3^rd and 4^th Century BC

The first predecessors of central heating systems, the so-called hypocauste heaters come into existence. The roots of these systems can be lead back to public facilities, mainly bath houses. These thermal baths were far distributed among the Roman and Hellenistic empires. In Rome alone, there were in the 4^th century AD next to 11 large thermal bath houses and more than 850 public baths. But also gymnasiums, hostels, smaller palaces, mansions and fortresses were supplied with central heat. Aside from the Romans and almost at the same time, the Chinese developed the so-called Kang-Heater, a relatively similar form of this central heating system. Already at this point in time, there existed regular trade between the Chinese and Roman empires, which seems to give prove to the thesis of technology-transfer at this early stage between the two empires. Because of the downfall of the Roman empire in the 3^rd and 4^th century AD, these developments became forgotten.