Filters - Lennox SL280DFNV Installation Instructions Manual

Downflow Application
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or
alcove installations are shown in figure 14.
Downflow Application Installation Clearances
Left Side
Type of Vent
Connector
Top 1 in. (25 mm)
*Front 2-1/4 in. (57 mm)**
Back 1 in (25mm)
Sides 1 in. (25mm)
Vent 6 in. (152 mm)
Floor
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
** 3-1/4 in. if single wall vent pipe is used.
††The furnace may be installed on a combustible wood floor if an
optional additive base is installed between the furnace and the
combustible floor.
FIGURE 14
CAUTION
If this unit is being installed in a space serviced by
an exhaust fan, power exhaust fan, or other device
which may create a negative pressure in the space,
take care when sizing the inlet air opening. The
inlet air opening must be sized to accommodate the
maximum volume of exhausted air as well as the
maximum volume of combustion air required for all
gas appliances serviced by this space.
Top
Right Side
Air Flow
Bottom
Type C Type B1
1 in. (25 mm)
2-1/4in. (57 mm)
1 in (25mm)
1 in (25mm
1 in. (25 mm)
NC†† NC††
Improper installation of the furnace can result in
personal 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
plenum.
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.
Allow 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
property damage could result.

Filters

This unit is not equipped with a filter or rack. A field-pro-
vided high-velocity filter is required for the unit to operate
properly. Table 3 lists recommended filter sizes. A filter
must be in place any time the unit is operating.
If a highefficiency filter is being installed as part
of this system to ensure better indoor air quality,
the filter must be properly sized. Highefficiency
filters have a higher static pressure drop than
standardefficiency glass/foam filters. If the pressure
drop is too great, system capacity 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. Before using any filter with
this system, check the specifications provided by
the filter manufacturer against the data given in the
appropriate Lennox Product Specifications bulletin.
Additional information is provided in Service and
Application Note ACC002 (August 2000).
Cabinet Width
B (17-1/2")C
C (21")
Page 11
WARNING
IMPORTANT
TABLE 3
Return Air Filter Size (inches)
16 x 25 x 1 (1)
20 x 25 x 1 (1)