Kang bed-stove

The kang (Chinese: 炕; pinyin: kàng; Manchu: nahan, Kazakh: кән) is a traditional heated platform, 2 metres or more long, used for general living, working, entertaining and sleeping in the northern part of China, where the winter climate is cold. It is made of bricks or other forms of fired clay and more recently of concrete in some locations. The word kang means "to dry".

Its interior cavity, leading to an often-convoluted flue system, channels the hot exhaust from a firewood/coal fireplace, usually the cooking fire from an adjacent room that serves as a kitchen, sometimes from a stove set below floor level. This allows a longer contact time between the exhaust (which still contains much heat from the combustion source) and (indirectly) the inside of the room, hence more heat transfer/recycling back into the room, effectively making it a ducted heating system similar to the Roman hypocaust. A separate stove may be used to control the amount of smoke circulating through the kang, maintaining comfort in warmer weather. Typically, a kang occupies one-third to one half of the floor space, and is used for sleeping at night and for other activities during the day.^[1] A kang which covers the entire floor is called a dikang (Chinese: 地炕; pinyin: dì kàng; lit. 'ground kang').^[1]

Like the European masonry stove, a massive block of masonry is used to retain heat. While it might take several hours of heating to reach the desired surface temperature, a properly designed bed raised to sufficient temperature should remain warm throughout the night without the need to maintain a fire.