Table of Contents
Advertisement
Figure 5B – Adjustable Motor Base
VC2-319-1774
FAN BELT ADJUSTMENT
Some of the smaller axial fan models use individual V-
belts, but most of the models use multi-groove, banded
belts. Belt tension should be checked and adjusted
(as needed) every month. To properly adjust the belt
tension, position the fan motor so that moderate pressure
on the belt midway between the sheaves will produce 1/2"
deflection in centrifugal fan units and the deflection shown
in Table 4 below for axial fan units. The position of the fan
motor can easily be changed by adjusting the rod which
extends from the frame to the motor base.
1. Loosen the locking nut (See Figure 5, 5a, 5b)
2. Rotate the adjusting nut
a. To loosen belt tension, turn clockwise (on models
VTL, VFL and VCL turn counterclockwise).
b. To tighten belt tension, turn counterclockwise (on
models VTL, VFL and VCL turn clockwise).
3
Tighten the locking nut – failure to do so may result in
the motor base vibrating free, hence, loosening the
belt tension.
Note: There should be no "chirp" or "squeal" when the fan
motor is started.
TABLE 4. Fan Belt Deflection for VC2 Models
MODEL NO.
VC2-N138-N191
VC2-N206-N235
VC2-N261-N301
VC2-N356-N446
VC2-319-1774
ADJUSTING
SCREW
HINGE
DEFLECTION
(inches)
9/16 "
11/16 "
11/16 "
13/16 "
13/16 "
FAN DRIVES
The drive alignment should be checked annually to
ensure maximum belt life. This can be done by placing
a straightedge across both sheaves as shown in Figure 6.
When the drive is properly aligned, the straightedge will
contact all four points as indicated. If realignment is nec-
essary, loosen the motor sheave and align it with the fan
sheave. Allow approximately 1/4" for draw-up as the
motor sheave is pulled tight on the bushing, then retighten
the bushing screw:
MOTOR
SHEAVE
POINT OF CONTACT
Figure 6 – Checking Sheave Alignment
MOTOR REPLACEMENT
On rare occasions, the fan motor will have to be replaced.
On the VC2 models, make sure the drain holes are point-
ing in the downward direction. This may require that the
end bell be reversed on some motors.
SPRAY NOZZLES AND HEAT TRANSFER SECTION
The spray nozzles and heat transfer section should
be inspected and cleaned each month. The inspection
procedure is as follows:
1. Shut off the fan, but leave the pump running.
2. Remove the eliminators.
3. Check to see if the nozzles are producing the spray
pattern shown in Figure 7a for cooling towers or 7b for
coil products.
4. Clean any nozzles which are clogged. If necessary,
the nozzle and rubber grommet may be removed for
cleaning.
5. Inspect the coil or wet deck surface. Any corrosion,
damage, or obstructions must be corrected.
6. Some VF1, VFL, VC1, VC2, and VCL units are provid-
ed with an extended surface finned coil. During the win-
ter season, when the ambient temperature is well
below design, units with this coil can operate with the
spray pump off. The coil is designed for seasonal dry
operation followed by seasonal wet operation, and not
for frequent cycling of the spray pump. Frequent spray
pump cycling may lead to excessive scale buildup.
Caution: Do not use steam or high pressure water to
clean cooling tower wet deck surface of materials
other than steel.
FAN
SHEAVE
STRAIGHTEDGE
11
Advertisement
Table of Contents
