Furnace A device in which heat is generated by burning a fuel. The heat may be used to process something, such as refining an ore, or for heating air for comfort.Related Articles: Glossary: Forced Air HeatingRadiant Floor Heating - Plain, Simple and LuxuriousNow is the Time to Reflect on what Radiant Heat can do for YouDream Big with In-Floor Radiant HeatSpring Unsprung with Radiant In-Floor Heating