035-17438-001 Rev. A (901)
Unitary Products Group
9
5.
Position the filter between the wire retainer and the cabi-
net wall (or floor) so it completely covers the cabinet air
opening and secure the filter in place at the front of the
cabinet by fastening the closed (looped) end of the
retainer wire under the flanged edge of the cabinet.
When properly installed the filter should fit flush with all
four sides of the cabinet wall.
NOTE:
Air velocity through throwaway type filters may not
exceed 300 feet per minute. All velocities over this require the
use of high velocity filters.
Side Return External Filter
Locate and knock out the square corner locators. These indi-
cate the size of the cutout to be made in the furnace side
panel, refer to Figure 4.
Install the side filter rack following the instructions provided
with that accessory. If a filter(s) is provided at another loca-
tion in the return air system, the ductwork may be directly
attached to the furnace side panel.
NOTE:
Some accessories such as electronic air cleaners
and pleated media may require a larger side opening
.
The return duct may be attached to the furnace by S-cleat,
bend tabs or other approved methods. Be sure to seal the
duct to the furnace to prevent air leakage.
In order to achieve the airflow indicated in the table, it is rec-
ommended for those applications over 1800 CFM use return
from two sides, one side and the bottom, or bottom only. For
bottom only application, see data and notes on blower perfor-
mance tables in this manual.
Where the return duct system is not complete, the return con-
nection must run full size to a location outside the utility room
or basement. For further details, consult Section 5.3 (Air for
Combustion and Ventilation) of the National Fuel Gas Code,
ANSI Z223.1, or CAN/CGA B149.1 or .2, Installation Code
latest editions.
Bottom Return
Bottom return applications normally pull return air through a
base platform or return air plenum. Be sure the return plat-
form structure is suitable to support the weight of the furnace.
Refer to Figure 1 on page 7 for unit dimensions and Table 3
on page 7 for unit weights. Be sure to seal the furnace to ple-
num connection to prevent air leakage.
The bottom panel is equipped with a perforated opening for
easy removal. Tabs must be cut with sheet metal snips to
allow removing knockout. Scribe marks are included for form-
ing flanges for attachment of the return air ductwork.
NOTE:
If an external mounted filter rack is being used, see
the instructions provided with that accessory for proper hole
cut size.
Upflow attic installations must meet all minimum clearances
to combustibles and have floor support with required service
accessibility.
APPLICATION
HORIZONTAL
NOTE:
If an external mounted filter rack is being used, see
the instructions provided with that accessory for proper hole
cut size.
FIGURE 3 :
Side Filter Retainer Placement
FIGURE 4 :
Side Return Cutout Markings
FILTER
PROVIDED
POSITION WIRE RETAINER
PROVIDED UNDER FLANGE
CLIPS
RIGHT SIDE
INSTALLATION
SHOWN
FURNACE
FRONT
CORNER
MARKINGS
FRONT OF
FURNACE
All installations must have a filter installed.
