24
TIPS FROM CONTRACTORS:
Install a media cabinet capable
of incorporating a 4
−
in. (102 mm) thick media filter. This allows
room for future upgrades to other IAQ devices.
Design the duct system FIRST to determine how much
pressure drop may be allowed in the filter system. See the Air
Ducts section. Excessive filter pressure drop often
compromises system airflow and duct performance, causes
inadequate airflow to the furthest ends of the duct system, as
well as causes excess noise and higher than anticipated
electrical consumption.
NOTICE
Provide duct transitions, as required, to smoothly transition airflow
from the return duct system to the filter (or IAQ device) to the
furnace when the dimensions of the ductwork or furnace return air
opening do not match the required filter or IAQ device dimensions.
See the instructions supplied with factory
−
accessory duct adapters.
Table 5 – Filter Media Pressure Drop (Clean) Versus Airflow
−
In. W.C. (Pa)
14 x 25 Filter
(356 x 635 mm)
FactoryAccessory
Washable
FactoryAccessory
Media*
Representative AfterMarket Filter Media*
Fiberglass*
Pleated*
CFM
L/s
(1in. / 2.5 cm)
(4in. / 10 cm)
(1in. / 2.5 cm)
(2in. / 5 cm)
(1in. / 2.5 cm)
(2in. / 5 cm)
600
(283)
0.04
(12)
0.05
(12)
0.07
(17)
0.10
(26)
0.24
(60)
0.16
(40)
800
(378)
0.06
(15)
0.07
(19)
0.10
(25)
0.15
(39)
0.34
(85)
0.23
(59)
1000
(472)
0.07
(18)
0.10
(27)
0.13
(34)
0.21
(52)
0.32
(81)
1200
(566)
0.08
(20)
0.14
(36)
0.17
(43)
0.27
(68)
16 x 25 Filter
(406 x 635 mm)
FactoryAccessory
Washable
FactoryAccessory
Media*
Representative AfterMarket Filter Media*
Fiberglass*
Pleated*
CFM
L/s
(1in. / 2.5 cm)
(4in. / 10 cm)
(1in. / 2.5 cm)
(2in. / 5 cm)
(1in. / 2.5 cm)
(2in. / 5 cm)
600
(283)
0.04
(10)
0.05
(13)
0.06
(15)
0.09
(22)
0.20
(51)
0.13
(34)
800
(378)
0.05
(13)
0.07
(18)
0.08
(21)
0.13
(32)
0.29
(72)
0.20
(49)
1000
(472)
0.06
(16)
0.11
(28)
0.11
(28)
0.17
(43)
0.27
(67)
1200
(566)
0.07
(18)
0.15
(37)
0.14
(36)
0.22
(56)
1400
(661)
0.08
(21)
0.19
(48)
0.18
(45)
0.28
(70)
1600
(755)
0.09
(23)
0.24
(60)
0.21
(54)
1800
(850)
0.10
(25)
0.26
(64)
20 x 25 Filter
(508 x 635 mm)
FactoryAccessory
Washable
FactoryAccessory
Media*
Representative AfterMarket Filter Media*
Fiberglass*
Pleated*
CFM
(L/s)
(1in. / 2.5 cm)
(4in. / 10 cm)
(1in. / 2.5 cm)
(2in. / 5 cm)
(1in. / 2.5 cm)
(2in. / 5 cm)
800
(378)
0.04
(11)
0.05
(12)
0.06
(16)
0.09
(24)
0.22
(55)
0.15
(37)
1000
(472)
0.05
(13)
0.07
(18)
0.08
(21)
0.13
(32)
0.29
(72)
0.20
(49)
1200
(566)
0.06
(15)
0.09
(22)
0.11
(27)
0.16
(41)
0.25
(63)
1400
(661)
0.07
(17)
0.12
(31)
0.13
(33)
0.20
(51)
0.31
(79)
1600
(755)
0.08
(19)
0.15
(38)
0.16
(40)
0.24
(61)
1800
(850)
0.08
(21)
0.18
(47)
0.18
(47)
0.29
(73)
2000
(944)
0.09
(23)
0.22
(56)
0.21
(54)
2200
(1038)
0.09
(24)
0.26
(66)
0.25
(62)
25 x 25 Filter
(635 x 635 mm)
FactoryAccessory
Washable
FactoryAccessory
Media*
Representative AfterMarket Filter Media*
Fiberglass*
Pleated*
CFM
L/s
(1in. / 2.5 cm)
(4in. / 10 cm)
(1in. / 2.5 cm)
(2in. / 5 cm)
(1in. / 2.5 cm)
(2in. / 5 cm)
800
(378)
0.03
(9)
0.03
(8)
0.05
(12)
0.07
(18)
0.17
(43)
0.11
(28)
1000
(472)
0.04
(11)
0.05
(12)
0.06
(16)
0.09
(24)
0.22
(55)
0.15
(37)
1200
(566)
0.05
(13)
0.07
(17)
0.08
(20)
0.12
(31)
0.27
(68)
0.18
(47)
1400
(661)
0.06
(15)
0.09
(23)
0.10
(24)
0.15
(38)
0.23
(58)
1600
(755)
0.06
(16)
0.12
(31)
0.11
(29)
0.18
(45)
0.28
(69)
1800
(850)
0.07
(18)
0.14
(35)
0.13
(34)
0.21
(53)
2000
(944)
0.08
(19)
0.16
(41)
0.16
(39)
0.24
(61)
2200
(1038)
0.08
(21)
0.19
(49)
0.18
(45)
0.28
(70)
If the filter size that you are looking for is not contained in Table 5, refer to Table 6 for a comparison of Pressure Drop (initial/clean resistance
to airflow) versus Face Velocity for a variety of filter media types.
The following equations relate Face Velocity (FPM), Filter Area and Airflow (CFM):
Filter Face Velocity = Airflow / Filter Area
Minimum Filter Area = Rated System Airflow / Maximum Filter Face Velocity
912S
