reverberatory furnace

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A furnace or kiln in which radiant heat from the burning fuel is reflected downward from the roof onto the material under treatment.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A form of kiln, used in smelting and refining, in which the material is melted by the reflected heat of an overhead flame

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a furnace in which the material that is being treated is heated indirectly by flames that are directed at the roof and walls of the furnace