KGASB) is used, install as shown in
Fig. 6.
If coil assembly CD5, CK5, or Coil Box KCAKC is used,
install as shown in Fig. 7.
B. Installation On Combustible Floor
1. Cut and frame hole in floor per dimensions in Installation
Instructions packaged with downflow subbase.
2. When completed, downflow subbase, plenum, and furnace
(or coil casing when used) should be installed as shown in
Fig. 6.
V. HORIZONTAL ATTIC INSTALLATION
The furnace can be installed horizontally on either the left-hand
(LH) or right-hand (RH) side. A typical attic installation is shown
in Fig. 9.
A. Construct Working Platform
Construct working platform on location where all required furnace
clearances are met. (See Table 1 and Fig. 9.)
B. Install Furnace
Position furnace in desired location.
3. Connect gas supply pipe. See Fig. 9 for typical piping entry.
4. Connect supply- and return-air ducts.
5. Install field-supplied filter retainers as indicated in Fig. 12
and Table 4 before connecting return-air duct to furnace.
6. Install 24- X 24-in. sheet metal shield on platform in front
of louvered control panel as shown in Fig. 9.
VI. HORIZONTAL CRAWLSPACE INSTALLATION
The furnace can be installed horizontally with either the LH or RH
side up. In a crawlspace, furnace can either be hung from floor
joist (see Fig. 10) or installed on suitable blocks or pad. (See Fig.
11.) The furnace can be suspended from each corner by hanger
bolts (4 each 3/8-in. all-thread rod) cut to desired length, 1- X
3/8-in. flat washer, 3/8-in. lockwasher, and 3/8-in. nut. Dimples
are provided for hole locations. (See Fig. 1.)
Since horizontal crawlspace installation is very similar to attic
installation, refer to Step 4. The installation of a sheet metal shield
in front of louvered control panel is covered in Step 4. For a
crawlspace installation, this same sheet metal shield must be
installed above louvered control panel. Extend sheet metal shield
over furnace top far enough to cover gas pipe entry hole.
VII. FILTER ARRANGEMENT
WARNING: Never operate unit without a filter or with
filter access door removed. A failure to follow this
warning could result in fire, personal injury, or death.
The 2 factory-supplied filters are shipped in the blower compart-
ment. After return-air duct has been connected to furnace, install
filters in a V-formation inside return-air plenum. See Fig. 12 and
Table 4 for horizontal applications. Horizontal filter retainers must
be field supplied. See Fig. 13 for downflow applications.
VIII. GAS PIPING
Gas piping must be installed in accordance with national and local
codes. Refer to the NFGC NFPA 54-1999/ANSI Z223.1-1999.
Canadian installations must be installed in accordance with NSC-
NGPIC and all authorities having jurisdiction.
The gas supply line should be a separate line directly from the
meter to the furnace, if possible. Refer to Table 5 for recom-
mended gas pipe sizing. Risers should be used to connect to the
furnace and to the meter.
CAUTION: If flexible connector is required or allowed
by authority having jurisdiction, black iron pipe shall be
installed at gas valve and extend a minimum of 2 in.
outside furnace casing.
CAUTION: Use a backup wrench at furnace gas control
when connecting gas pipe to furnace to avoid damaging
gas controls or manifold.
TABLE 2—FREE AREA OF COMBUSTION AIR OPENING
331AAV
FURNACE
HIGH-FIRE
INPUT
(BTUH)
AIR FROM UNCON-
FINED 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)
63,000 100 15.8 5 31.5 7 21.0 6
84,000 100 21.0 6 42.0 8 28.0 6
105,000 105 26.3 6 52.5 9 35.0 7
123,000 123 30.8 7 61.5 9 41.0 8
—7—