036-21584-002 Rev. A (1205)
Unitary Products Group
5
FILTER PERFORMANCE
The airflow capacity data published in the “Blower Perfor-
mance” table listed above represents blower performance
WITHOUT filters. To determine the approximate blower per-
formance of the system, apply the filter drop value for the fil-
ter being used or select an appropriate value from the “Filter
Performance” table shown below.
NOTE: The filter pressure drop values in the “Filter Perfor-
mance” table shown below are typical values for the type of
filter listed and should only be used as a guideline. Actual
pressure drop ratings for each filter type vary between filter
manufacturer.
APPLYING FILTER PRESSURE DROP TO
DETERMINE SYSTEM AIRFLOW
To determine the approximate airflow of the unit with a filter in
place, follow the steps below:
1.
Select the filter type.
2.
Select the number of return air openings or calculate the
return opening size in square inches to determine the
proper filter pressure drop.
3.
Determine the External System Static Pressure (ESP)
without the filter.
4.
Select a filter pressure drop from the table based upon
the number of return air openings or return air opening
size and add to the ESP from Step 3 to determine the
total system static.
5.
If total system static matches a ESP value in the airflow
table (i.e. 0.20, 0.60, etc,) the system airflow corre-
sponds to the intersection of the ESP column and Model/
Blower Speed row.
FILTER SIZES
Input / Output
BTU/H
CFM
Cabinet
Size
Side Return
Filter in.
Bottom Return
Filter in.
40/38
1200
A
16 x 25
14 x 25
60/56
1200
B
16 x 25
16 x 25
80/75
1200
B
16 x 25
16 x 25
80/75
1600
C
16 x 25
20 x 25
100/93
2000
C
16 x 25
20 x 25
120/112
2000
D
(2) 16 x 25
22 x 25
FILTER PERFORMANCE - PRESSURE DROP INCHES W.C. AND (KPA)
Airflow Range
Minimum Opening Size
Filter Type
Disposable
Washable Fiber
Pleated
1 Opening
2 Openings
1 Opening
2 Opening
1 Opening
2 Opening
1 Opening
2 Opening
Sq. in.
Sq. in.
In w.c.
In w.c.
In w.c.
In w.c.
In w.c.
In w.c.
0 - 750
230
0.01
0.01
0.15
751 - 1000
330
0.04
0.03
0.20
1001 - 1250
330
0.08
0.07
0.20
1251 - 1500
330
0.08
0.07
0.25
1501 - 1750
380
658
0.14
0.08
0.13
0.06
0.30
0.17
1751 - 2000
380
658
0.17
0.09
0.15
0.07
0.30
0.17
2001 & Above
463
658
0.17
0.09
0.15
0.07
0.30
0.17
UNIT CLEARANCES TO COMBUSTIBLES
Application
Top
Front
Rear
Left Side
Right Side
Flue
Floor/
Bottom
Closet
Alcove
Attic
In.
In.
In.
In.
In.
In.
Upflow
1
3
0
0
0
0
Combustible
Yes
Yes
