We are taking the opportunity afforded by Dr. Jürgen Sterlepper’s appointment to BBT Thermotechnik GmbH's Executive Management with effect from January 1, 2006 to introduce him and to ask him about a subject for which he and his development team will mainly be responsible: the selection of the best material.

Question: Mr. Sterlepper, our readers would undoubtedly be interested in having a peek at the CV of the future Executive Management member.

Dr. Jürgen Sterlepper: With pleasure. I studied mechanical engineering, specialising in heating technology, at RWTH Aachen University and completed my doctorate in 1992 in what was then the Department for Applied Thermodynamics. After that I worked for a university spin-off company as a development consultant for the heating sector where I handled projects for Buderus among others.

Question: And that’s how you came to join Buderus in 1995?

Dr. Jürgen Sterlepper: Yes, as head of Development Gas-Fired Boilers at the Lollar plant initially. Four years later I took over Sales Engineering where I was responsible for technical customer support in all Buderus branches within Germany and for advising planning consultancies on heating technology issues.

Question: You don’t often come across an R&D person with that much sales responsibility.

Dr. Jürgen Sterlepper: You’re right, but that’s what I wanted to do and I learned a great deal about markets, by which I particularly mean about the needs of specifiers in the medium and large boiler sector and of planning consultancies. I still visit our branches and customers as much as possible.

Question: One of the markets you had an opportunity to get to know was the UK. How did that come about?

Dr. Jürgen Sterlepper: As part of the merger of Bosch's former Thermotechnology Division and Buderus, I was seconded to Worcester. The new legislation in the UK meant that the production of gas wall-hung non-condensing boilers had to be converted to condensing appliances. This impacted on the entire product range. Everything had to happen very quickly, without compromising product quality and reliability. In doing so, we significantly grew our market share. It was an enjoyable time and expanded my horizons.

Question: So sales and foreign experience were then added to R&D and heating technology, the fields which had defined your career to that stage.
To move on to the issue of materials: BBT Thermotechnik GmbH operates an application-oriented multi-material strategy. This means that the appropriate material is used for every application in the manufacturing process. What are the most important materials?

Dr. Jürgen Sterlepper: There’s no straightforward answer to that. It always depends on the interplay of the material and the design. The design has to be right for the material and make use of its specific advantages. For that reason, it is never a case of a material being innately good or bad. It always has to be viewed in association with the design and application field.
We use aluminium, for example, especially for wall-hung condensing boilers up to 120 kW. Grey cast iron is the preferred material for floor-standing boilers up to 1200 kW. Standard and special steel and copper also play an important role.

Question: How is the decision reached on the selection of materials and possible combinations?

Dr. Jürgen Sterlepper: The respective requirements of the different regional markets and market segments have to be satisfied. We have many years' international experience in terms of both engineering and market knowledge. Heat exchangers have been developed and manufactured at Buderus for over a hundred years. Nefit was the first manufacturer, some 25 years ago, to install aluminium heat exchangers in wall-hung condensing boilers, which helped to achieve the breakthrough for condensing technology.
Since then, over three million aluminium condensing boilers have been sold by BBT Thermotechnik GmbH as a whole.

Question: Where do developments in materials technology go from here?

Dr. Jürgen Sterlepper: No quantum technological leaps are expected. In the heating technology sector we are already close to the physical limits, and so we can only expect evolutionary steps with traditional heat exchangers, for example in terms of surface treatment. The use of plastics for boiler and system components will increase, for instance for components related to the heat exchanger and in flue gas systems. I intend driving such refinements forward.

Question: Does BBT Thermotechnik GmbH actually have specialists for each material and each application?

Dr. Jürgen Sterlepper: Yes, as befits the market leader, BBT Thermotechnik GmbH has about five hundred R&D staff worldwide. The customer can rely on our systems expertise. We know what can and can’t be combined, and not only in the field of materials. For example, we ensure that a heat exchanger is designed such that it can work with varying water, gas or oil qualities and can also cope with different ambient and operating conditions. Our skills in the field of control technology also help here in meeting all the various requirements. In view of rising oil prices, products for renewable energies are becoming more and more important. Here, too, we are much in demand because of our control and systems expertise.
Incidentally, as the Thermotechnology division of Robert Bosch GmbH, we can call on the expertise of the corporate R&D department and share in the latest materials research data. Very close co-operation and a major degree of knowledge transfer take place.

Question: What’s the story with environmental protection in Development?

Dr. Jürgen Sterlepper: The Development department is also certified in accordance with environmental standards. This means that specific requirements are laid down on the environmentally compatible development and manufacture of our products. Our materials are also eminently capable of being recycled. The mere fact that our industry can be seen as the role model for the production of durable consumer goods is, in itself, a contribution to the environment. Our heat exchangers are designed to deliver a service life of 40,000 operating hours, i.e. twenty years.