5167540-YIM-H-0518
Johnson Controls Ducted Systems 39
Drive Selection
1. Determine side or bottom supply duct Application.
2. Determine desired airflow.
3. Calculate or measure the amount of external static pressure.
• Add or deduct any additional static resistance from “Additional Static Resistance Table”.
4. Using the operating point determined from steps 1, 2 & 3, locate this point on the appropriate supply air blower performance
table. (Linear interpolation may be necessary.)
5. Noting the RPM and BHP from step 4, locate the appropriate motor and, or drive.
6. Review the BHP compared to the motor options available. Select the appropriate motor and, or drive.
7. Review the RPM range for the motor options available. Select the appropriate drive if multiple drives are available for the
chosen motor.
8. Determine turns open to obtain the desired operation point.
Example
1. 2400 CFM
2. 1.6 IWC
3. Using the supply air blower performance table below, the following data point was located: 1230 RPM & 1.62 BHP.
4. Using the RPM selection table below, Size X and Model Y is found.
5. 1.62 BHP exceeds the maximum continuous BHP rating of the 1.5 HP motor. The 2 HP motor is required.
6. 1230 RPM is within the range of the 2 HP drives.
7. Using the 2 HP motor and drive, .5 turns open will achieve 1230 RPM.
Example Supply Air Blower Performance
Air Flow
(CFM)
Available External Static Pressure - IWG
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP
1.5 HP & Field Supplied Drive Standard 1.5 HP & Drive Hi Static 2 HP & Drive
2100 759 0.65 819 0.77 881 0.87 943 0.98 1005 1.08 1065 1.18 1121 1.28 1172 1.38 1217 1.48 1254 1.59
2200 778 0.73 838 0.84 900 1.95 962 1.05 1024 1.15 1083 1.25 1139 1.35 1191 1.45 1236 1.56 1273 1.66
2300 797 0.81 857 0.92 919 1.03 981 1.13 1043 1.23 1103 1.33 1159 1.43 1210 1.53 1255 1.64 1292 1.74
2400 817 1.90 877 1.01 939 1.12 1002 1.22 1063 1.32 1123 1.42 1179 1.52 1230 1.62 1275 1.73 1312 1.83
Example RPM Selection
Size
(Tons)
Model
Airflow
Option
HP
Max
BHP
Motor
Sheave
Blower
Sheave
6 Turns
Open
5 Turns
Open
4 Turns
Open
3 Turns
Open
2 Turns
Open
1 Turn
Open
Fully
Closed
XY
Std. 1.5 1.73 1VM50 AK74 N/A 897 945 991 1035 1079 1126
H. Static 2 2.30 1VM50 AK64 N/A 1039 1094 1150 1207 1256 1308
Example Additional Static Resistance
Size
(Tons)
Model CFM Cooling Only Economizer 4” Pleated Filter
Electric Heat kW
3 6 9 15 20 24
XY
900 0.05 -0.05 0.01 0.00 0.00 0.00 0.01 0.01 0.01
1000 0.05 -0.03 0.02 0.00 0.00 0.00 0.02 0.02 0.02
1100 0.04 -0.02 0.03 0.01 0.01 0.01 0.02 0.02 0.02
1200 0.04 0.00 0.04 0.01 0.01 0.01 0.02 0.02 0.02
1300 0.03 0.01 0.05 0.01 0.01 0.01 0.03 0.03 0.03
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