Immersion heaters—​​also referred to as bayonet heaters—are electric-powered direct contact heating devices used to heat material inside of a container. They are available in many designs, configurations, and temperature ranges to suit different heating needs. The following article provides an overview of immersion heaters, outlining how they work, some of their key benefits, the types available, and typical industrial applications.

How Do Immersion Heaters Work?

During heating operations, the heating element of the immersion heater is immersed directly into the unprocessed material either through the top of the container or a fitting inserted into the side of the container. Once the element is in position, the heater is turned on. As the electricity runs through the device, it heats the element, which then transfers the heat to the surrounding material. The amount of time the heater takes to heat all the material in the container to the desired temperature depends on the total quantity of material in the container and the power level of the heater.

Benefits of Immersion Heaters

When used in the industrial facilities, immersion heaters offer a number of benefits, including:

High Heating Efficiency

Immersion heaters are an efficient and effective method of heating large amounts of material. Compared to other metallic or non-metallic heating elements, ultra-high-temperature ceramic immersion heaters offer even greater efficiency. They can heat up to 1200° C and achieve up to 98% heating efficiency in water.

Low Maintenance​ Requirements

Immersion heaters can run near-continuously with very little maintenance. This quality reduces their overall operational costs and the amount of downtime required for upkeep and repair operations. 

Broad Versatility​

Immersion heaters are suitable for heating a wide variety of different materials. This versatility is particularly useful for facilities that must heat different materials as they don’t need to invest in a different heater for each material.  

Types of Immersion Heaters

Immersion heaters are generally manufactured in one of two styles: 

  • Flange-mounted immersion heaters feature hairpin tubular heating elements that are welded to a flange component. When installed, the flange component is matched to a flange that is welded into the tank’s wall or nozzle. This type of immersion heater is often used to heat liquids in holding and storage tanks. It readily accommodates monitoring and control operations. The flange components are available in ANSI or custom designs.
  • Pipe thread heaters, also known as screw plug heaters, have hairpin bent tubular heating elements that are welded to a screw plug component. This type of immersion heater is suitable for freeze protection and process water heating operations in circulating fluid systems. Similar to flange-mounted immersion heaters, it is easily controlled and monitored. The pipe thread fitting generally complies with National Pipe Tapered (NPT) thread standards.

Typical Industrial Applications of Immersion Heaters

Immersion heaters find use in a wide range of industrial, commercial, and residential applications. They are often employed as electric water and other fluid heaters, air conditioners, ignition devices, instant hot water taps, rectors, steam generators, and more. 

Within the industrial sector they are generally utilized by various plants and facilities, such as wastewater treatment centers, for one of the following: 

  • Large-scale heating and/or melting operations
  • Process fluid temperature regulation
  • Freeze protection

Immersion Heaters From Pelonis Technologies

At Pelonis Technologies, we offer ultra-high-temperature ceramic immersion heaters suitable for a wide range of applications in both the industrial and commercial sectors. Our heaters demonstrate high thermal conductivity and greater heating efficiency (for both gaseous and liquid materials) than other metallic and non-metallic heating elements available in the market today. Some of the key features include: 

  • Self-regulating
  • Can be used in air or water
  • Corrosion resistance (to acids and bases)
  • Minimal risk of water heater scale deposits
  • Electric insulation: <10 mA (even when broken) 
  • Maximum heating range: up to 1200° C in 40 seconds
  • Heating efficiency: up to 98% (in water) 
  • Watt density: <70 W/cm2 (in water) and <25 W/cm2 (in air)


For additional information about our immersion heaters, visit our product catalog or contact us today. 

Let us put our experience and expertise to work.