Notes on The Ondol

The following images were taken by Davey Clark.

There aren't very many traditional Ondols left in Korea from what I saw, although modern Ondols, with hot water pipes or electrical baseboards set under the floor are ubiquitous, in fact are the only heating systems I saw in Korea at all. This particular traditional Ondol was found in Jeolla province, in the south of the country, and that entire small cottage was built by a Korean man with an enthusiasm for the past. His actual house, which was right beside this small cottage, was modern.” DC.

Ondol is a relatively modern name, for the sub floor masonry heating system used throughout the Korean peninsula and parts of Manchuria.
Guduel is the traditional term used in Korean literature and is probably derived from the words guun dol which mean hot stone.

The Ondol closely resembles the Roman Hypercaust, (from Greek: below – heat) and its contemporary Iberian version: the Gloria. See Glorias Castillanas
The Ondol consists of a fire box, located in a cooking pit in the kitchen floor, with an extended horizontal smoke path running, beneath masonry floors, the full length of the dwelling, to a remote exterior chimney located at the opposite end of the building.

There is evidence from the Bronze age Unggi Hamgyeongbuk-do archaeological site in North Korea that proves that the Ondol has a history of at least 3 millenia. This makes it considerably earlier than the hypocaust, which is thought to have been invented by the hydraulic engineer Sergius Orata c. 95 BC, though this cannot be confirmed.

All images have an HD option. Click on image.

The dwelling has a rectangular foot print. The fire box of the Ondol is located in the fire pit of the kitchen at left. The sub floor flue system runs to the right below the other rooms of the building, before joining its chimney, of the rear right corner (out of view).

The fire pit in the centre of the kitchen floor, beyond the open doors.

The fire pit and location of the Ondols fire box within it. Unlike the hypercaust and Gloria, which are used solely for heating, having their fire boxes outside the building, the Ondol is used also for cooking, which necessitates having the fire box in the kitchen.

Detail of the cast iron cooking pot which is fixed in place.

View into the fire box, showing its stone lintel, and the narrow throat (top rear) and the capping stones of the flue way beyond the throat (obscure in this image).

Detail of the back of the fire box showing, again not very clearly, the throat and the start of the flue system and its capping stones.

The floor under which runs the Ondols smoke path. The flue is capped by large flat stones resting upon masonry pillars. The capping stones are covered by a bed of compressed earth with a high percentage of clay. The floor is protected by sheets of waxed paper.

The chimney is located just off the rear wall at the far end of the dwelling, opposite the kitchen.

Though the fire box is sunk below grade, the smoke path is built above grade and the floor of the dwelling actually raised to accommodate it. By contrast, the fire box and entire smoke path of the Gloria are just below grade.

The wooden chimney stack is made from 4 wooden planks. An electrical extraction fan is used to establish, or maintain, a draw, keeping the kitchen free from smoke.
Traditionally due to the length of the smoke path and short chimney, the kitchen would have been quite smokey.

The smoke path and connection to the wooden chimney.

The Ondol could be fired continuously or intermittently depending upon the weather or cooking needs. The fuel used was dry biomass, general agricultural waste, especially rice stems, and on special occasions wood.

See also: Viviendas Ondol (Espagnol)

Marcus Flynn


Articles by Marcus Flynn

Contact Pyromasse