Forced Draft Units; Troubleshooting - EVAPCO ATC-E Operation And Maintenance Instruction Manual

Operation and Maintenance Instructions

Forced Draft Units

Defrost cycles are NOT recommended for forced draft units, since allowing the leaving water temperature set point to rise
causes the fans to be off for very long periods of time . This is not recommended for forced draft coolers or condensers
because of the potential for freezing the fan drive components . Therefore, the defrost cycle is an inappropriate method of
ice management for forced draft units . However, low speed fan operation or variable frequency drives maintain a positive
pressure in the unit which helps prevent ice formation on the fan drive components .
For more information on cold weather operation, please request a copy of EVAPCO's Engineering Bulletin 23 .

Troubleshooting

Problem
Overamping Fan
Motors
Unusual Motor Noise
Incomplete Spray
Pattern
Possible Cause
Reduction in air static
pressure
Electrical issue
Fan rotation
Mechanical failure
Belt tension
Motor running single-
phase
Motor leads connected
incorrectly
Bad bearings
Electrical unbalance
Air gap not uniform
Rotor unbalance
Cooling fan hitting end
bell guard
Nozzles clogged
Pump running
backwards
Inadequate pump flow
for remote sump
Strainer clogged
Remedy
1 . On a forced draft unit verify that the pump is on, and water is
flowing over the coil . If the pump is off, and the unit was not sized
for dry operation, the motor may over-amp .
2 . If the forced draft unit is ducted, verify that the design ESP
matches the actual ESP .
3 . Verify the correct pump rotation direction . If the pump is rotating
incorrectly, it will result in less water flow, and therefore less
overall static pressure .
4 . Check the basin water level against the recommended level .
Note: Air density directly affects AMP reading .
1 . Check voltage across all three legs of the motor .
2 . Verify that the motor is wired per the wiring diagram, and
connections are tight .
Verify that the fan is rotating in the correct direction . If not, switch the
leads so it runs correctly .
Verify that the fan and motor turn freely by hand . If not, there may be
damage to the internal motor components or bearings .
Check for proper belt tension . Extreme belt tension can cause the
motor to overamp .
Stop motor and attempt to start it . Motor will not start again if single
phased . Check wiring, controls and motor .
Check motor connections against wiring diagram on motor .
Check lubrication . Replace bad bearings .
Check voltage and current of all three lines . Correct if required .
Check and correct bracket fits or bearing .
Rebalance .
Reinstall or replace fan .
Remove nozzles and clean . Flush water distribution system .
Visually verify pump rotor rotation by turning pump off and then on .
Verify amp draw .
Confirm inlet pressure at header meets recommended valves .
Adjust cylinder to provide blade tip clearance .
Remove strainer and clean
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