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Filters—Read This Section Before Installing the Return Air Ductwork
Filters must be used with this furnace. Discuss filter
maintenance with the building owner.
Filters do not ship with this furnace, but must be provided,
sized and installed externally by the installer.
Filters must comply with UL900 or CAN/ULCS111 standards.
If the furnace is installed without filters, the warranty will be
voided.
Minimum Filter Requirements Chart
Upflow—Cooling Airflow Requirement (CFM)—Permanent Minimum Filter Area (sq. in.) Based On 600 ft
(182.9 m) Per Minute Filter Face Velocity
Input Airflow
600
0453_XA
376*
0704_XA
-
0905_XA
-
1155_XA
-
Counterflow—Cooling Airflow Requirement (CFM)—Permanent Minimum Filter Area (sq. in.) Based On
600 ft (182.9 m) Per Minute Filter Face Velocity
0704_XA
-
0905_XA
-
Upflow—Cooling Airflow Requirement (CFM)—Permanent Minimum Filter Area (sq. in.) Based On 300 ft
(91.4 m) Per Minute Filter Face Velocity
0453_XA
376*
0704_XA
-
0905_XA
-
1155_XA
-
Counterflow—Cooling Airflow Requirement (CFM)—Permanent Minimum Filter Area (sq. in.) Based On
300 ft (91.4 m) Per Minute Filter Face Velocity
0704_XA
-
0905_XA
-
*Minimum filter area dictated by heating airflow requirement.
32
800
1,000
384
480
-
627*
-
-
-
-
-
320*
-
-
384
480
-
564*
-
-
-
-
-
641*
-
-
On upflow units, guide dimples locate the side return cutout
locations. Use a straight edge to scribe lines connecting the
dimples. Cut out the opening on these lines.
NOTE: An undersized opening will cause reduced airflow.
Refer to Minimum Filter Requirement charts to determine filter
area requirements.
1,200
1,400
576
-
627*
672
836*
836*
940*
940*
320*
336
427*
427*
576
-
564*
672
752*
752*
940*
940*
641*
672
854*
854*
1,600
2,000
-
-
768
-
836*
960
940*
960
384
-
427*
480
-
-
768
-
768
960
940*
960
768
-
854*
960
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