Flanged Heaters/Immersion Heaters

Our engineered flanged heaters are designed for direct contact with water, solvents, oils, process solutions and gases.

Immersion heaters are mounted sideways into the vessel, preferably close to the bottom. Since the elements are fully immersed, virtually 100% energy efficiency is achieved.

Special elements are available for heating of corrosive solutions, highly viscous oils, high pressure or hazardous areas.

Typically a number of U-shaped heating rods are welded to a threaded boss or a flange. The terminations are usually covered by a termination housing.

Design criteria:

Medium: Oil, sugar based liquids (e.g. fruit juice) and other solutions may degrade if subjected to a high element temperature. This can also lead to carbon built-up on the element, hindering heat transfer and eventually causing element failure. For these liquids a low watts density is advisable.

Flammable substances: Fuels, oil and generally combustible substances must be heated with care. The element temperature and the operating temperature of the system must be maintained below the flashpoint to prevent fire or explosion. Ex-rated elements are therefore specifically designed and equipped with a thermostat to limit element temperature. In addition, approved temperature and pressure control equipment must be used.


  • Hot water tanks
  • Electrically heated boilers (better control than with gas or coal burners)
  • Control of bulk oil temperature in lube oil reservoirs (improves lubrication)
  • For heavy weight oil (for better flow, easier pumping, increased combustion efficiency)
  • Industrial water tanks, vessels and process piping
  • Cleaing and rinsing tanks
  • Heat transfer sysems
  • Circulation heating
  • Steam superheating
  • Heating of air or gas

View a list of our standard flanged elements.


Example of a specific client requirement:

A client in the packaging industry requires air to be heated via a heat exchanger in a hazardous environment using silicone oil for the primary heating circuit.


  • Pump optimisation for high temperatures
  • Controlling temperatures at varying flow rates
  • Selection of heat source for safe operation


Thermon SA engineers designed and manufactured this diathermic silicone oil heater which is supplied with a special high temperature pump system and safe, low surface temperature elements.
The control panel incorporates PID controllers with solidstate realays for fast response to changing flow rate and ramping of temperatures during start up.

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Please describe your existing or proposed process in as much detail as possible.
Please describe any inefficiencies or specific requirements of the existing system if applicable.
Please describe the optimal results expected from the new system in as much detail as possible.
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