Thermal Oil / Thermal Fluid




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Oil Replaces Water and Steam

Water and steam are typically used as heat carriers in industrial heating systems.

In industrial heating systems a high temperature level is often a necessity for achieving the required high efficiency. When using steam or pressurised water these high temperatures correspond very high operating pressures. Such pressurized steam or water systems can be very controversial and expensive, however that has been the situation for centuries - and has thus been general accepted to deal with - technically and economically.

Today there are alternatives - high temperatures does not necessary need high operating pressures!

In thermal oil heaters a special oil are instead as heat carrier (heat transfer oil), operating at atmospheric pressure up to 300°C. For comparing this to water and steam, it would require a steam pressure of 85 bar to obtain this temperature.

There are several advantages by using a thermal fluid compare to e.g. steam systems.

The most obvious advantages are:

  High operating temperatures - up to 300°C at atmospheric pressure.
  Adjustable set-points of operating temperatures.
  No equipment for pre-treatment of boiler feed water to maintain.
  No heat loss due to hot condensate and flash steam - high efficiency and better operation economy.
  No risk of corrosion and no risk of freezing damages.
  Low maintenance costs
  Quiet in operation with no steam stroke or flash steam / condensate noise
    Easy to operate (does not require
steam boiler certified staff)

The Safe System

A correct and safe system design is very important for any high temperature system. This is ensured by using only experienced suppliers for the heaters and accessories - and of course also the contractors for building up the whole system on site. The engineers specialising in thermal oil systems, knows about all those details - the features, updated technical knowledge of possibilities, options, - but also the threats particular when dealing with these high temperature process heating systems.


Thermal oil heaters can be delivered in horizontal execution (with low height), or in vertical execution (occupying limited floor space). They are typically delivered complete, insulated and equipped with burner, armatures, instrumentation, safeties and control panel - and with full documentation including necessary certificates.

The heaters are made with winded-up coils made of seamless tubes. The thermal fluid is heated during the flow through the tube coil. The heat is transferred to the fluid as radiant heat in the combustion chamber, where the inner cylindrical tube coil and a flat tube coil forms the chamber wall and the bottom respectively. Consequently refractory concrete can be avoided. The combustion gasses are hereafter cooled in the outer convection part, as the gasses are led between the space of the two tube coils and the outer boiler shell - in another two pass.

The thermal design with tube coils ensures a modest volume of the thermal fluid relative to the size of the heater, and it also allows unlimited thermal expansion due to the high fluid temperature.

The heater and the thermal oil heating system should be designed and equipped according DIN 4754 and in EU the units will CE-marked accordingly. The pressure vessels parts are consequently made according PED 97/23/CE.

The heaters are normally provided by international recognized and high quality burner brands - for natural gas, light fuel oil, heavy fuel oil and combinations (dual fuel). Demands for special burner designs can be meet and adapted in the heater design.

All thermal oil heaters must be carefully checked, controlled and function tested prior to dispatch from the workshop and are delivered with a full set of documentation comprising drawings, diagrams, data sheets, specifications, part list and instruction manuals.

Considering all above, it is therefore strongly recommended that the chosen brand is from a experienced and well reputated manufacturer. Do never compromise in quality, it can be both fatal and expensive !



Beside the standard design, thermal oil heaters can also be delivered in different special executions - for instance following variations:

  Electrical heated and EX-design (ATEX)
  Flue gas (exhaust gas) heated
  Steam heated thermal oil
  Combination of heat sources
  Container solutions
  Open trailer (mobile) solutions
  Complete skid-mounted units
  Complete unassembled "Lego" system
  Material in stainless steel
  Any customised design




This article is made by AB&CO and is the property of AB&CO. It must not be copied in part or in whole without written permission by AB&CO.


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