McQuay IM 672-3
17
Operation Guidelines
8
Leak test the thermal system to verify that connections are
tight.
9
Check that the condensate drain is trapped.
10
Rotate the shaft by hand to be sure it is free.
Fan startup:
Start and run fan. Observe the rotation. If the fan operates
backward, reverse two legs of the three-phase supply power.
Note –
Variable pitch fan drives usually are provided for operation
in the mid-speed adjustment range. However, the drives
usually ship with the adjustment opened up for minimum
fan speed. Adjust the drives for the proper airflow. See
“Fan Drive Adjustments” on page 21.
After the first 48 hours of operation:
1
Disconnect and lock electrical power source.
2
Check tightness of all bearing, wheel, and sheave setscrews
(or capscrews). See Table 6.
3
Recheck belt tension and adjust if necessary. Belts
tensioned sufficiently to slip one to two seconds at startup
will perform satisfactorily, extending life and reducing
vibration. If retensioning is necessary, be certain to retain
sheave alignment.
Fan Wheel Alignment
Figure 27: Wheel-to-inlet funnel relationship—airfoil
typefan wheels (housed)
Notes:
1. To obtain rated air performance, dimensional relationship must be held.
2. To obtain dimension A, loosen setscrews in wheel hub(s), shifting wheel(s)
axially as needed, retightening setscrews.
3. To obtain dimension B, loosen screw and washer fasteners around
periphery of funnel(s), shifting funnel radially as required, re-torquing
fasteners.
Figure 28: Wheel-to-inlet funnel relationship—forward
curved type fan wheels
Notes:
1.To obtain rated air performance, dimensional relationship must be held.
2. Adjust dimension C by loosening wheel hub setscrews, shifting wheel(s)
axially as needed, and retightening setscrews.
Figure 29: Wheel-to-inlet funnel relationship—plenum fans
Table 2: Wheel-to-inlet funnel relationship—airfoil type
Airfoil
Unit sizes 003 to 035
Unit sizes 040 to 090
Dia.
A
(in)
A
(mm)
B
(in)
B
(mm)
Dia.
A
(in)
A
(mm)
A
(in)
B
(mm)
13.22 4.56
116
0.21
5.33 20.00 7.19
183
0.31
7.87
14.56 5.06
129
0.21
5.33 22.25 7.69
195
0.33
8.38
16.18 5.62
143
0.21
5.33 24.50 8.56
217
0.31
7.87
17.69 6.90
175
0.22
5.59 27.00 9.47
241
0.63 16.00
21.56 7.59
193
0.24
6.10 30.00 10.47
266
0.39
9.91
24.00 8.45
215
0.23
5.84 33.00 11.75
298
0.38
9.65
36.50 12.78
325
0.38
9.65
40.25 14.31
363
0.50 12.70
A
A
B
E q u a l s p a c i n g
a l l a r o u n d
Table 3: Wheel-to-inlet funnel relationship—forward curved
type fan wheels
Forward curved
Unit sizes 003 to 035
Unit sizes 040 to 090
Diameter (in)
C
(in)
C
(mm)
Diameter (in)
C
(in)
C
(mm)
9 x 4
0.25
6.35
20 (Class 1 & 2)
0.24
6.10
9 x 7
0.13
3.30 22.38 (Class 1 & 2) 0.41
10.41
9 x 9
0.25
6.35
25 (Class 1 & 2)
0.47
11.94
10
0.22
5.59 27.62 (Class 1 & 2) 0.47
11.94
12
0.35
8.89
30 (Class 1 & 2)
0.47
11.94
15
0.44
11.18
33 (Class 1 & 2)
0.50
12.70
18
0.25
6.35
36 (Class 1 & 2)
0.75
19.05
20 (Class 1 & 2)
0.73
8.54
22 1/2 (Class 1 & 2) 0.59
14.99
24 1/2 (Class 1 & 2) 0.56
14.22
Table 4: Wheel-to-inlet funnel relationship—plenum fans
Wheel—funnel overlap
Size
Overlap
13.5
.120
15
.190
16.5
.250
18.25
.310
20
.380
22.25
.440
24.5
.500
27
.560
30
.620
33
.750
36.5
.810
40.25
.880
44.5
.940
49
1.000
54.25
1.060
60
1.120
I n l e t
F u n n e l
W
h e e l
C
C
I n l e t
F u n n e l
Overlap
