035-19624-001 Rev. A (0104)
24
Unitary Products Group
FILTER PERFORMANCE
The airflow capacity data published in Table 16 represents blower per-
formance WITHOUT filters. To determine the approximate blower per-
formance of the system, apply the filter drop value for the filter being
used or select an appropriate value from the Table 17.
NOTE:
The filter pressure drop values in Table 17 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 fil-
ter manufacturers.
* Hogs Hair Filters are the type supplied with furnace (if supplied).
APPLYING FILTER PRESSURE DROP TO
DETERMINE SYSTEM AIRFLOW
To determine the approximate airflow of the unit with a filter in place, fol-
low 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 pres-
sure 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 w.c. (50 Pa), 0.60 w.c. (150 Pa), etc,) the system airflow cor-
responds to the intersection of the ESP column and Model/Blower
Speed row.
6.
If the total system static falls between ESP values in the table (i.e.
0.58 w.c. (144 Pa), 0.75 w.c. (187 Pa), etc.), the static pressure
may be rounded to the nearest value in the table determining the
airflow using Step 5 or calculate the airflow by using the following
example.
Example: For a 130,000 BTUH (38.06 kW) furnace with 2 return open-
ings and operating on high-speed blower, it is found that total system
static is 0.58” w.c. To determine the system airflow, complete the follow-
ing steps:
Obtain the airflow values at 0.50 w.c. (125 Pa) & 0.60 w.c. (150 Pa)
ESP.
Airflow @ 0.50”: 2125 CFM (60.17 m
3
/min)
Airflow @ 0.60”: 2035 CFM (57.62 m
3
/min)
Subtract the airflow @ 0.50 w.c. (125 Pa) from the airflow @ 0.60 w.c.
(150 Pa) to obtain airflow difference.
2035 - 2125 = -90 CFM (2.55 m
3
/min)
Subtract the total system static from 0.50 w.c. (125 Pa) and divide this
difference by the difference in ESP values in the table, 0.60 w.c.
(150 Pa) - 0.50 w.c. (125 Pa), to obtain a percentage.
(0.58 - 0.50) / (0.60 - 0.50) = 0.8
Multiply percentage by airflow difference to obtain airflow reduction.
(0.8) X (-90) = -72
Subtract airflow reduction value to airflow @ 0.50 w.c. (125 Pa) to
obtain actual airflow @ 0.58 inwc (144 Pa) ESP.
2125 - 72 = 2053
Field Installed Accessories - Non-Electrical
TABLE 17:
Filter Performance - Pressure Drop Inches W.C. and (kPa)
AIRFLOW
RANGE
MINIMUM OPENING SIZE
FILTER TYPE
DISPOSABLE
HOGS HAIR*
PLEATED
1 Opening
2 Openings
1 Opening
2 Opening
1 Opening
2 Opening
1 Opening
2 Opening
Sq. in.
m
2
Sq. in.
m
2
In w.c.
Pa
In w.c.
Pa
In w.c.
Pa
In w.c.
Pa
In w.c.
Pa
In w.c.
Pa
0 - 750
230
.15
0.01
2.5
0.01
2.5
0.15
37
751 - 1000
330
.21
0.04
10
0.03
7.5
0.20
50
1001 - 1250
330
.21
0.08
20
0.07
17
0.20
50
1251 - 1500
330
.21
0.08
20
0.07
17
0.25
62
1501 - 1750
380
.25
658
.42
0.14
35
0.08
20
0.13
32
0.06
15
0.30
75
0.17
42
1751 - 2000
380
.25
658
.42
0.17
42
0.09
22
0.15
37
0.07
17
0.30
75
0.17
42
2001 & Above
463
.30
658
.42
0.17
42
0.09
22
0.15
37
0.07
17
0.30
75
0.17
42
Model No.
Description Use With
1NP0347
Propane (LP) Conversion
Kit all Models Except 140 MBH
1NP0349
LP Conversion Kit for 140 MBH Models
1CT0302
Concentric Intake/Vent 2” Pipe
1CT0303
Concentric Intake/Vent 3” Pipe
1PS0306
High Altitude Pressure Switch Kit (Does not include
orifices). For Application See 035-14447-000
1PS0307
High Altitude Pressure Switch Kit (Does not include
orifices). For Application See 035-14447-000
1PS0308
High Altitude Pressure Switch Kit (Does not include
orifices). For Application See 035-14447-000
1PS0309
High Altitude Pressure Switch Kit (Does not include
orifices). For Application See 035-14447-000
1PS0310
High Altitude Pressure Switch Kit (Does not include
orifices). For Application See 035-14447-000
1BR0314
EXTERNAL BOTTOM FILTER
RACK 14-1/2” CABINETS
1BR0317
EXTERNAL BOTTOM FILTER
RACK 17-1/2” CABINETS
1BR0321
EXTERNAL BOTTOM FILTER
RACK 21” CABINETS
1BR0324
EXTERNAL BOTTOM FILTER
RACK 24-1/2” CABINETS
1SR0302
External Side Filter Rack (6 pack)
1NK0301
CONDENSATE NEUTRALIZER KIT ALL MODELS
1PK0601
GAS & PRESSURE TEST KIT (without manometer)
1PK0602
GAS & PRESSURE TEST KIT (with manometer)
