Frequently asked questions (FAQ)

Bolztherm GmbH, based in Gronau (North Rhine-Westphalia, Germany), specialises in the development and manufacturer-independent distribution of high-quality heat transfer fluids (thermal oils) for industrial plants.

Thanks to lean structures and by avoiding expensive brand premiums, Bolztherm offers technically equivalent heat transfer fluids at a significant price advantage.

Yes, all products comply with common industry standards, including DIN 51522 and DIN ISO 6743. In addition, all thermal oils intended for applications in the food and pharmaceutical industries are NSF-certified and thus approved as HT1 heat transfer fluids.

Yes, Bolztherm GmbH offers comprehensive advice on all aspects of thermal oil – both by telephone and on site at the customer’s premises. We also regularly share our expertise in specialist seminars, training courses and at industry trade fairs in order to support users with practical knowledge.

In principle, different thermal oils can be mixed as long as they are based on the same chemical basis. We will be happy to check and confirm in advance whether they are compatible in your specific case. Please contact us – we will provide expert, application-specific advice.

Yes, Bolztherm offers chemically and technically compatible alternatives to common brands (e.g. Marlotherm SH, Therminol 66 or Shell Heat Transfer Oil S2). Topping up is possible in any ratio without modifying the system. You can find a comparison table under comparison tables.

Bolztherm CW-32 is the recommended successor to Aral Farolin U. Both products are 100 % miscible with each other and offer technically identical performance.

Bolztherm has its own laboratory and offers DIN-compliant analysis services in accordance with DIN 51529 for evaluating and checking the condition of used thermal oils. We also carry out special analyses to determine the silicone oil content in thermal oils from ORC (Organic Rankine Cycle) plants. In addition, we offer individual special analyses for specific, application-related questions.

Used thermal oil samples are analysed in accordance with DIN 51529 "Testing of mineral oils and related products – Testing and assessment of used heat transfer fluids". A distinction is made between mineral oil-based and synthetic aromatic thermal oils. For mineral oil-based thermal oils, all parameters relevant to the standard are determined except for high and low boilers. The analysis covers viscosity, flash point, acid number, carbon residue, water content and high and low boilers.

As part of its analysis service for used thermal oil, Bolztherm helps to prevent unplanned and costly plant shutdowns through regular condition checks and preventive maintenance recommendations. Early identification of contamination resulting from thermal and oxidative decomposition of the heat transfer fluid effectively reduces safety risks, operational disruptions and expensive repairs.

In accordance with the requirements of DIN 4754 and VDI guideline 3033, the suitability for use of the thermal oil (DIN 51529) must be checked at least once a year. Our analysis reports are accepted by insurance companies as well as by official testing organisations.

You request free sample containers from us (approx. 0.5 l aluminium containers) and take the oil sample at a temperature below 80 °C. You then send the sample to our laboratory. The relevant analysis parameters are examined within about two working days. You then receive a detailed analysis report in which the condition of the thermal oil is professionally assessed.

The analysis enables a well-founded assessment of the oil condition, helps to avoid unplanned downtime, increases operational safety and supports the economical use of the thermal oil throughout its entire service life.

The terms are used synonymously, with "heat transfer fluid" being the generic term that covers both heating and cooling media.

Thermal oil is a liquid medium for transporting heat. It can be used even at very high temperatures of over 400 degrees Celsius without evaporating. It is used in particular in industrial processes where steam systems would be technically complex, associated with increased pressure risks or uneconomical due to high operating costs.

A thermal oil system works on a closed-loop principle similar to a domestic heating system. A heater, such as an oil boiler, heats the thermal oil to the required operating temperature. A circulation pump conveys the heated thermal oil through pipelines to the consumers, such as reactors or heat exchangers, where the heat is transferred to the process. The cooled thermal oil then flows back to the heater. The system usually operates without pressure or with only slight overpressure, as long as the operating temperature is below the boiling temperature of the thermal oil used.

The basic design of a heat transfer system is based on a closed circuit. The heat transfer fluid is first heated to the required temperature in a heater. It is then conveyed to the respective heat consumers, where it transfers the stored heat to the process. After releasing the heat, the heat transfer fluid is returned and reheated. This continuous circuit ensures controlled, efficient and uniform heat transfer throughout the entire system.

Thermal oil systems offer a number of significant advantages over conventional steam systems, especially in industrial applications with medium to high process temperatures. A key advantage is that temperatures well above 100 degrees Celsius can be achieved without high pressure. This eliminates the safety requirements and risks associated with pressurised steam systems. Another advantage is very precise and stable temperature control over a wide temperature range, which is particularly important for sensitive production processes. As thermal oil systems operate without water, there is no water-related corrosion. Condensate lines and condensate return systems are also not required, which significantly reduces system complexity. In addition, thermal oil systems require less maintenance. Measures such as descaling or complex feed water treatment, which are essential for steam systems, are completely eliminated.

As a rule, thermal oil does not have to be changed regularly or at short intervals, as is the case with engine oil, for example. In a professionally designed and operated system, a thermal oil filling can easily remain in use for five to ten years. Depending on the oil quality, maximum operating temperature, system design and mode of operation, service lives of more than ten years are possible in many cases. What matters is not a fixed change interval but the actual condition of the oil. This can be reliably assessed through regular laboratory analyses. On this basis, it can be recognised at an early stage whether ageing processes are setting in or whether the thermal oil can continue to be used without restriction. You can find more information about our analysis service here: laboratory analyses

Thermal oils often change colour within a relatively short time during operation: from clear and light to brownish clear to deep black. The speed and intensity of this discolouration depend largely on the operating temperatures and the residence time of the thermal oil in the system. The higher the temperature and the longer the thermal load, the faster the discolouration progresses. However, a visual assessment alone does not allow a reliable statement about the actual condition of the thermal oil. The colour does not indicate whether the thermal oil is already "used up" or can still be used safely. Well-founded statements on the condition of a thermal oil are only possible on the basis of a thermal oil analysis in accordance with DIN 51529. Only the analytical results, supplemented by an expert assessment, allow a reliable evaluation of oxidative ageing, thermal decomposition and other relevant parameters. You can find more information on thermal oil analysis on this page: analysis service.

Continued operation with aged or decomposed thermal oil can lead to considerable technical and safety-related problems. Thermal decomposition products and deposits impair heat transfer, causing heating surfaces to become thermally insulated and to overheat locally. In extreme cases, this can lead to material damage and even tube rupture in heat exchangers. The risk of pump failure also increases due to higher viscosity. Severely oxidised thermal oil in combination with water leads to corrosion. At the same time, operational safety decreases because the flash point of the thermal oil drops, significantly increasing the risk of fire.

The choice of a suitable thermal oil depends largely on the respective application and the evaluation criteria applied. In general, mineral thermal oils are less expensive and usually have a more favourable hazardous substance classification than synthetic thermal oils. However, mineral thermal oils are typically designed for flow temperatures of up to around 300 °C, whereas synthetic thermal oils are also suitable for operating temperatures above 400 °C. In addition to the maximum operating temperature, a careful review of the physical properties is essential to ensure that the thermal oil is optimally suited to the specific application and operating conditions. We will be happy to support you with our technical advice when selecting a suitable thermal oil. Contact us!

Operation above the maximum permissible operating temperature must be classified as critical. Exceeding the specified limit by as little as about 10 K leads to significantly accelerated thermal decomposition of the thermal oil, with ageing processes progressing exponentially. A proven rule of thumb is that a temperature increase of around 10 °C can roughly halve the service life of the thermal oil. This results in a significantly shorter service life and an increased risk of deposit formation. At the same time, the proportion of low boilers increases, which lowers the viscosity and flash point and can promote cavitation in pumps. For safe and economical plant operation, it is therefore advisable to use a thermal oil whose maximum permissible flow and film temperatures are sufficiently above the required operating temperatures.

Water poses a considerable safety and operational risk in a hot oil system. Even small amounts of water can evaporate suddenly in the heater and lead to micro-explosions with dangerous pressure peaks. In addition, water in combination with oxygen promotes oxidation of the thermal oil and corrosion processes within the system. Signs of water in the system are often unusual pump noises, such as rattling due to cavitation caused by vapour bubbles, and visible clouding of the oil. If a relevant water content is detected, suitable measures must be taken immediately. These include controlled boiling out of the system or replacement or regeneration of the thermal oil. At the same time, the cause of the water ingress must be identified and eliminated, for example a leak in a heat exchanger with a water-carrying medium.

Low boilers are low-boiling decomposition products that are formed by thermal cracking of the thermal oil and consist of shorter-chain molecules than the original thermal oil. They evaporate at comparatively low temperatures, lower the flash point of the oil and can cause cavitation, particularly in pumps, through the formation of vapour bubbles. High boilers, on the other hand, are high-molecular, low-volatility decomposition products that are formed under high thermal load. These include tar-like substances and polymeric compounds. High boilers increase the viscosity of the thermal oil and promote the formation of deposits, which impairs heat transfer and can affect plant operation.

There is no generally "best" thermal oil, as the optimal choice always depends on the specific application and the respective operating conditions. For very high operating temperatures of up to around 400 °C, the synthetic thermal oil BOLZTHERM AW-75 is suitable, for example. For applications in the low to medium temperature range, on the other hand, mineral oil-based heat transfer oils such as BOLZTHERM CW-32 can be used. In principle, the best thermal oil is the one that reliably meets the technical and operational requirements of your system while offering an optimal balance of safety, economy and maintenance effort. We will be happy to support you with our technical advice when selecting a suitable heat transfer oil.

Yes, a partial oil change is possible in principle. For example, part of the existing thermal oil (e.g. around 50 %) is drained and replaced with fresh oil. This can raise the flash point and reduce the acid number and carbon residue. Such a step is often used to extend the service life of the thermal oil when a complete oil change is currently not practicable. However, it should be noted that a proportion of the aged oil remains in the system. A partial change therefore does not restore the original condition, but can noticeably improve the relevant oil parameters and support safe continued operation.

The answer is: to a limited extent. Short-term temperature peaks can damage the thermal oil but do not necessarily lead to immediate total failure. The decisive factors are the duration of the overheating and the boundary conditions, in particular whether the maximum flow and film temperatures were exceeded. After such an event, it is strongly recommended to take an oil sample promptly and have it analysed. If the relevant values are still within acceptable ranges, continued operation is generally possible. Nevertheless, local damage may already have occurred, such as coke deposits on the heating surfaces, which later become noticeable through impaired heat transfer. If the overheating was only very brief, the damage is often limited. In the case of longer or repeated exceeding of the permissible temperatures, however, an oil change or at least a partial oil change is generally advisable.

For organic heat transfer fluids, at least an annual check is recommended, as required, among others, by DIN 4754. In addition, an oil sample should be taken and analysed immediately after unusual operating events such as overheating, water ingress or other malfunctions.

During a shutdown in the cold state, the thermal oil usually remains stable and is not subject to any significant thermal decomposition. However, care must be taken throughout the entire shutdown period to consistently avoid contamination, in particular the ingress of water.

Unused thermal oils in their original sealed containers can usually be stored for several years without any problems, provided they are stored properly. This includes cool and dry storage conditions, protection against moisture and the exclusion of direct sunlight. For longer storage periods, especially from around two years, an application-specific check of the thermal oil is recommended before use. With proper storage, however, the quality of thermal oils is maintained over a very long period.

Choosing the right thermal oil is crucial for efficient heat transfer and reliable plant operation. As there is no universal solution, the thermal oil must be matched to the respective application. Important selection criteria are the field of application, the required temperature range, thermal stability, thermal conductivity, specific heat capacity and viscosity. The chemical composition also plays a central role. Compared to water or steam systems, organic thermal oils offer advantages such as lower operating pressures, lower reactivity and reduced tendency to corrosion. Legal requirements must also be taken into account, for example for applications in the food or pharmaceutical industry, where only suitable, tested heat transfer fluids may be used. A careful balance between performance, service life, energy efficiency and costs is therefore essential to ensure safe, economical and long-lasting plant operation.

The maximum film temperature is the highest temperature on the inside of the tube wall of a heater and differs significantly from the measured heat transfer fluid temperature, especially with heated or cooled walls. It represents the point of greatest thermal stress on the heat transfer fluid and is an essential parameter for assessing its service life. The temperature difference between the maximum film temperature and the heat transfer fluid temperature in the same cross-section is also a decisive criterion for the design and evaluation of the heater. The calculation approach described in DIN 4754 applies to fired heaters in which the heat transfer fluid is in the liquid phase and is based on defined design and flow conditions. Alternative calculation methods are permissible if they are supported by test results or mathematical proof.

In indirect heat transfer, the heat is not transferred directly to the material to be heated, but via a transfer medium (thermal oil). This is heated in a heater, conveyed to the consumer and then returned.

Many industrial processes require uniform heating to high temperatures. Direct heating of temperature-sensitive materials can lead to local overheating and thermal decomposition. Indirect heating avoids these risks and has therefore proven to be more reliable.

Organic heat transfer fluids can be used without overpressure up to around 350 °C. At higher temperatures, only moderate overpressure is required, which reduces plant safety requirements and design effort.

Organic heat transfer fluids can basically be divided into two main groups. On the one hand, there are mineral oil-based heat transfer fluids, which are used in many applications due to their good heat transfer properties and cost-effectiveness. On the other hand, there are synthetic heat transfer fluids, which have been specially developed for higher temperature ranges or special requirements and are characterised by high thermal stability and a longer service life.

The group of organic heat transfer fluids includes various hydrocarbon compounds. These include paraffinic, naphthenic and aromatic hydrocarbons. These heat transfer fluids have good thermal properties and are mainly used in medium temperature ranges where reliable and uniform heat transfer is required.

Synthetic heat transfer fluids include aromatic hydrocarbons, alkyl diphenyls, benzyl and dibenzyl toluenes and eutectic mixtures of diphenyl and diphenyl ether. Alkyl diphenyl ethers and partially hydrogenated terphenyls, aliphatic hydrocarbons, silicones and fluorocarbons also belong to this group of substances. These heat transfer fluids are designed specifically for demanding applications and are generally characterised by high thermal stability and good resistance at elevated operating temperatures.

Mineral heat transfer fluids are suitable for applications with moderate operating temperatures and offer a cost-effective, proven solution. However, they reach their limits more quickly at permanently high or strongly fluctuating temperatures. Synthetic heat transfer fluids offer a wider temperature range, higher thermal stability and a lower tendency towards decomposition and deposits. They are therefore particularly suitable for demanding processes and can reduce maintenance effort and operating costs in the long term.

Liquid-phase heat transfer fluids can be used over a wide temperature range and can often be operated without pressure. They enable lower investment costs, as large pipelines, safety valves, steam systems and water treatment are not required. They are also characterised by low maintenance, small top-up quantities and economical operation.

Liquid/vapour-phase heat transfer fluids are suitable for applications with wide temperature ranges and requirements for particularly uniform heat transfer. They allow very precise temperature control and require less heat transfer fluid than pure liquid-phase systems, as parts of the system are filled with vapour instead of liquid.

Various guidelines and regulations apply to the operation of heat transfer systems to ensure safety and proper operation. These include in particular the German Pressure Vessel Ordinance (DruckbehV), the accident prevention regulation VBG 64 and the standard DIN 4754. These regulations define requirements for the design, operation, monitoring and safety of the systems and form the authoritative basis for the safe and legally compliant use of heat transfer systems.

The properties of a heat transfer fluid are largely determined by the molecular structure of the respective chemical compound. This structure influences, among other things, thermal stability, the maximum permissible operating temperature, viscosity and evaporation behaviour. The chemical composition is therefore decisive for the suitability of a heat transfer fluid in certain temperature and application ranges.

Thermal stability describes the chemical resistance of a heat transfer fluid at high temperature. Above a certain temperature, every heat transfer fluid partially decomposes into low-boiling, high-boiling and non-evaporable components. The decomposition rate increases exponentially with temperature – an increase of 10 K roughly doubles it. Thermal stability is determined, among other things, by the chemical structure, purity, temperature and plant-specific factors.

Low boilers lower the flash point and increase the vapour pressure, which can promote evaporation. High-boiling or non-evaporable components increase viscosity, impair heat transfer and increase pressure loss. Thermal stability in the absence of oxygen determines the upper operating temperature. According to DIN 4754, this should be selected so that the heat transfer fluid remains operational for at least one year. Decomposition of a few percent per year is considered economically acceptable.

Above 60 °C, organic heat transfer fluids react exothermically with atmospheric oxygen. This produces oxygen-containing degradation products, including organic acids, as well as high-molecular condensation products. These oxidation products are thermally less stable than the original heat transfer fluid.

Oxidation products can cause an increase in viscosity and accelerated thermal decomposition of the heat transfer fluid. This has a negative impact on plant operation and the service life of the fluid.

New heat transfer fluids that meet their specification must not cause corrosion damage to the materials of the plant. This can usually be confirmed by the manufacturer.

Heat transfer fluids with increased proportions of oxidative degradation products in combination with water, or with heavy contamination, can under certain circumstances trigger corrosion processes on plant components. Regular monitoring of the heat transfer fluid quality is therefore necessary for safe and damage-free operation.

The flow behaviour of a heat transfer fluid is determined by its pour point or solidification point. Below these temperatures, the heat transfer fluid can no longer be used, as its flowability is no longer guaranteed.

When starting up the plant at low temperatures, the flow behaviour of the heat transfer fluid used must be taken into account, for example by using auxiliary heaters. In addition, the known viscosity limits regarding pumpability and heat transfer must be observed to ensure safe and efficient operation.

The performance and mode of operation of a heat transfer fluid are determined by its physical properties. These include density, specific heat capacity, thermal conductivity, kinematic viscosity and vapour pressure. With the exception of vapour pressure, these properties directly influence heat transfer, i.e. the ability of the heat transfer fluid to absorb and release heat. Density and specific heat capacity also determine heat transport in the circuit and are therefore decisive for the design of heat exchangers and the calculation of mass flow, flow conditions and the required pump capacity. For this reason, heat transfer circuits must always be individually matched to the technical data of the heat transfer fluid used.

Heat transfer in the boundary layer of the heat transfer fluid is determined by the heat transfer coefficient, which results from the physical properties of the fluid and design conditions. It increases with increasing flow velocity, density, specific heat capacity and thermal conductivity and decreases with increasing viscosity. As the fluid dynamic and thermal relationships are complex, the property data of the heat transfer fluid must be available for the entire application-specific temperature range to ensure safe and economical planning. The manufacturer or supplier is obliged to provide this data with sufficient accuracy and, if necessary, to provide information on the range of variation and the uncertainty of extrapolated values.

Density is the mass of a substance in relation to its volume. As the temperature rises, the density of a heat transfer fluid decreases because the volume increases at constant mass. This effect must always be taken into account when heating up during plant operation.

The increase in volume of the heat transfer fluid filling when heating up to operating temperature must be absorbed within the heat transfer system by suitable expansion tanks. The change in volume over a defined temperature range can be calculated from the initial volume and the densities at initial and operating temperature and is an important basis for the correct design of the expansion system.

Specific heat capacity is a measure of the heat content of a substance. It indicates how much heat in kilojoules is required to heat 1 kg of a substance by 1 K. As the temperature of the heat transfer fluid rises, the specific heat capacity generally increases.

Together with density, specific heat capacity determines the volume flow required to transport a defined amount of heat at a given temperature difference. Heat transfer fluids with high density and high specific heat capacity allow lower volume flows, which has a positive effect on the dimensioning of the plant. At the same time, higher densities lead to increased power consumption of the pump motor, which must be taken into account in the design.

Thermal conductivity indicates how well a heat transfer fluid can absorb and release heat. High thermal conductivity improves heat transfer at the heat exchanger surfaces and thus contributes to efficient heat transfer. As the temperature rises, the thermal conductivity of heat transfer fluids generally decreases, which must be taken into account in the design and operation of heat transfer systems.

Kinematic viscosity determines the flow behaviour of the heat transfer fluid depending on the flow velocity and influences whether the flow is laminar or turbulent. Low-viscosity heat transfer fluids allow more favourable heat transfer. As the temperature rises, the viscosity of all heat transfer fluids decreases, which increases performance in the intended working temperature range. However, when heating up cold heat transfer fluids, impermissibly high boundary layer temperatures can occur due to high viscosities. For safety reasons, heat transfer circuits should be started up at partial load in such cases until sufficiently low viscosities are reached.

The vapour pressure indicates the proportion of the heat transfer fluid in the gas space above the liquid. Heat transfer fluids with a low vapour pressure and a high boiling range can be operated up to high operating temperatures with low inert gas back pressure. The shape of the vapour pressure curve is decisive for the operating pressure and mode of operation of the heat transfer system.

The safety data sheet provided by the manufacturer contains all the information required for the safe and legally compliant handling of heat transfer fluids. This includes information on the chemical character, toxicological and ecological properties, physical and safety-related parameters such as flash point and ignition temperature, as well as information on transport, storage, handling, personal and technical protective measures and behaviour in the event of accidents and fires. It also includes legal classifications under the German Hazardous Substances Ordinance.

Safe and trouble-free operation of heat transfer systems requires regular maintenance. The plant manufacturer must provide the operator with operating and maintenance instructions. Personnel entrusted with maintenance must be professionally instructed and appropriately trained.

According to DIN 4754, the heat transfer fluid must be tested for continued usability as required, but at least once a year (see also DIN 51528). A test is particularly necessary in the event of irregularities in plant operation that indicate damage to the heat transfer fluid. The sample (approx. 1 litre) must be taken from the main flow, via a sample cooler in hot systems or at temperatures below 80 °C. The sample container must be closed immediately and kept closed until the test. The sample must be clearly labelled, including the operator’s address, plant designation, heat transfer fluid (trade name), plant volume, operating hours of the filling, operating temperature and sampling date. The continued usability of the heat transfer fluid must be confirmed in writing by the testing laboratory.

The requirements of DIN EN 13445 or the AD 2000 code apply to the construction of heaters, vessels and heat consumers. Pipe materials must be selected in accordance with DIN EN 10216 or DIN EN 10217; the material quality must be verified at least by a test report 2.2 in accordance with DIN EN 10204, and by an inspection certificate 3.1 for heat-resistant steels. Suitable heat-resistant steel, for example cast steel in accordance with DIN EN 10213, must be used for pump and valve housings. Up to 350 °C, spheroidal graphite cast iron in accordance with DIN EN 1563 is also permitted. Cast iron with lamellar graphite in accordance with DIN EN 1561 (EN-GJL-250) may be used up to 200 °C, DN 200 and 10 bar, but only for pumps and valves that are not used for heating or cooling and in which the heat transfer fluid is not heated above its boiling point at atmospheric pressure. Other materials may be used if their suitability has been proven for the first time by an expert opinion from an independent body; in particular, the temperature behaviour of strength and creep behaviour must be taken into account. Suitable seals include graphite seals, metal soft-material seals, metal seals and welded lip seals.

The manufacturer or supplier of the heat transfer fluid must specify the permissible flow temperature and all data required to assess its suitability for use, at which the heat transfer fluid remains usable for at least one year. The prerequisite for this is that the heat transfer system is designed in accordance with the standard (DIN 4754) and operated properly. In addition, all physical properties and chemical characteristics of the heat transfer fluid relevant to construction, operation and safety must be communicated to the plant manufacturer and the operator. The maximum permissible film temperature, which must not be exceeded at any point in the system, must also be specified.

Fired heaters must be operated in boiler rooms with permanent ventilation. The required air flow rate is at least 0.5 m³/h per kW of total nominal heat output. The requirements of DIN 4754 are considered primary explosion protection measures. Additional electrical protective measures are not required. Drip trays can be made of metal or other suitable materials. When designing the supply and exhaust air openings, the requirements of the respective state building regulations and the plant-specific conditions must be taken into account.

Pump housings must be designed for at least nominal pressure PN 16. Shaft seals must have proven themselves in use or their suitability must be demonstrated. With cooled bearings or shaft seals, it must be ensured that a warning device is triggered if cooling fails. Leaking heat transfer fluid must be safely drained and collected and is generally not reusable. In addition, impermissibly high forces or moments from the pipelines must be prevented from acting on the pump. For applications below the initial boiling point, pumps with an extended cooling section have proven themselves. When operating above the boiling point, sealless pumps such as magnetically coupled pumps or canned motor pumps are often used.

For applications in the food industry, for example in bakeries, Bolztherm provides special food-grade heat transfer fluids, including BOLZTHERM FOOD GRADE 700. These products meet the relevant food law requirements, including FDA 21 CFR, and are also NSF-certified. BOLZTHERM FOOD GRADE based on water glycol and BOLZTHERM CT-12 are also NSF-certified.

Thermal oil is a liquid heat transfer fluid with a high heat capacity that stores and transfers heat particularly evenly. In the baking process, it ensures stable temperatures without fluctuations. This results in a crispy crust, an even crumb and a perfectly baked base in every batch.

The thermal oil is heated in a boiler and circulated through the heating surfaces of all oven decks in a closed circuit. The heat is released homogeneously, allowing even baking without reheating times and keeping oven performance constant.

Thermal oil enables static radiant baking without air circulation. This improves crust formation, preserves the natural moisture of the baked goods and retains aroma and freshness. At the same time, the high thermal stability allows continuous production with high energy efficiency and minimal maintenance.

Baking with thermal oil enables very even and stable heat transfer with a high proportion of radiant heat. This results in even crust formation, good heating right through to the core of the product and consistent baking results. The high thermal inertia allows continuous production processes with high energy efficiency and minimal temperature fluctuations.

Deck ovens with thermal oil heating enable particularly even and stable heat distribution across all baking plates and throughout the entire baking time. Thanks to the high heat storage capacity of the oil, the temperature remains constant even under high load, resulting in even porosity, good crust formation and reproducible baking results. At the same time, thermal oil technology works energy-efficiently, as heat losses are minimised and there are no strong temperature fluctuations.

Thermal oil deck ovens offer very even heat distribution and high energy efficiency. The heat is transferred via hot oil that circulates under the baking plates, enabling stable baking performance across the entire batch. Cyclotherm ovens work with hot gas that circulates in closed ducts under the baking plates and are particularly suitable for artisan breads with demanding temperature profiles, such as rye or mixed rye breads. Electrically heated deck ovens allow each deck to be operated independently and are ideal for smaller businesses that want to bake different products at the same time or do not have access to gas.