Altitude/Temperature Correction Factors - Coleman ZW Series Installation Manual

178113-BIM-D-0906
Table 13: 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
Figure 19: Altitude/Temperature Correction Factors
The examples below will 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 6,000 CFM, 1.5 IWC and 4.0 BHP?
Solution: At an elevation of 5,000 ft. the indoor blower will still
deliver 6,000 CFM if the rpm is unchanged. However, Table 13
must be used to determine the static pressure and BHP. Since
no temperature data is given, we will assume an air temperature
of 70°F. Table 14 shows the correction factor to be 0.832.
Corrected static pressure = 1.5 x 0.832 = 1.248 IWC
Corrected BHP = 4.0 x 0.832 = 3.328
Example 2: A system, located at 5,000 feet of elevation, is to
deliver 6,000 CFM at a static pressure of 1.5". Use the unit
Unitary Products Group
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
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
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" 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 = 1.5 / .832 = 1.80"
Enter the blower table at 6000 sCFM and static pressure of
1.8". The rpm listed will be the same rpm needed at 5,000 ft.
Suppose that the corresponding BHP listed in the table is 3.2.
This value must be corrected for elevation.
BHP at 5,000 ft. = 3.2 x .832 = 2.66
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
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