Hypocaust

A hypocaust (Latin "hypocaustum") is an ancient Roman system of central heating. The word literally means "heat from below", from the Greek "hypo" meaning below or underneath, and "kaiein", to burn or light a fire. They are traditionally considered to have been invented by Sergius Orata, though this is not fully confirmed.

Operation

Hypocausts were used for heating public baths and private houses. The floor was raised above the ground by pillars, called pilae stacks, and spaces were left inside the walls so that hot air and smoke from the furnace ("praefurnium") would pass through these enclosed areas and out of flues in the roof, thereby heating but not polluting the interior of the room. Rooms requiring the most heat were placed closest to the furnace, whose heat could be increased by adding more wood. It was labour-intensive to run a hypocaust as it required constant attention to tend the fire, and expensive in fuel, so it was a feature of the villa and public baths.

Vitruvius describes their construction and operation in his work De Architectura in about 25 BC, adding details about how fuel could be conserved by designing the hot room or caldarium for men and women should be built next to one another, adjacent to the tepidarium so as to run the public baths efficiently. He also describes a device for adjusting the heat by a bronze ventilator in the domed ceiling.

The hypocaust is generally regarded as a major Roman invention which improved the hygiene and living conditions of citizens, and was a forerunner of modern central heating.

After the Romans

The hypocaust continued to be used in the Mediterranean region during late Antiquity and by the Umayyad caliphate, though Muslim engineers and inventors eventually replaced it with an improved central heating system where heat travels through underfloor pipes from the furnace room by the 12th century. [citation|last=Hugh N. Kennedy|title=From Polis To Madina: Urban Change In Late Antique And Early Islamic Syria|journal=Past & Present|publisher=Oxford University Press|year=1985|volume=106|issue=1|pages=3-27 [10-1] ]

A derivation of hypocaust, the "gloria", had been in use in Castile until the arrival of modern heating. After the fuel (mainly wood) has been reduced to ashes, the air intake is closed to keep hot air inside and slow combustion.

Korean traditional houses use an "Ondol" which is similar to a hypocaust, drawing smoke from a wood fire typically used for cooking.

ee also

*De Architectura
*Roman engineering
*Roman technology
*Ondol
*Gloria in the Spanish Wikipedia.
*Kachelofen in the German Wikipedia.
*Kang bed-stove
*Vitruvius

External links

* [http://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/SMIGRA*/Balneae.html About Roman baths] (referring to Sergius Orata), by William Smith.
* [http://links.jstor.org/sici?sici=0031-8299(199621)50%3A1%3C56%3ASOIOTH%3E2.0.CO%3B2-N Disputing the priority of Sergius Orata] Garrett G. Fagan's paper "Sergius Orata: Inventor of the Hypocaust?" published in Phoenix, Vol. 50, No. 1 (Spring, 1996), pp. 56-66
* [http://www.pages.drexel.edu/~khm24/AE_Design1/A5/hypo.htm Hypocaust heating] Wordreference.com
* [http://www.romans-in-britain.org.uk/inv_central_heating.htm Roman central heating: the hypocaust]
* [http://www.smr.herefordshire.gov.uk/roman/hypocaust.htm Diagram of a Roman hypocaust system]
* [http://www.pages.drexel.edu/~jpm55/AE390/A5/hypocaust.htm Hypocaust]
* [http://www.channel4.com/history/microsites/T/timeteam/2004_white_build.html How to build your own hypocaust] Channel 4 Time Team project

References

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