User’s Information Manual
9
441 02 2011 00
Replacement filters should be of the same type and size as the origi-
nal filters, to ensure adequate air flow and filtering. A disposable low
velocity filter can be replaced with a washable high velocity type. Do
not replace a high velocity filter with a disposable low velocity filter,
except as permitted below.
If a cleanable (high--velocity) filter(s) is to be replaced with a dispos-
able (low--velocity) filter(s), the airflow area of the filter(s) must be
doubled (i.e., a second filter of the same size must be installed so
that only half of the air goes through each filter). A second return--air
duct to the furnace may be required in which to install the second
filter. Modification of a furnace installation shall comply with the lo-
cal installation code and the furnace installation instructions, and
shall be made only by a Qualified Service Agency.
NOTE: Some filters are marked with an arrow to indicate the
proper direction of air flow through the filter. The air flow direc-
tion will be towards the blower motor. Make sure filter is
installed correctly.
Filter Replacement -- Upflow
The filter may be installed inside the bottom of the furnace blower
compartment, or the filter(s) rack may be installed under the furnace
or on either or both sides of the furnace. A plastic end cap(s) is in-
serted in the filter rack(s) after the filter(s) is installed. The end cap
keeps air from escaping around the open end of the filter rack. See
Figure 7
and
Figure 8
for side and bottom locations. Rack end cap
is similar for bottom mounted filter rack.
Filter rack(s) attached to the outside of the furnace is made so the
filter simply slides out one end for removal.
RISK OF REDUCED FURNACE LIFE
Use of excessively dirty and/or restrictive air
filters
may
increase
furnace
operating
temperatures and shorten the life of the furnace.
Filters specified for the furnace are rated at a
maximum of 600 FPM air velocity and sized for the
furnace’s airflow rate. Replacement filters must be of
equivalent type, size, and rating except as described
below.
Disposable, low--velocity filters may be used to replace
washable, high--velocity filters, providing they are sized
for 300 FPM or less.
If you are uncertain of the type of replacement filter to use,
consult the furnace installer or a qualified service agency
for assistance.
!
CAUTION
Filter Replacement -- Bottom or Side
Mounted Filter Rack Outside Furnace
1. Turn
OFF
electric power to furnace.
2. Remove the end cap from the filter rack.
3. Slide the filter out of the filter rack. See
Figure 7
.
4. Inspect the filter(s) and replace or clean washable types. If
filter is aluminum mesh it should be recoated with filter coat-
ing spray.
5. Reinstall the end cap in the filter rack.
6. Turn on electric power to furnace.
Filter Rack Outside Furnace
Figure 7
25--24--62--1
Filter Rack End cap
Filter Replacement -- Bottom Mounted Filter
Inside Furnace,
1. Turn off electric power to furnace.
2. Remove blower door.
3. Slide filter straight out toward you. See
Figure 8
.
4. Inspect the filter(s) and replace or clean washable types. If
filter is aluminum mesh it should be recoated with filter coat-
ing spray.
5. Replace blower door.
6. Turn on electric power to furnace.
Figure 8
Bottom Mounted Filter
Inside Furnace
25--24--18--1
9
²
Center Clip
side--to--side
Filter Replacement -- Horizontal and
Downflow *8MPN/L (Not *8DNL)
The filter may be installed at the inlet end of the blower compart-
ment, either inside or outside the furnace. Side inlet filter locations
are not permitted for horizontal or downflow applications.
Filter Replacement ---- Downflow *8DNL
Two filters are supplied with all *8DNL downflow models. (See to
Figure 9
) Refer to note for proper size. The filters are installed
through the top of the downflow furnace from the right side. To re-
move filter, refer to
Figure 9
for the following steps.
NOTE:
Two (2) 16
²
x 18
²
cleanable high--velocity filters are recom-
mended. A *8DNL downflow furnace with airflow up to 1200 cfm is
permitted to replace the 16
²
x 18
²
cleanable high--velocity filters
with two 16
²
x 18
²
disposable filters.
