58
RT-SVX063G-EN
Direct-Drive Supply Fan Speed
Adjustment
Units equipped with a DDP Supply Fan do not use belt/
sheave arrangements to adjust fan speed.
This adjustment (if required) is made through the Fan VFD
by setting the supply fan Min/Max frequency at each supply
fan VFD using
Table 24.
RPM and Hz ranges for DDP supply fan
speed adjustments
Fan Speed (RPM)
VFD Frequency Range (Hz)
Max
Min
Max
Min
2400
888
83
31
2300
851
79
29
2200
814
76
28
2100
777
72
27
2000
740
69
26
1900
703
66
24
1800
666
62
23
1700
629
59
22
1600
592
83
31
1500
555
79
29
1400
518
74
27
1300
481
68
25
Table 24.
RPM and Hz ranges for DDP supply fan
speed adjustments (continued)
Fan Speed (RPM)
VFD Frequency Range (Hz)
Max
Min
Max
Min
1200
444
63
23
1100
407
58
21
1000
370
53
20
Note:
Maximum operating speed cannot exceed fan wheel
mechanical limit.
System Airflow Measurements
VAV and CV Systems with DDP Supply
Fan and Motorized Impeller Relief Fan
(optional)
Supply and Relief Airflow Measurement
Piezometer pressure taps are available to measure supply
and relief airflow. Piezometer pressure taps can interface
with customer-supplied airflow monitoring systems using
the F or K-factors and equation shown in the tables below.
Attach one end of the pressure differential gauge to a
connection in the fan cone throat, and the second to the fan
inlet plate to read pressure immediately upstream of the
fan.
Table 25.
Piezo airflow calculation
Unit
Fan dia,
in
F
C1
A
20,25,30
16.5
1518.6
753.06
0.55
40,50,55
18.2
1821.9
692.03
0.72
20,25,30,40-
,50,55
20
2185.8
692.03
0.87
20,25,30,60-
,70,75
22.2
2713.9
692.03
1.07
40,50,55
24.5
3285
692.03
1.3
60,70,75
27
3397.6
692.03
1.58
Notes:
1
.
Measure pressure from inlet side of fan to piezo tap at
the cone throat.
2
.
Fan inlet will be the high pressure side.
3
.
dP can be up to 25 in h
2
0.
4
.
Coefficients are for one fan. For two fans double result
or F and C1 values.
5
.
For standard density of 0.075 lb/ft^3, Supply Fan CFM =
CFM = F * √ dP
6
.
For non-standard density, Supply Fan CFM = CFM = C1
* A * √ (dP / ρ), where dP is the piezo pressure
differential and rho is the actual air density.
For relief fans, check the nameplate model number on the
fan to determine the K-factor, see table below.
Содержание IntelliPak with Symbio 800
Страница 16: ...16 RT SVX063G EN Figure 1 20 to 30 ton front view inches 40 28 90 63 27 31 FRONT VIEW 20 30T Dimensional Data ...
Страница 18: ...18 RT SVX063G EN Figure 3 40 to 55 ton front view inches 27 31 40 28 90 63 FRONT VIEW 40 55T Dimensional Data ...
Страница 64: ...64 RT SVX063G EN Figure 37 Dry bulb changeover map Startup the Unit ...
Страница 137: ...RT SVX063G EN 137 Notes ...
Страница 138: ...138 RT SVX063G EN Notes ...
Страница 139: ...RT SVX063G EN 139 Notes ...