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Table 50 —
Humidifier Troubleshooting (cont)
AHU —
Air-Handling Unit
Table 51 —
Unit Troubleshooting
SYMPTOM
POSSIBLE CAUSES
POSSIBLE REMEDIES
Condensate in unit
The humidifier is too large.
Verify humidifier capacity versus air volume.
There is a high limit controller fault.
Verify that high limit controller is working. If necessary, correct problem.
Evaporation distance is too short.
Verify and, if necessary, correct evaporation distance to obstructions or
elbows.
Steam valve is leaking.
Verify steam valve is not leaking. If necessary, correct leaking steam
valve.
Steam leaks from P-traps
The trap height is incorrect.
Ensure that height of trap exceeds the static pressure of the duct/AHU,
especially if under negative pressure.
Valve sizing is incorrect.
Check valve sizing to maximum manifold capacity. If necessary, resize
valve within manifold capacity.
There is excessively high steam pressure.
Check that inlet steam pressure does not exceed humidifier capability.
SYMPTOM
POSSIBLE CAUSES
POSSIBLE REMEDIES
Motor fails to start
Power line open
Reset circuit breaker.
Improper wiring or loose connections
Check wiring and connections.
Overload trip
Check and reset overload.
Mechanical failure
Inspect motor and drive for operation and/or damage.
Improper current supply
Check rating plate against actual supply voltage. Contact
power provider for adjustments if needed.
Motor stalls
Open phase
Check line for open phase.
Overloaded motor
Reduce motor load or replace with larger motor.
Low line voltage
Check supply line, correct voltage.
Excessive vibration
Bearing/shaft misalignment
Check and align bearing set screws.
Shipping blocks/spacers not removed
Remove shipping blocks/spacers.
Excessive belt tension
Adjust belt tension.
Drive misaligned
Align drive.
Bearing(s) hot
Grease not evenly distributed after lubrication
Allow unit to cool down and restart.
Over-lubrication
Clean and purge excess grease.
No lubricant
Check bearings for damage and apply lubricant.
Misaligned bearing
Check shaft level and reset alignment.
Motor does not run at
full speed
Low voltage at motor terminals
Check supply voltage and correct voltage loss.
Supply wiring to motor too small
Rewire with properly sized wire.
Motor overheats
Overloaded motor
Reduce motor load or replace with larger motor.
Motor fan is clogged, preventing motor cooling
Clean motor fan.
Excessive motor noise
Mounting bolts loose
Tighten bolts.
Rigid coupling connectors
Replace with flexible connectors.
Worn motor bearings
Replace bearings and seals.
Fan rubbing on housing
Adjust housing.
Motor runs and then slows
Partial supply voltage loss
Check for loose/dirty connections.
Verify supply voltage.
Excessive motor bearing wear
High load due to over-tensioned drive
Check belt tension and load.
Excessive overhung load caused by a small
diameter motor sheave
Replace with larger sheave.
Loose Fan Belt
Improper motor position
Adjust tension.
Worn sheaves
Replace sheaves.
Worn or damaged belt
Check sheave alignment and replace belt(s).
Drive Noise
Sheave(s) not tight on fan/motor shaft(s)
Tighten sheaves.
Belts contacting guard(s)
Adjust or tighten belt guard mounts.
Belts too loose or too tight
Adjust belt tension.
Belts and sheaves mismatched
Install proper belts.
Belts not length matched (multiple belt set-up)
Install matched belts.
Misaligned sheaves
Align sheaves.
Belts worn
Replace belts.
Belts dirty or oily
Replace belts.
No Power to Unit
Power switch in wrong position.
Verify SPP power switch handle is in the proper position.
Circuit breaker tripped
Reset SPP circuit breakers.
Fuse blown
Inspect SPP fuses.
