Hypocaust

from Wikipedia, the free encyclopedia

A hypocaust or hypocausts ( Latin hypocaustum , Greek. Ὑποκαίειν hypokaíein "light including burn including", of which: ὑπόκαυστος, -ον hypókaustos, -one "from below (ὑπό-) burnt / heated (καυστός)") is a hot air heating (hypocaust ) , in which a solid body is flowed through with warm air, but which has a lower surface temperature than a radiator . Floors or walls are mainly used as solid heat transfer media, but also solid benches or other components.

This form of hot air heating comes from Roman antiquity and was initially only used in thermal baths , later generally in Roman houses.

Ancient construction

Model of a Roman bathhouse ( thermal bath ) with underfloor heating . On the left of the picture is the actual bath house, on the right of the picture the attached boiler room. The floor has been partially cut open for better visibility ( Saalburg Roman fort ).

The construction consists of a furnace ( Latin praefurnium ), a boiler room (Latin hypocaustum ) below the floor and fume cupboards for the hot air and exhaust gases. The kiln was mostly outdoors. The area of ​​the underfloor heating ( suspensura ) , which was supplied with warm or hot air, consisted of 30 to 60 cm high brick or stone towers, which were stacked at a distance of about 30 to 40 cm and initially carried a larger cover plate. The large supporting plate on which the screed was applied lay on this plate . The entire construction of the floor was about 10 to 12 cm thick and took at least several hours, if not a day or two, to warm up completely. From the boiler room located under the heated room, the hot air flowed into the wall ducts ( tubuli ), which in this way also heated the walls. Only then did the air escape into the open ( tubulature wall heating ). The Roman Gaius Sergius Orata (around 90 BC) is considered an inventor in antiquity.

Hypocausts had an extremely high energy consumption, so that archaeologists today assume that during the later Roman settlement in the vicinity of settlements, the forests were cut down because they were used as fuel.

Roman canal heating is a further development for buildings with a relatively low heat requirement .

There is a reconstruction, for example, in the Reiss-Engelhorn-Museums in Mannheim, but also in almost every museum of Roman provincial legacies.

Modern construction

Sketch of a modern house with solar hypocaust heating

Nowadays, hypocaust heating is still the same principle. The air is not always through an oven, but also through solar energy, z. B. air collectors , heated. Modern hypocausts, for example, are concreted in ceilings as pipes or built directly as sand-lime brick walls.

Hypocausts are used as an alternative heating, they have a larger surface area than a floor-standing radiator, so they need a lower surface temperature (around 30 degrees Celsius) for the same room temperature, which creates less convection. This calmer warm climate is perceived as more pleasant and does not dry out the room air as much.

Korean ondol heating has always been a hypocaust-like type of underfloor heating.

In winter gardens , a so-called “hypo-exchanger” system is sometimes used, with which overheating or draft problems can be avoided. In the warm air in the winter garden, water (irrigation water or fountain water) evaporates, the moist air that rises is sucked off at the highest point of the winter garden and passed through hypocaust pipes on the colder ground. There the water vapor condenses and the released heat of condensation is given off to the ground. The low-moisture, but not necessarily cold air is then fed back into the winter garden in order to cool down the winter garden in the cycle.

literature

  • Gustav Fusch : About hypocaust heating systems and medieval heating systems , at the same time dissertation 1910 at the Technical University of Hanover, Hanover: Gebrüder Jänecke, 1910
  • Fritz Kretzschmer: Hypocausts . In: Saalburg Jahrbuch 12, 1953, pp. 8–41.
  • Heinz-Otto Lamprecht: heating. In: The New Pauly (DNP). Volume 5, Metzler, Stuttgart 1998, ISBN 3-476-01475-4 , Sp. 258-261.
  • Hans Christian Grassmann: The function of hypocausts and tubules in ancient Roman buildings, especially in thermal baths. Explanations and calculations . Archaeopress, Oxford 2011, ISBN 978-1-4073-0892-0 . - Review in Sehepunkte 14, 2014, No. 3 .
  • Hannes Lehar: The Roman hypocaust heating. Calculations and considerations on performance, structure and function . Shaker, Aachen 2012, ISBN 978-3-8440-0796-1 ( excerpt ).

Web links

Commons : Hypocaust  - collection of images, videos and audio files