flue vs furnace

flue

noun
  • A pipe or duct that carries gaseous combustion products away from the point of combustion (such as a furnace). 

  • In an organ flue pipe, the opening between the lower lip and the languet. 

  • An enclosed passageway in which to direct air or other gaseous current along. 

furnace

noun
  • An industrial heating device, e.g. for smelting metal or baking ceramics. 

  • A place or time of punishment, affliction, or great trial; severe experience or discipline. 

  • Any area that is excessively hot. 

  • A device that provides heat for a building; a space heater. 

verb
  • To heat in a furnace. 

  • To exhale like a furnace. 

How often have the words flue and furnace occurred in a corpus of books? (source: Google Ngram Viewer )