5
Operation and Maintenance Instructions
Fan System
The fan system must be checked regularly and lubricated at
the proper intervals. The following maintenance schedule is
recommended.
Fan Motor Bearings
The motors are built to “Cooling Tower Duty” specifications.
The fan motor bearings for motors up to 30 kW are lubricated
for the lifecycle of the bearings, higher motor powers require
relubrication (please see motor manual for more detail). After
extended shut-downs, the motor should be checked with an
insulation tester prior to be restarted.
Fan Shaft Ball Bearings
Lubricate the fan shaft bearings every 1,000 hours of operation
or every three months for induced draft units. Lubricate the
fan shaft bearings every 2,000 hours of operation or every
six months for forced draft units. Use any of the following
synthetic waterproof, inhibited greases which are suitable for
operation between -40°C and 120°C. (For colder operating
temperatures, contact the factory).
- Chevron - Multifak Premiums 3 - Total - Ceran WR2
- Shell Alvanias - or similar
Fan Shaft Sleeve Bearings
(1,2 m LS units only)
Lubricate the intermediate sleeve bearing(s) before unit start
up. The reservoir should be checked several times during
the first week to ensure that the oil reserve is brought to
full capacity. After the first week of operation, lubricate the
bearing(s) every 1.000 hours of operation or every three
months (whichever occurs first).
Use one of the following industrial grade, non-detergent mineral
oils. Do not use a detergent based oil or oils designated
heavy duty or compounded. Different oils may be required
when operating at temperatures below 0°C continuously.
Table 1 provides a short list of approved lubricants for each
temperature range.
Ambient Temp Texaco Mobil Exxon Total
-32°C to 0°C - DTE Heavy - -
-17°C to 43°C - - - -
0 to 38°C Regal R&O 220 DTE Oil BB Teresstic 220 -
All bearings used on EVAPCO equipment are factory adjusted
and self aligning. Do not disturb bearing alignment by
tightening the sleeve bearing caps.
Fan Belt Adjustment
The fan belt tension should be checked at start up and again
after the first 24 hours of operation to correct for any initial
stretch. To properly adjust the belt tension, position the fan
motor so that the fan belt will deflect approximately 10 mm
when moderate pressure is applied midway between the
sheaves. A properly tensioned belt will not “chirp” or “squeal”
when the fan motor is started.
Air Inlet
Inspect the air inlet louvers (induced draft units) or fan screens
(forced draft units) monthly to remove any paper, leaves or
other debris that may be blocking airflow into the unit.
Fan System - Capacity Control
There are several methods for capacity control of the
evaporative cooling unit.
Note: for the eco-ATW with Sage
2
and eco-ATWE with Sage
3
consult the manual.
1. Fan Motor Cycling
Fan Motor Cycling requires the use of a single stage
thermostat which senses the fluid temperature (closed
circuit coolers) or condensing temperature (evaporative
condensers). The contacts of the thermostat are wired in
series with the fan motor’s starter holding coil.
In this method, there are only two stable levels of
performance: 100% of capacity when the fan is on,
and approximately 10% of capacity when the fan is off.
Controls should be set to only allow a maximum of six
start/stop cycles per hour.
IMPORTANT:
THE RECIRCULATION PUMP MAY NOT BE USED AS A
MEANS OF CAPACTY CONTROL AND SHOULD NOT BE
CYCLED MORE THEN SIX START/STOP CYCLES PER HOUR.
2. Two Speed Motors
The use of a two-speed motor provides an additional step
of capacity control when used with the fan cycling method.
The low speed of the motor will provide approximately
60% of full speed capacity.
Two-speed capacity control systems require not only a two-
speed motor, but also a two-stage thermostat and the proper
two-speed motor starter.
It is important to note that when two-speed motors are to
be used, the motor starter controls must be equipped with
a decelerating time delay relay. The time delay should be a
minimum of a 30 second delay when switching from high
speed to low speed.
3. Variable Frequency Drives
The use of a variable frequency drive (VFD) provides the
most precise method of capacity control. By adjusting the
voltage and frequency, the AC induction motor can operate
at many different speeds.
VFD technology has particular benefit on evaporative
cooling units operating in cold climates where airflow can
be modulated to minimize icing and reversed at low speed
for de-icing cycles.
The VFDs need to have a pre-set shutoff to prevent water
temperatures from becoming too cold and to prevent
the drive from trying to turn the fan at near zero speed.
Operating below 25% of motor speed achieves very little
return in fan energy savings and capacity control. Check
with your VFD supplier if operating below 25% is possible.
NOTE: Pump Motors: VFD’s should not be used on pump
motors. The pumps are designed to be operated at
full speed and are not intended to be used as capacity
control.
Table 1 – Sleeve Bearing Lubricants
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