IDC2 EVAPORATIVE CONDENSERS
MAINTENANCE
140.940-IOM (DEC 13)
Page 14
- When the belt is properly tensioned, align the adjustment
bolt to facilitate replacement of the locking wrench. Re-
place the locking wrench and tighten the plastic thumb-
screw to secure.Alignment
•
Check the drive alignment annually to ensure maximum belt life.
•
Drive alignment check and adjustment:
- Place a straight edge across the driver and the driven
sheaves as shown in
Figure 16
.
- The straight edge should contact all four points as shown
in
Figure 16
indicating that the drives are properly aligned.
- There should be no more than 1/16” deviation from four
points of contact.
- In case of realignment, loosen the motor sheave and
align it with the fan sheave. Allow 1/4” for draw-up as
the bushing screw is retightened.
WARNING
Check to ensure the controls for the fan motor are set to
allow a maximum of six on-off cycles per hour to prevent
motor overload.
Figure 16 - Drive Alignment
- The motor base assembly has been pre-aligned at the fac-
tory. Mount the motor base assembly to the unit and verify
alignment. Install the belt and follow the belt tensioning
directions below. [IDC2-x-7409-x and IDC2-x-7418-x]
•
Seasonal Start-Up
: Readjust the tension on the belt.
•
Operation
: After the first 24 hours of operation, readjust
the belt tension on a new unit start-up or installation of a
new belt. Thereafter, check the belt condition monthly, and
adjust tension as necessary. Readjust tension at least once
every three months.
•
Belt tension check:
- Place a straight edge along the belt from sheave to sheave
as shown in
Figure 14a
, or use a tape measure as shown
in
Figure 14b
to measure belt deflection.
- Apply a moderate force by hand (approximately
40 lb/275 kPa) evenly across the width of the belt in the
center of the span between the sheaves.
- There is adequate belt tension if the belt deflects between
1/4” and 3/8” as shown in
Figures 14a
and
14b
.
Driven Sheave
Driven Sheave
Belt
Driver Sheave
Straight Edge
1/4” to 3/8” Deflection = Proper Belt Tension
1/4” to 3/8” Deflection = Proper Belt Tension
Tape Measure
Belt
Driver Sheave
Figure 14a - Belt Tension with a Straight Edge
Driven Sheave
Driven Sheave
Belt
Driver Sheave
Straight Edge
1/4” to 3/8” Deflection = Proper Belt Tension
1/4” to 3/8” Deflection = Proper Belt Tension
Tape Measure
Belt
Driver Sheave
Figure 14b - Belt Tension with a Tape Measure
NOTICE
There should be no “chirp” or “squeal” when the fan mo-
tor is started.
Belt tension adjustment (if required):
- Remove the locking wrench (wrench attached to casing
near motor/door) by loosening the plastic thumbscrew.
- Using the supplied locking wrench, wrench or impact
gun, turn the motor base adjusting bolt (
Figures 15a
and
15b
) clockwise to tension the belt, or counterclockwise
to relieve belt tension. During adjustment of belt tension,
the drives should be rotated several times by hand to
evenly distribute the tension throughout the belt.
Motor
Adjusting
Bolt
Figure 15a - External Motor
Figure 15b - Internal Motor
Motor
Adjusting
Bolt