Below is a clear, practical guide for replacing a cooling-tower fan motor — what to check, how to remove the old unit, and how to install/align the new one. I’ll keep it very field-friendly.
✔️ Cooling Tower Fan Motor Replacement – Step-by-Step Guide
1. Preparation (Safety + Verification)
Before touching anything:
Lockout/Tagout
* Shut down the cooling tower.
* Open the motor disconnect and lock it out.
* Verify zero voltage at the motor terminals.
Verify the Replacement Motor
Check that the new motor matches:
* HP / kW rating
* Voltage and phase (e.g., 460V 3Ø)
* RPM (e.g., 900, 1140, 1750)
* Service factor
* Enclosure type — cooling towers usually use
TEFC, TENV, Washdown, or Cooling-Tower Duty / Totally Enclosed
* Shaft size and length
* Mount type: belt drive / gear drive / direct drive
* Rotation direction (CW or CCW when viewed from top)
* Frame size (e.g., 182T, 215T, 324T)
✔️ 2. Remove the Old Motor
A. Disconnect motor wiring
* Label each conductor (T1, T2, T3).
* Note any space heater or RTD wiring.
* Loosen conduit to free the connection box.
B. Remove belts OR uncouple gearbox
Belt drive:
* Loosen motor slide base bolts
* Push inward to release belt tension
* Remove belts
Gear drive:
* Remove coupling guard
* Mark coupling hub positions
* Loosen coupling bolts
* Separate coupling halves
C. Remove mounting bolts
* Support the motor with a hoist, chain fall, or two people.
* Remove the hold-down bolts.
* Lift the motor straight up.
✔️ 3. Install the New Motor
A. Mount the motor
* Place it on the base or motor rail.
* Insert all bolts loosely first.
* Ensure the base is clean and flat (no shims unless needed).
B. Align to gearbox or fan shaft (if not direct drive)
Proper alignment extends bearing and gearbox life.
For belt drives:
* Align motor pulley to fan/gear pulley using a straightedge.
* Set correct belt tension (moderate deflection force; don’t overtension).
For gear-coupled units:
* Perform angular and parallel alignment using:
* Dial indicators, or
* Feeler gauges + straightedge
* Typical tolerance:
* Parallel misalignment < 0.005–0.010"
* Angular misalignment < 0.003–0.005" per inch of radius
(Follow gearbox manufacturer guidelines.)
✔️ 4. Electrical Connections
* Pull conductors into the motor junction box.
* Make new connections per nameplate diagram:
* Low voltage vs high voltage connection matters.
* Tighten all lugs to torque spec.
* Reconnect:
* Space heater
* RTD or thermistor sensors
* Grounding conductor
* Seal conduit to prevent moisture ingress.
✔️ 5. Rotation Check
Before fully coupling or tensioning:
1. Bump start the motor (VERY short jog).
2. Verify:
* Rotates correct direction (usually upward/induced draft).
* If incorrect, swap any two phases.
Only after correct rotation:
* Tighten belts OR fully couple gearbox.
✔️ 6. Final Assembly & Testing
* Secure all guards (belt guards, coupling guards).
* Reinstall fan deck screens if removed.
* Remove LOTO and start the tower.
Monitor for:
* Abnormal vibration
* High motor amps
* Gearbox noise or heat
* Belt squeal
* Any rubbing or misalignment
Amp check:
* Running current should be ≤ nameplate amps adjusted by service factor.
* If amps are high:
* Incorrect rotation?
* Fan blade pitch too aggressive
* Gearbox issue
* Belt tension incorrect
* Air density or tower load high
✔️ 7. After 24–48 hours
Recheck:
* Belt tension (belts stretch during break-in)
* Motor mounting bolts
* Coupling alignment (if gear-driven)
* Motor amps
