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Troubleshooting
The following tables list causes and corrective actions for possible problems with direct fired heater units.
Review these lists prior to consulting manufacturer.
Airflow Troubleshooting Chart
Problem Potential Cause Corrective Action
Fan Inoperative Blown fuse or open circuit breaker Replace fuse or reset circuit breaker
and check amps
Disconnect switch in “Off” position Turn to “On” position
Motor wired incorrectly Check motor wiring to wiring diagram
located on fan motor
Broken fan belt Replace belt
Motor starter overloaded Reset starter and check amps
Remote panel set to “Off” Position Set Remote Panel to “Manual” or
“Auto” Position
Motor Overload Fan rotating in the wrong direction Be sure fan is rotating in the direction
shown on rotation label
Fan speed is too high Reduce fan RPM
Motor wired incorrectly Check motor wiring to wiring diagram
located on fan motor
Overload in starter set too low Set overload to motor FLA value
Motor HP too low Determine if HP is sufficient for job
Duct static pressure lower than design Reduce fan RPM
Insufficient Airflow Fan rotating in the wrong direction Be sure fan is rotating in the direction
shown on rotation label
Poor outlet conditions There should be a straight clear duct
at the outlet
Intake damper not fully open Inspect damper linkage and replace
damper motor if needed
Duct static pressure higher than
design
Improve ductwork to eliminate or
reduce duct losses
Blower speed too low Increase fan RPM. Do not overload
motor
Supply grills or registers closed Open and adjust
Dirty or clogged filters Clean and/or replace
Belt slippage Adjust belt tension
Excessive Airflow Blower speed to high Reduce fan RPM
Filters not installed Install filters
Duct static pressure lower than design Reduce fan RPM
Excessive Vibration and Noise Misaligned pulleys Align pulleys
Damaged or unbalanced wheel Replace wheel
Fan is operating in the unstable region
of the fan curve
Refer to performance curve for fan
Bearings need lubrication or
replacement
Lubricate or replace
Fan speed is too high Reduce fan RPM
Belts too loose, worn or oily Inspect and replace if needed