The central heating system was invented by the Romans. It was first used in northern Rome in 100 A.D. Air which was heated in furnaces was led through empty spaces which were made under the floor. This air was let out through pipes in the walls. This system was known as hypocaust. Central heating worked because hot air travelled through spaces and gaps created under the floor and on the walls. This space was created by constructing a floor on top of a mass of tiles or stones. The walls constructed in between these rooms were two small walls which had small gaps between them. The hot air was transmitted from a furnace to these gaps. It was the job of the slaves to see that the furnaces were well stocked up to keep the central heating system working.
