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*Gas connector may be
used for Canadian
able by local authority
having jurisdiction.
*GAS CONNECTION
RAISED
PLATFORM
SERVICE PLATFORM
INTAKE PIPE
EXHAUST PIPE
Figure 19
Return Air -- Horizontal Applications
Return air may be brought in only through the end of a
furnace installed in the horizontal position. The furnace is
equipped with a removable bottom panel to facilitate in-
stallation. See Figure 15.
Filters
-
IMPORTANT
and performance may be reduced.
The pressure drop may also cause the limit to trip more
frequently during the winter and the indoor coil to freeze
in the summer, resulting in an increase in the number of
service calls.
the data given in the appropriate Lennox Product
in Service and Application Note ACC002
(August 2000).
TABLE 1
Furnace
Cabinet Width
Filter Size
Side Return Bottom Return
17-1/2” 16 X 25 X 1 (1) 16 X 25 X 1 (1)
21” 16 X 25 X 1 (1) 20 X 25 X 1 (1)
24-1/2” 16 X 25 X 1 (2) 24 X 25 X 1 (1)
Duct System
Use industry-approved standards to size and install the
supply and return air duct system. Refer to ACCA Manual
D. This will result in a quiet and low-static system that has
uniform air distribution. See below for proper duct instal-
lation.
HORIZONTAL UNIT
SUPPLY
AIR
SUPPLY
AIR
Install self tapping screws
to seal any potential air
leaks
UPFLOW UNIT
NOTE - This furnace is not certied for operation in heat-
ing mode (indoor blower operating at selected heating
speed) with an external static pressure which exceeds 0.8
inches w.c. Operation at these conditions may result in
improper limit operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a remov-
able access panel should be installed in the supply air
duct. The access panel should be large enough to per-
mit inspection of the heat exchanger. The furnace access
panel must always be in place when the furnace is oper-
ating and it must not allow leaks. In horizontal units, in-
stall self tapping screws in the three evaporator coil screw
the vestibule panel.
Return Air Plenum
NOTE - Return air must not be drawn from a room
where this furnace, or any other gas-fueled appliance
(i.e., water heater), or carbon monoxide-producing de-
vice (i.e., wood replace) is installed.
When return air is drawn from a room, a negative pressure
is created in the room. If a gas appliance is operating in
pulled back down the vent pipe and into the room. This
-
bustion and the formation of carbon monoxide gas. This
raw gas or toxic fumes might then be distributed through-
out the house by the furnace duct system.
Return air can be brought in through the bottom or either
side of the furnace (return air brought into either side of
with bottom return air is installed on a platform, make an
airtight seal between the bottom of the furnace and the
platform to ensure that the unit operates properly and
-
lent sealing method between the plenum and the furnace
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