Our history

From a single fiery entrepreneur to a solid market leader

1966

Willy Callens founds Callens.

Willy Callens started a one-man business in residential heating with the ambition to serve customers faster and better. Willy built his company in Hulste, West Flanders, on values that still form the backbone of the Callens Group today: take good care of your people, exceed your customers’ expectations, and set the bar so high that excelling becomes the norm.

1977

Shift from residential to industrial customers.

Willy never shied away from taking bold chances. He made the shift from the residential to the industrial market, where the need for good engineers and installers was high. He soon hired his first engineers and, together with the whole team, evolved toward total projects for industry: design, installation, and service.

1987

Move into a new and larger location in Harelbeke.

The shift to industry brought a lot of work, causing the team to grow. Willy purchased a completely new site in nearby Harelbeke, with more offices and a larger workshop.

Willy was the commercial and operational leader. His wife, Lena, meanwhile blossomed into bookkeeper, warehouse manager, HR manager, buyer, and project leader.

2001

Acquisition of steam boiler manufacturer EMK.

Callens’ first strategic acquisition was that of steam boiler manufacturer EMK from Wetteren. With it, we brought extra expertise in-house. In 2003, we fully integrated EMK into our operations, and until the end of 2018 we went to market together as ‘Callens & EMK.’ A name that still stirs warm memories for many people in West and East Flanders.

At the end of 2018, we made the deliberate choice to once again build on our family identity. Since then, we have continued as ‘Callens,’ a name that both honors our roots and gives direction to our future.

2007

Air Technology division strengthens end-to-end support.

With the arrival of our Air Technology division, we significantly expanded our services. From then on, we have been supporting customers not only with their production heat, but also with their entire industrial HVAC. This way, we offer one integrated solution and greater peace of mind.

2008

Waregem becomes the definitive home base.

Callens shines along the E17 in Waregem with a brand-new site to support past and future growth. It is a unique base of operations with spacious offices, a workshop, and a large boiler warehouse.

2010

Founding of the Callens-Vyncke joint venture.

Callens-Vyncke came about by combining the strengths of the family businesses Callens and Vyncke. In a short space of time, the company blossomed into a leading integrator of gas turbines and engines, with a focus on combined heat and power. In 2025, the joint venture came fully under the wings of Callens. After all, the energy transition kept bringing the core activities ever closer together.

2016

Regional expansion in Geel.

We made our mark in the Kempen region with an office building and adjoining workshop in Geel. From there, we offer local expertise and fast service. That combination is clearly appreciated, because, in just over five years, revenue there rose by 524%. At the end of 2026, this location will move to nearby Laakdal, where a large new building is planned.

2018

Optimum joins the Callens family.

Optimum – founded in 2000 in the Netherlands – adds thermal afterburning and heat recovery technology to the Callens portfolio. Once again, a strategic move toward further end-to-end support for industrial customers. On top of that, the company is a seedbed for new technologies, such as hydrogen boilers and MVR, tailored to industry.

2021

Expansion on all fronts.

Foothold in Liège.

Callens’ third location opens in Liège. A completely new team now offers a local service and expands the possibilities for total projects. After barely five years, revenue there rose by 270%. We decided to invest in our own building there as well and, at the end of 2026, we will move to a brand-new site just 500 m away.

The Waregem home base expands.

Callens keeps growing. In Waregem, the office space doubles and we invest extra in experience, with the Calliër Cafee as the beating heart for employees.

Panoramix opens its doors to the public.

The newest building in Waregem holds a hidden gem: Panoramix by Callens, a light-filled party and event hall. Before long, we opened the space to a broad, entrepreneurial public and now host up to 80 events a year.

2025

Acquisition of Jonker in the Netherlands.

Callens spreads its wings in the Netherlands with the acquisition of the renowned Ketelonderhoud Jonker, number 1 in service and maintenance of steam and hot water installations. The collaboration gives Jonker and the Callens Group the knowledge and clout to strengthen their leading position in the Netherlands and to further shape the industrial energy transition there, bolstered by everyone’s experience in technologically advanced techniques for total projects.

2026

Acquisition of Cometi in France.

The group welcomes the French company Cometi, a national top player in industrial heating techniques, into its international growth story. With this step, Callens establishes a local foothold in France to further roll out the energy transition there, drawing on proven expertise and a broad range of techniques.