Kelvion Safety Heat Exchangers GmbH

Kelvion Safety Heat Exchangers GmbH

formerly GEA Renzmann & Grünewald GmbH


Established in 1948, Kelvion Safety Heat Exchangers GmbH is a member of the globally operating Kelvion Group, which is based in Bochum, Germany. The companies of the group supply components, machinery and equipment for process and thermal technology applications.

Kelvion Safety Heat Exchangers GmbH has been successfully manufacturing heat exchangers and other process equipment for more than 60 years. The focuses of the company’s wide range of products and services are the business segments Transformer Cooling Systems and Double Tube Systems.

Based on our long years of experience and our organically developed expertise we recommend ourselves as a global supplier of equipment and components which are both economically efficient and environmentally compatible.

Our most important asset is our employees.

In today’s competitive marketplace, know-how is one of the most precious commodities that a company can have. An environment where employees share the available knowledge, generate new knowledge and thus learn from each other continuously can give a company a significant competitive advantage over its rivals.

Thanks to our qualified and highly motivated employees we can now look back on a 60-year long, successful company history.

With international standards on the safe side

Kelvion is committed to customer-oriented service. Responding to our customers’ every need is a matter of course for us.

We provide the following specific services:

  • Expert consulting on all questions relating to heat exchangers
  • Maintenance, cleaning and repair of the equipment and components supplied by us
  • Supply of spare parts incl. installation, if requested
  • Repair services by skilled professionals
  • Performance measurements of heat exchangers
  • Noise measurements, for example of transformer oil air coolers
  • Studies of transformer oil pump characteristics (characteristic curve, delivery head, etc.)
  • Flushing of transformer oil coolers with transformer oil and performing oil analyses to prove the successful cleaning
  • Modernization and performance improvement of existing transformer oil cooling systems
  • Condition assessment of heat exchangers using proven methods

Customers requirements and quality work are most important to us

A team with the following testing equipment is available to you for testing and servicing our products:

Electrical operation test of transformer oil air coolers

The electrical operation test of transformer oil air coolers includes checking the sense of rotation, insulation resistance, and power consumption. For this purpose, the fans are cabled and each fan is subjected to a trial run.

Noise measurement of transformer oil air coolers

Noise measurement of transformer oil air coolers is performed in accordance with DIN 45 635, using a sound pressure instrument. The sound pressure level acting on different measuring points is measured at a distance of 2 m. Readings are taken at two different measuring planes. The results are A-weighted. Where measuring conditions are difficult (e.g. complete cooling systems), the sound intensity method can be used.

Oil sample

The solids content (particle count) of the transformer oil is determined using the sample feeder PZG-4. If the measured maximum solids content of the oil is 5,000 particles/100 ml (particles smaller than 5 microns are ignored) the item tested is released for further production.

Performance test/measuring stand for heat exchangers

The transformer oil cooler performance test stand was developed for water cooler quality control. The objective was to optimize heat exchanger designs and make heat exchanger operation safer. The test stand was recently extended so that transformer oil air coolers can be tested as well. The test stand allows the complete range of transformer oil air coolers and a large part of the water cooler range to be tested. The test covers temperature, pressure and flow rate readings. With this test stand, we can meet our customers‘ demand for tests under specific operating conditions. For testing alternative materials, for instance, the test stand has proved to be indispensable.

Transformer oil pump test stand

The pump test stand was developed for measuring new pump types and performing quality control tests. Taking measurements and analyzing their results systematically is the basis for continuous product optimization. In problematic cases, pumps can be measured and optimized, if necessary, at our plant under near-operating conditions. An additional water cooling system allows the pumps to be tested not only at operating temperatures, but at lower temperatures as well. Specific customer requests, for example for operation tests using alternative insulating fluids, can also be met.

Pressure and flushing test stand for heat exchangers

This test stand is used when large flow rates are called for. It serves for flushing and pre-cleaning repaired coolers as well as facilities and coolers with unknown oil fillings. Such systems can thus be prevented from being contaminated with spent/extraneous oil.

Kelvion Safety Heat Exchangers GmbH (formerly known as GEA Renzmann & Grünewald GmbH)  was established by Karl Renzmann (engineer) and Karl Grünewald (mechanic) in Weinheim (near Heidelberg) on 18 October 1948. The company’s main products were water coolers and oil recirculating pumps for power plant transformers.

During the first two years, the staff increased from five to 30. Due to its rapid growth, the company successively relocated its production operations between 1956 and 1959 to a larger site in Monzingen/Rhineland-Palatinate.

In 1969 the company was sold to GEA Luftkühler GmbH. Its range of products was significantly extended by the addition of transformer oil coolers and galvanized steel finned tube heat exchangers. The company’s success increased as well, so that a further extension of its production capacity became necessary. In 1992, the company constructed and moved into a new production and administration building in Monzingen.

in 2015, GEA Renzmann & Grünewald GmbH changed the name to Kelvion Safety Heat Exchangers GmbH.

Thanks to the cooperation within the Kelvion Group, the company is in a position to use also production locations in Poland and China, where this offers advantages for its customers.

Today, Kelvion Safety Heat Exchangers GmbH designs and manufactures modern cooling systems for transformers, shell-and-tube heat exchangers for heating and cooling air or other gases as well as transformer oil pumps in a standard and weight-reduced design.

Contact persons

Contact person
Contact details
Managing Director
Marwin Christ
Phone: +49 6751 / 9303-120
Fax: +49 6751 / 9303-159
Executive Assistant
Petra Park
Phone: +49 6751 / 9303-103
Fax: +49 6751 / 9303-100
Plant Director
Jens Rissmann
Phone: +49 6751 / 9303-192
Fax: +49 6751 / 9303-200
Sales Director
Wolfgang Siffring
Phone: +49 6751 / 9303-230
Fax: +49 6751 / 9303-179
Transformer Cooling Systems
Ina Falk
Phone: +49 6751 / 93 03-161
Fax: +49 6751 / 93 03-169
Double Tube Systems
Jürgen Venter
Phone: +49 6751 / 9303-170
Fax: +49 6751 / 9303-179
Innovation Management
Paul Dumcke
Phone: +49 6751 / 9303-261
Fax: +49 6751 / 9303-100
Human Resources
Robert Pafferath
Phone: +49 6751 / 9303-115
Fax: +49 6751 / 9303-109
Quality Management
Jörg Bubinger
Phone: +49 6751 / 9303-292
Fax: +49 6751 / 9303-139
Ronald Dreher
Phone: +49 6751 / 9303-183
Fax: +49 6751 / 9303-169
Sven Pleines
Phone: +49 6751 / 9303-114
Fax: +49 6751 / 9303-119
Norman Gottsmann
Phone: +49 6751 / 9303-140
Fax: +49 6751 / 9303-149
Accounts Receivable
Iris Schwenk
Phone: +49 6751 / 9303-125
Fax: +49 6751 / 9303-129
Accounts Payable
Christina Eich
Phone: +49 6751 / 9303-123
Fax: +49 6751 / 9303-129
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