Energy Tech Laboratories MR212 Manuale Utente

 

21

The following tables list causes and corrective actions for possible problems with direct fired heater units.  
Review these lists prior to consulting manufacturer. 

Problem 

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