5167821-YTG-K-1118
74
Johnson Controls Ducted Systems
Drive selection
1.
Determine side or bottom supply duct application.
2.
Determine desired airflow.
3.
Calculate or measure the amount of external static pressure.
4.
With the operating point determined from steps 1, 2, and 3, locate this point on the appropriate supply air blower performance
table. Linear interpolation may be necessary.
5.
Note the RPM and BHP from step 4 and 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 the 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 and 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 achieves 1230 RPM.
Airflow performance
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 and drive
Alternate 2 HP & Drive
2200
804
0.50
866
0.71
925
0.90
982
1.06
1038
1.21
1092
1.35
1147
1.48
1203
1.61
1259
1.73
1317
1.87
2400
835
0.66
897
0.87
956
1.06
1013
1.22
1069
1.37
1124
1.51
1178
1.64
1234
1.77
1290
1.90
1348
2.03
2600
869
0.84
931
1.05
990
1.24
1047
1.40
1103
1.55
1158
1.69
1212
1.82
1268
1.95
1324
2.07
1382
2.21
2800
906
1.03
968
1.25
1027
1.43
1084
1.60
1139
1.75
1194
1.89
1249
2.02
1304
2.14
1361
2.27
-
-
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
X
Y
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-in. pleated filter
Electric heat kW
3
6
9
15
20
24
X
Y
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
