Altitude/Temperature Correction Factors - York ZV-06 Installation Manual

Table 18: Altitude/temperature correction factors
Air temp.
0 1000
40 1.060 1.022
50 1.039 1.002
60 1.019 0.982
70 1.000 0.964
80 0.982 0.947
90 0.964 0.929
100 0.946 0.912
1.100
1.050
1.000
0.950
0.900
0.850
0.800
0.750
0.700
0.650
0.600
Figure 27: Altitude/temperature correction factors
Use the examples below to assist in determining the airflow
performance of the product at altitude.
Example 1: What are the corrected CFM, static pressure, and
BHP at an elevation of 5,000 ft. if the blower performance data
is 1,400 CFM, 0.6 IWC and 0.67 BHP?
Solution: At an elevation of 5,000 ft. the indoor blower will still
deliver 1,400 CFM if the RPM is unchanged. However, you must
use Table 19 to determine the static pressure and BHP. We
assume an air temperature of 70°F because no temperature data
is given, Table 18 shows the correction factor to be 0.832.
Corrected static pressure = 0.6 x 0.832 = 0.499 IWC
Corrected BHP = 0.67 x 0.832 = 0.56
Example 2: A system, located at 5,000 feet of elevation, is to
deliver 1,400 CFM at a static pressure of 1.5 in. Use the unit
Johnson Controls Ducted Systems
2000 3000 4000
0.986 0.950 0.916
0.966 0.931 0.898
0.948 0.913 0.880
0.930 0.896 0.864
0.913 0.880 0.848
0.897 0.864 0.833
0.880 0.848 0.817
40 50 60
Air Temperature (ºF)
Altitude (ft.)
5000 6000 7000
0.882 0.849 0.818
0.864 0.832 0.802
0.848 0.816 0.787
0.832 0.801 0.772
0.817 0.787 0.758
0.802 0.772 0.744
0.787 0.758 0.730
70 80 90
blower tables to select the blower speed and the BHP
requirement.
Solution: As in the example above, no temperature
information is given so 70°F is assumed.
The 1.5 in. static pressure given is at an elevation of 5,000 ft.
The first step is to convert this static pressure to equivalent sea
level conditions.
Sea level static pressure = 0.6 / .832 = 0.72 in.
Enter the blower table at 1,400 sCFM and static pressure of
0.72 in. The RPM listed is the same RPM needed at 5,000 ft.
Suppose that the corresponding BHP listed in the table is 0.7.
This value must be corrected for elevation.
BHP at 5,000 ft. = 0.7 x .832 = 0.58
5567611-BIM-B-1218
8000 9000 10000
0.788 0.758 0.729
0.772 0.743 0.715
0.757 0.729 0.701
0.743 0.715 0.688
0.730 0.702 0.676
0.716 0.689 0.663
0.703 0.676 0.651
Sea Level
1000 ft
2000 ft
3000 ft
4000 ft
5000 ft
6000 ft
7000 ft
8000 ft
9000 ft
10000 ft
100
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