In 1917, Johann Viessmann opened his small independent locksmith in the city of Hof an der Saale and so started a great development process. Today the Viessmann Group is one of the leading international manufacturers of heating, refrigeration and air-conditioning systems. The new cleanroom product line was conceptualised in 2003 and is today successfully marketed and developed by Viessmann Technologies GmbH from its Hof headquarters. A team of international experts is in charge of ambitious projects throughout the world.