Specifications

Filter Arrangement
FIRE, CARBON MONOXIDE AND POISONING
HAZARD
Failure to follow this warning could result in personal
injury, or death.
Never operate a furnace without a filter or filtration device
installed. Never operate a furnace with filter or filtration
device access doors removed.
Furnaces shipped without a filter rack:
There are no provisions for an internal filter in these furnaces.
An external filter rack is required and is purchased separately.
A field supplied accessory air cleaner may also be used in
place of the filter rack.
For upflow applications, the filter can be installed on either side
of the furnace, the bottom of the furnace or any combination of
side and bottom of the furnace. (See Figure 27, Figure 29, and
Figure 30)
For downftow applications, the filter rack (or field supplied
accessory air cleaner) must only be connected to the bottom
opening on the furnace (See Figure 26 and Figure 30 and
Table 7).
For horizontal applications, the filter rack (or field supplied
accessory air cleaner) can be connected to the bottom opening
on the furnace. For side return use in the horizontal position,
refer to Figure 28. If both side and bottom openings are used in
Figure 28, each opening used will require a filter.
A filter rack or any field supplied accessory air cleaner can also
be installed in the common return duct prior to entering the
return air opening in any orientation.
See Table 6 for recommended filter size details.
Table 6 Filter Size Information - inch (mm)
FILTERSIZE
FURNACE
CASING
WIDTH
SIDE RETURN
BOTTOM
RETURN
FILTER
TYPE
17--1/2 16 x 25 x 3/4 16 x 25 x 3/4 Washable*
(445) (406 x 635 x 19) (406 x 635 x 19)
16 x 25 x 3/4 20 x 25 x 3/4 Washable*
21 (533) (406 x 635 x 19) (508 x 635 x 19)
24-1/2 16 x 25 x 3/4 24 x 25 x 3/4 Washable*
(622) (406 x 635 x 19) (610 x 635 x 19)
Recommended to maintain air filter face velocity. See Product Data for part
number.
Refer to the instructions supplied with the Filter Rack or
accessory air filter for additional assembly and installation
options.
Downflow Return Air
Figure 26
Configurations and Restrictions
X
NOT PERMITTED
0
®
L10F033
Upflow Return Air Configurations
Figure 27 and Restrictions
® ®
® ®
O
®
RETURN
AIR
RETURN T _'1_ UPFLOW
AI R RETURN AIR
RESTRICTIONS
Lt0F032
Horizontal Return Air
Figure 28
Configurations and Restrictions
RETURN
AIR O
SUPPLY
AIR
i....................._' / .......
._;_;_ .........RETURN AIR
* NOTE: RESTRICTION SAME FOR AIR RESTRICTIONS
HORIZONAL LEFT
L10F034
440 01 4201 01 Specificati ..... bject to change without notice. 23