User's Manual

1068152-YTG-L-0815
76 Johnson Controls Unitary Products
Altitude and Temperature Correction for CFM, Static
Pressure and Power.
The information below should be used to assist in application of
product when being applied at altitudes at or exceeding 1000
feet above sea level.
The air flow rates listed in the standard blower performance
tables are based on standard air at sea level. As the altitude or
temperature increases, the density of air decreases. In order to
use the indoor blower tables for high altitude applications,
certain corrections are necessary.
A centrifugal fan is a "constant volume" device. This means
that, if the RPM remains constant, the CFM delivered is the
same regardless of the density of the air. However, since the air
at high altitude is less dense, less static pressure will be
generated and less power will be required than a similar
application at sea level. Air density correction factors are shown
below.
Example Additional Static Resistance
Model
Size
(Tons)
CFM
Cooling
Only
Economizer 2” Filter
Electric Heat kW
6/6.5 10.5/11 14/15 16/16.5 24.8/27.8
ZX
08 (7.5),
09 (8.5),
12 (10.0),
14 (12.5)
2200 0.04 0.18 --- --- --- --- 0.07 0.09
2600 0.06 0.24 --- --- --- --- 0.09 0.11
3000 0.10 0.35 --- --- --- --- 0.12 0.14
3400 0.13 0.47 --- --- --- --- 0.15 0.18
3800 0.16 0.59 --- --- --- --- 0.19 0.22
4000 0.17 0.66 --- --- --- --- 0.21 0.24
4400 0.20 0.79 --- --- --- --- 0.25 0.29
4800 0.22 0.91 --- --- --- --- 0.30 0.34
5200 0.24 1.04 --- --- --- --- 0.35 0.39
5600 0.26 1.17 --- --- --- --- 0.41 0.45
6000 0.28 1.30 --- --- --- --- 0.48 0.52
Altitude/Temperature Correction Factors
Air
Temp.
Altitude (Ft.)
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
40 1.060 1.022 0.986 0.950 0.916 0.882 0.849 0.818 0.788 0.758 0.729
50 1.039 1.002 0.966 0.931 0.898 0.864 0.832 0.802 0.772 0.743 0.715
60 1.019 0.982 0.948 0.913 0.880 0.848 0.816 0.787 0.757 0.729 0.701
70 1.000 0.964 0.930 0.896 0.864 0.832 0.801 0.772 0.743 0.715 0.688
80 0.982 0.947 0.913 0.880 0.848 0.817 0.787 0.758 0.730 0.702 0.676
90 0.964 0.929 0.897 0.864 0.833 0.802 0.772 0.744 0.716 0.689 0.663
100 0.946 0.912 0.880 0.848 0.817 0.787 0.758 0.730 0.703 0.676 0.651
0.600
0.650
0.700
0.750
0.800
0.850
0.900
0.950
1.000
1.050
1.100
40 50 60 70 80 90 100
Air Temperature (ºF)
Correction Factor
Sea Level
1000 ft
2000 ft
3000 ft
4000 ft
6000 ft
7000 ft
8000 ft
9000 ft
10000 ft
5000 ft