Image Credit: Thermon Manufacturing Co. | Tyco Thermal Controls



Trace line heaters are flexible, insulated cables that are heated with electricity or re-circulated fluids. They are used to prevent liquids in pipes from freezing, or to reduce heat loss in piping.  Trace line heaters differ in terms of cable shape, cable size, and maximum temperature.




Trace Heating - The Basics

Video Credit: TraceHeatingUK1



Selection Criteria


When searching for trace line heaters, cable configuration, cable insulation and maximum temperature are the most important parameters to consider. Other considerations include fuels and/or energy sources, RoHS / WEE compliance, and various features.


Cable Configuration 


Typically, the cross-sectional geometry of the straight (uncoiled) cable is round, square or rectangular. Coil width and uncoiled length are important dimensional specifications to consider.



Round cable - The cross-sectional geometry of the straight (uncoiled) heating cable is round.

Square or Rectangular cable - The cross-sectional geometry of the straight (uncoiled) heating cable is square or rectangular. 

Coil Width - The coil width is the longest dimension measure across a cross section perpendicular to the length of the cable.

Uncoiled Length - Uncoiled length is the length of a straight cable.



Cable Insulation


Trace line heaters differ in terms of insulation options. Although heaters without insulation are available, these devices are not particularly energy-efficient.  Typically, suppliers carry trace line heaters with ceramic, fiberglass, magnesium oxide, mica or mineral insulation, or a fluoropolymer. Each type of insulation offers different features. Some heaters may be available with multiple insulation options.

  • Trace line heaters with no insulation have a lower profile and are useful in areas where space is at a premium, but they are not energy efficient.


Maximum Temperature


The maximum operating or sheath temperature for trace line heaters is the highest temperature that the device's protective cover may attain. 


 Note, however, that this is not the maximum temperature that a heated substance can reach.  

Fuels and/or energy sources

Trace line heaters are primarily powered electricity or re-circulated fluids.  Electrically powered trace line heaters are typically referenced as heat tracing cables.  The most common thermal fluids used in other types of trace line heaters are steam and hot water.


Electrically Powered



Heating Cable

Image Credit: Tyco Thermal Controls




Electrically powered trace line heaters may use either single-phase or three-phase power. Typically, these devices use alternating current (AC) instead of direct current (DC) and differ in terms of watt density. When listed as a range or maximum amount, watt density provides a good measure of how quickly the trace line heater can transfer heat to a heated surface. 




To calculate watt density, suppliers divide the available wattage by the heated surface area. 


Re-circulating Fluids





Steam Tracer

Image Credit: Thermon Manufacturing Co. 


Re-circulating fluids used in trace line heaters are typically steam or hot water. In some applications where steam or hot water supply is readily available, these types of trace line heaters are an environmentally friendly and cost effective method of heating a vessel, pipe or other surface. 


RoHS / WEEE Compliance

RoHS Compliant

Image Credit: Industrial Safety Solutions


WEEE Compliant

Image Credit: EPM Global Services 






  • Self-regulating cables incorporate a temperature sensing device and are used to maintain temperature limits in order to prevent freezing or over heating of process fluids.
  • Corrosion resistant trace line heaters are made of corrosion-resistant materials and suitable for use in a corrosive or chemical environment.
  • Trace line heaters designed for hazardous location heaters are for use in places where there is a risk of fire or explosion. Underwriters Laboratories (UL) and other organizations rate these devices. 
  • Some trace line heaters have an integrated, adjustable or preset thermostat. The thermostat regulates the temperature of the heated object.



Thermon Manufacturing Co. - The Relative Merits and Limitations of Thermal Fluid, Electric and Steam Heat Tracing Systems


Straight Line Inulation I, L.P. - Heat Tracing