Furnace and method for treating material

A furnace for the treatment of material, the furnace comprising:

• a) a housing with a housing interior space, wherein the housing is gas-tight apart from passage regions for fibers;
• b) a process space, which is situated in the housing interior space of the housing;
• c) an atmosphere device configured to generate a hot working atmosphere and which comprises a flow system with flow ducts that form flow passages, wherein the flow ducts are arranged in the housing interior space and wherein each flow duct delimits one flow space, with the result that the respective flow spaces are connected in flow communication to the process space in such a way that the hot working atmosphere can be fed to the process space with at least one main flow direction and can be discharged from the process space;
• and
• d) an overhaul system, by way of which the flow spaces of the flow ducts are accessible through the housing, wherein the overhaul system includes at least one overhaul entrance, at least one covering plate that is configured to selectively cover the at least one overhaul entrance and an overhaul door that is configured to selectively cover the at least one covering plate.