About us


DencoHappel (formerly GEA Air Treatment) is one of the leading technology innovators in the field of air treatment, air conditioning, and filter technology as well as cooling process air.

With its premium brands CAIRplus®, DENCO®, MultiMAXX®; Multi Flair®,
DencoHappel COM4®, Flex-Geko®, FireTex®, SepTex® and Sahara® as well as the DELBAG® products, DencoHappel has repeatedly set technological standards through innovation capability for over a century, and can satisfy nearly every conceivable customer wish.

DencoHappel with their headquarters are based in Herne, Germany. Production sites in Germany, Great Britain, Czech Republic, Turkey, China and India as well as own sales organizations and distributors in more than 50 countries guarantee customer proximity, high flexibility and efficiency.

We are a € 300 million business with over 1,700 employees. Together with its shareholder Triton Partners, the company invests in innovation and growth in all relevant markets and regions.


The origins of DencoHappel date back over a hundred years. The origins of today's DencoHappel date back to 1909. On the one hand, this is the year that Luftfilter-Baugesellschaft mit beschränkter Haftung (DELBAG®) was founded in Breslau. On the other hand, Otto Happel founded the "Gesellschaft für Entstaubungs-Anlagen mbH" (GEA) in Bochum in 1920, and in Great Britain, DENCO was founded in 1944, which was taken over in 2006.

Starting with the production of textile filters to filter the cooling air of electric machines, Otto Happel rapidly continued to develop the company. Already in 1922, he revolutionized the circulatory water cooling system of large electric machines by using the elliptical finned tube, which was also launched on the heating market after 1945.

The company grew continuously and was renamed "GEA Luftkühlergesellschaft mbH" in 1925. New manufacturing halls were built and the current production site in Herne was developed.

The next major step took place in 1954 with the founding of HAPPEL KG, in which the continuously expanded manufacture of convectors was consolidated.

In 1970 – fifty years after its founding – the current DencoHappel could refer to 8,000 air-cooled installations in process engineering, and simultaneously the 500,000th unit heater left the plant.

The breathtakingly fast growth of the company demanded new business structures. In order to finance the influx of capital, GEA AG was gradually transformed and went public in 1989.

The takeover of DELBAG Luftfilter GmbH, Berlin in 1990 completed the entry into air-filtration technology.

In 1995 – the 75th year of its existence – after further acquisitions with over 17,000 employees and more than 4 billion DM in sales, GEA had risen from being a components manufacturer to become a worldwide systems supplier. In 1999 Dr. Otto Happel, who at the time held the majority of GEA common stocks, sold his shares to Metallgesellschaft AG, which was renamed "mg technologies ag" in 2000, and initially he remained one of its major stockholders.
With the merger of "Gesellschaft für Entstaubungs-Anlagen“ (GEA) with "mg technologies" in 2005, the company was renamed GEA Group AG.

The expansion continued at the same pace: the British company DENCO of Hereford, a specialist for close-control and comfort air-conditioning systems for industrial and commercial applications, and the Turkish air treatment technology specialist ISISAN of Istanbul were taken over in 2006. The number of production plants for air-treatment technology rose to nine. In addition, access was gained to new regional markets and applications such as precision climate control of computer and telecommunication centers in Europe.

During the course of the strategic realignment of the GEA Group, the European holding company Triton took over the entire heat exchanger business in 2014. The GEA HX Management and Triton reorganized the previous HX business area into three operatively independent segments: Air Treatment (DencoHappel), Heat Exchanger Systems and Power Cooling Solutions.

The air-treatment segment has now been doing business under the name "DencoHappel" since mid-2015, and hence closes the circle to the two major product lines DENCO® and Happel® with their over century-old history, filling both prestigious brands with new life.

Value Proposition


Happel® stands for central and decentralized solutions in air conditioning. Happel® air conditioners are the guarantee for economical and environmentally-friendly air processing. The possible applications are very diverse, and comprise a broad performance range. Happel® covers filtering, heating and cooling, as well humidifying and dehumidifying air.


Since 1944, DENCO® stands for special solutions for controlling air quality, humidity and temperature in sensitive areas. The precision close-control units ensure exact and constant room-air conditions, such as are necessary, for example, in computing centers, server rooms or in hospitals and clean rooms.


DELBAG® is one of the best-known brands worldwide for air filtration. The outstanding technical expertise of the company is based on knowledge gained from its own research and development. Numerous milestones in air filtration, current patents, and results from laboratory experiments as well as continuous new developments confirm the high technological level of DELBAG® products.


Is it possible to heat a glazed building on its north side and cool it on its south side with a single system? Can an air-treatment system used in pharmaceutical or electronic settings equally be able to heat, cool, humidify, dehumidify, and also provide protection from microbes and irritating foreign particles?

These are tasks that our air-treatment systems perform every day around the world, with high customer satisfaction. Our broad range of offers for central and decentralized air handling systems provides a multitude of possible solutions in which the products as well as the measuring, controlling and regulation devices are all precisely adapted to the respective project and the working environment. With this individualization and thanks to our own in-house developments, we can respond with a system exactly suited to the respectively existing infrastructure, special requirements, and character of the building in question. The result is more efficiency and sustainability.

Corporate Social Responsibility

As systems supplier we work particularly sustainably and efficiently, right from day 1 of the project start. Thanks to our comprehensive program of air-handling systems, planners, systems contractors and architects can get complete solutions all from one source.

As a result, apart from plenty of leeway for customized design, the company offers further clear advantages: The products harmonize perfectly with each other to provide the desired specific climate with greatest efficiency and cost effectiveness. This saves time, energy and costs. Moreover, expensive and complex compatibility problems in adapting the units to the building management system are avoided right from the start.


One of numerous examples of how we understand and can implement sustainability in our products is the Villa Flora, which was built at the occasion of the World Horticultural Fair Floriade in Venlo in 2012. The building concept from the Dutch architect office Kristinsson demonstrates that sustainable construction as well as bringing together humans and plants has great potential for the urban development of tomorrow, and can simultaneously be realized in an environmentally-friendly manner.

The building ensemble consists of a huge greenhouse with exhibition space flanked by a docked office building. Despite the transparent glass architecture, the operation of the building was intended to be climate-neutral, effective and economical.

CAIR® air-handling units are responsible for the hygienic exchange of air. The air supply to the office rooms is provided by floor vents installed in double floors, which serve both as floor heaters as well as for cooling by means of displacement ventilation. Latent heat accumulators (PCM / Phase Change Materials) ensure an internal balance of temperature in the air-handling units.

The highly-publicized project is not only CO2 neutral, but its production of heat also suffices to cover the heating demand of the neighboring building as well.

Cradle to Cradle

The ecologically sustainable cradle-to-cradle system is likewise demonstrated in the Villa Flora. It consists predominately of glass, steel, concrete and wood, and is built in such a modular design that the durable elements can be easily recycled for other building purposes after being removed. DencoHappel products are conceived and marketed according to the same principle – cradle to cradle.

Ethics and employment

Sustainable actions already begin in the corporate culture and in the way employees are treated – in other words, in the company itself.
DencoHappel is a medium-sized company. We make use of these advantages by living and promoting the principle of personal responsibility. We call this the "entrepreneurial spirit". Such a spirit involves everyone acting as if they were owners and hence responsible for the resources and tasks at their disposal.
We live speed, since by using short paths in our work we can react and make decisions rapidly, flexibly and transparently. We place great value on a respectful and trustful cooperation with each other in the company as well as with our external partners.
Continuous change and the constant quest for improvement accompany everything we do. We simply call this: motivation to perform.
These values are our backbone. They are based on the experience and over 100 years of innovation capability as well as the technology leadership of DencoHappel.

© 2017 DencoHappel. All rights reserved.