Altitude/Temperature Correction Factors; Belt Adjustment - Johnson Controls TempMaster ZD Series Installation Manual

Blower Rotation
Check for proper supply air blower rotation. If the blower is
rotating backwards, the line voltage at the unit point of power
connection is misphased (See 'PHASING').
Belt Tension
The tension on the belt should be adjusted as shown in Figure 20.
(A)
Figure 19: Belt Adjustment
Table 14: 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
Johnson Controls Ducted Systems
Defl Force
(B)
*Never Loosen
(C)*
2000 3000
0.986 0.950
0.966 0.931
0.948 0.913
0.930 0.896
0.913 0.880
0.897 0.864
0.880 0.848
Procedure for adjusting belt tension:
1. Loosen six nuts (top and bottom) A.
2. Adjust by turning (B).
3. Never loosen nuts (C).
4. Use belt tension checker to apply a perpendicular
force to one belt at the midpoint of the span as shown.
Deflection distance of 4mm (5/32") is obtained.
To determine the deflection distance from normal position,
use a straight edge from sheave to sheave as reference
line. The recommended deflection force is as follows:
Tension new belts at the max. deflection force
recommended for the belt section. Check the belt
tension at least two times during the first 24 hours of
operation. Any retensioning should fall between the min.
and max. deflection force values.
5. After adjusting re-tighten nuts (A).
CFM Static Pressure and Power-Altitude and Temperature
Corrections
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
in Table 14 and Figure 20.
Altitude (Ft.)
4000 5000 6000
0.916 0.882 0.849
0.898 0.864 0.832
0.880 0.848 0.816
0.864 0.832 0.801
0.848 0.817 0.787
0.833 0.802 0.772
0.817 0.787 0.758
5742640-TIM-A-0419
7000 8000 9000
0.818 0.788 0.758
0.802 0.772 0.743
0.787 0.757 0.729
0.772 0.743 0.715
0.758 0.730 0.702
0.744 0.716 0.689
0.730 0.703 0.676
10000
0.729
0.715
0.701
0.688
0.676
0.663
0.651
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