2. When completed, downflow subbase, plenum, and furnace (or
coil casing when used) should be installed as shown in Fig. 6.
Step 4—Horizontal Attic Installation
Do not install the furnace on its back; safety control operation
will be adversely affected. Never connect return-air ducts to
the sides or back of the furnace. A failure to follow this
warning could result in fire, personal injury, or death.
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. 7.
CONSTRUCT A WORKING PLATFORM
Construct working platform on location where all required
furnace clearances are met. (See Table 1 and Fig. 7.)
INSTALL FURNACE
1. Position furnace in desired location.
2. Connect gas supply pipe. See Fig. 7 for typical piping entry.
3. Connect supply- and return-air ducts.
4. Install field-supplied filter retainers as indicated in Fig. 8 and
Table 3 before connecting return-air duct to furnace.
5. Install 24- X 24-in. sheet metal shield on platform in front of
louvered control panel as shown in Fig. 7.
Step 5—Horizontal Crawlspace Installation
The furnace can be installed horizontally with either the LH or RH
side up. In a crawlspace, the furnace can either be hung from the
floor joist or installed on suitable blocks or pad. 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 the horizontal crawlspace installation is very similar to the
attic, refer to Section IV. The installation of a sheet metal shield in
front of the louvered control panel is covered in Section IV. For a
crawlspace installation, this same sheet metal shield must be
installed above the louvered control panel. Extend the sheet metal
shield over the furnace top far enough to cover the gas pipe entry
hole.
Step 6—Filter Arrangement
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 the return-air duct has been connected to the furnace,
install the filters in a V-formation inside the return-air plenum. See
Fig. 8 and Table 3 for horizontal applications. Horizontal filter
retainers must be field supplied. See Fig. 9 for downflow applica-
tions.
Step 7—Gas Piping
Gas piping must be installed in accordance with national and local
codes. Refer to the NFGC NFPA 54-1992/ANSI Z223.1-1992.
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 4 for recom-
mended gas pipe sizing. Risers should be used to connect to the
furnace and to the meter.
If a flexible connector is required or allowed by the authority
having jurisdiction, black iron pipe shall be installed at the
gas valve and extend a minimum of 2 in. outside the furnace
casing.
Use the proper length of pipes to avoid stress on the gas
control manifold. A failure to follow this warning could result
in a gas leak causing fire, explosion, personal injury, or death.
Use a backup wrench at the furnace gas control when
connecting the gas pipe to the furnace to avoid damaging gas
controls or manifold.
Never purge a line into a combustion chamber. Never use
matches, candles, flame, or other sources of ignition to check
for gas leakage. Use a soap-and-water solution to check for
gas leaks. A failure to follow this warning could result in fire,
explosion, personal injury, or death.
Joint compounds (pipe dope) should be applied sparingly and only
to the male threads of the joints. This pipe dope must be resistant
to the action of propane gas.
Install an accessible manual shut-off valve upstream of the furnace
gas controls and within 72 in. of the furnace. A 1/8-in. NPT
plugged tapping is provided on the gas value for test gage
connection. Installation of an additional 1/8-in. NPT plugged
tapping, accessible for test gage connection, installed immediately
Fig. 6—Furnace, Plenum, and Subbase Installed on
a Combustible Floor
A78651
DOWNFLOW
SUBBASE
SHEET METAL
PLENUM
FURNACE
(OR COIL CASING
WHEN USED)
6
