Table 28: Altitude/Temperature Correction Factors
Altitude (ft)
Air Temp.
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
Figure 28: 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
airflow performance data is 3,000 CFM, 1.4 IWC and
2.0 BHP?
Solution:
At an elevation of 5,000 ft, the
indoor blower will still deliver 3,000 CFM if the rpm
is unchanged. However, the Altitude correction
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. The Altitude/
Temperature Factors show the correction factor to
be 0.832. Corrected static pressure = 1.4 x 0.832 =
1.16 IWC Corrected BHP = 2.0 x 0.832 = 1.66
Example 2:
A system, located at 5,000 ft of elevation,
is to deliver 3,000 CFM at a static pressure of 1.4".
Use the unit 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 1.4" 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 = 1.4" / .832 = 1.68".
Enter the Supply Air Blower Performance Table at
3,000 CFM and static pressure of 1.68". The rpm
listed will be the same rpm needed at 5,000 ft.
Suppose that the corresponding BHP listed in
the table is 2.0. This value must be corrected for
elevation.
BHP at 5,000 ft. = 2.0 x .832 = 1.66
Drive Selection
1. Determine side or bottom supply duct
Application.
2. Determine desired airflow.
INSTALLATION MANUAL ZY SERIES 3 - 10 ton 60 Hertz R-410A
83
Johnson Controls Ducted Systems
Summary of Contents for ZY Series
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