Industrial furnaces with radiant heating are used for steel annealing at high temperatures. The heating elements of these furnace systems are arranged in such a way that a good temperature uniformity is ensured at working temperatures above 900 °C. In order to minimize the heat loss when opening hot, the height of the furnace chamber of these chamber-, bogie hearth- and top hat furnaces, as well as rotary hearth and continuous furnaces is lower than, for example, with convection furnaces. For heavy or large batches, for which heat treatment in a chamber furnace is out of the question, bogie hearth furnaces or top hat furnaces can be offered.