Application Note: Troubleshooting Leister Air Heaters

Leister’s industrial air heaters are very robust but there are times when they show troubling symptoms. This application note outlines some of the most common symptoms that you might see and how to go about solving the underlying problem.

Symptom

Possible Cause

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There is no heat

• Element may be damaged – check for cracks
  
• Power is not connected
  
• If using an external temperature controller, check control signal settings and connections
  
• Be sure the tool is connected to correct voltage. Connecting a voltage greater than the rated voltage will damage the tool, often beyond repair. 
  

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Not getting to temperature

• Be sure the tool is connected to correct voltage. Having a lower voltage than the tool is rated for will lower the maximum possible temperature.
  
• If using an external temperature, check that settings are correct. 
  
• If the tool has internal electronics, make sure any possible settings are correct.
  
• Be sure that the air flow is not too high for the power rating of the tool. The heater will give specification on the maximum possible temperature attainable but this is dependent on the amount of air flow.
  
• Check for thermocouple issues such as incorrect type of thermocouple or thermocouple wire

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Only part of the element is glowing

• If the heater is rated for three phase voltage be sure that it hasn’t been connected to single phase
  
• Check element for damage. Some elements are divided into sections such that if one section is damaged the others will still work. 
  

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Heater is overheating

• There isn’t enough airflow. Check the hoses and blower filters to make sure nothing is blocked. Keep hose as short as possible.
• Be sure any nozzles attached to heater aren’t causing too much back pressure. This doesn’t allow the hot air to escape.
• If using an external temperature controller, check that settings are correct. 
• If using an external thermocouple check the placement. A thermocouple placed too far from the heater or knocked out of the air stream will cause the heater to over work to get to set temperature.
• Intake air is too hot

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Getting uneven heat through two heaters

• Check that the hose to each is the same length or if there is a blockage to one of the heaters
  

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Sparking at air outlet

• Mica tube flaking - replace immediately 

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​Originally published: 04/27/2015