Caliduct

Caliducts were a kind of pipes, or canals, placed along the walls of houses and apartments, used by the ancients for the conveyance of heat to several remote parts of the house, from one common furnace.

 This article incorporates text from a publication now in the public domain: Chambers, Ephraim, ed. (1728). "". Cyclopædia, or an Universal Dictionary of Arts and Sciences (first ed.). James and John Knapton, et al.