Figure - Lennox G40UH Series Installation Instructions Manual

This furnace may be installed in either an attic or a crawl-
space. Either suspend the furnace from roof rafters or
floor joists, as shown in figure 12, or install the furnace on
a platform, as shown in figure 13. The unit must be sup-
ported at both ends and beneath the blower deck to pre-
vent sagging.
NOTE − In horizontal applications, the unit must be lev-
el side to side. The unit may be tilted back to front a maxi-
mum of 1". This will ensure proper draining of the heat ex-
changer.
Typical Horizontal Application
Unit Suspended in Attic or Crawlspace
Leave sufficient clearance between rod and unit to
remove access panel.
1/4 in. ROD
ANGLE
IRON
U−CHANNELS

FIGURE 12

NOTE − Heavy gauge perforated sheet metal straps
(plumbers' straps) may be used to suspend the unit from
roof rafters or ceiling joists. When straps are used to sus-
pend the unit in this way, support must be provided for both
the ends and the middle of the furnace to prevent sagging.
The straps must not interfere with the plenum or exhaust
piping installation. Securing screws should be 1/2 inch
from the top edge and 1−1/2 inch from the side edge in all
cases. Cooling coils and supply and return air plenums
must be supported separately.
NOTE − When the furnace is installed on a platform in a
crawlspace, it must be elevated enough to avoid water
damage and to allow the evaporator coil to drain.
Return Air −− Horizontal Applications
Return air can be brought in through the end of a furnace
installed in a horizontal application. The furnace is
equipped with a removable bottom panel to facilitate
installation. See figure 9.
Horizontal Application
Unit Installed on Platform
NOTE − Line contact is permis-
sible. See the unit nameplate for
clearances.
WORKING
PLATFORM
Improper installation of the furnace can result in per-
sonal injury or death. Combustion and flue products
must never be allowed to enter the return air system
or the living space. Use screws and joint tape to seal
the return air system to the furnace.
In platform installations with bottom return air, the
furnace should be sealed airtight to the return air ple-
num. A door must never be used as a portion of the
return air duct system. The base must provide a
stable support and an airtight seal to the furnace. Al-
low absolutely no sagging, cracks, gaps, etc.
The return and supply air duct systems must never
be connected to or from other heating devices such
as a fireplace or stove, etc. Fire, explosion, carbon
monoxide poisoning, personal injury and/or proper-
ty damage could result.
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal inju-
ry or death.
Page 11
GAS
ENTRY
FIGURE 13
WARNING
WARNING
VENT
PIPE