1 1 century, two different stoves, sauna and cooking, were built side by side, and the kitchen and bathroom were integrated, so cooking and sauna were not delayed [1-2]. At the end of 18, "embedded" brick sauna equipment appeared, which has two or three separate parts. The bottom layer is used to burn firewood, the middle layer is paved with pebbles, and the top layer is a flue with a regulating valve, which leads to the roof and connects with the chimney. At that time, most buildings were wooden structures, and this kind of "embedded" equipment reduced the occurrence of fires, which was once popular in 19 century [1-2].
At the beginning of the 20th century, Finnish factories began to mass-produce metal sauna equipment, and a new sauna equipment industry was formed. The hearth of this sauna equipment is an independent chamber, and it still retains the flue. Unlike before, the flame and water do not directly contact the stone, so long as the wood is burning, the stone can be continuously heated [1-2].
Traditional sauna equipment is heated by burning firewood, which has obvious farming color. With the development of urbanization, this feature is incompatible with the modern lifestyle. So in the 1930s, the sauna equipment driven by electricity came out. Thanks to the progress of science and technology, sauna equipment is constantly updated. Safety and convenience make sauna penetrate into Finnish life in an unprecedented depth and breadth. In addition to sauna equipment in public and private homes, large companies and institutions in this country have equipped their employees with sauna equipment, and even the president's office has set up special sauna equipment. Now, most newly-built aristocratic houses and hotel rooms are equipped with a "mini" sauna equipment next to the bathroom.
After the appearance of classical sauna in ancient Rome, the neighboring Nordic people did not sweat all the year round because of the cold climate, so in order to try to sweat, they accepted a sweaty sauna, and on this basis, they constantly improved sauna equipment and bathing methods, especially with the development of science and technology, the Nordic people applied advanced technology to sauna equipment, thus making the sauna reach the modern level. Sauna equipment can be divided into dry type and wet type from bathroom environment and sweating mode.
Sauna equipment was first introduced to China from northern Europe. Dry sauna spread from Finland to China, so it is called Finnish bath, and wet sauna spread from Turkey to China, so it is also called Turkish bath.