Definition (Source: Wikipedia)
***In American English, the term furnace on its own is generally used to describe household heating systems based on a central furnace (known either as a boiler or a heater in British English), and sometimes as a synonym for kiln, a device used to fire clay to produce ceramics. In British English the term furnace is used exclusively to mean industrial furnaces which are used for many things, such as the extraction of metal from ore (smelting) or in oil refineries and other chemical plants, for example as the heat source for fractional distillation columns.
The term furnace can also refer to a direct fired heater, used in boiler applications in chemical industries or for providing heat to chemical reactions for processes like cracking, and is part of the standard English names for many metallurgical furnaces worldwide.
Unique furnaces are used to run fire tests to qualify fire protection products for use in construction.
The heat energy to fuel a furnace may be supplied directly by combustion of some fuel, or electric furnaces such as the electric arc furnace or induction furnace use remotely generated electric power.