1. How old Japanese homes warmed only the area around the fire, not the whole room
On a winter night, families gathered in the same place. In old Japanese homes, this was around the irori (a sunken hearth), beside the hibachi (a portable charcoal brazier), or inside the kotatsu (a heated table). According to university lecture materials, the hearth in pit-dwellings from the Jomon period is considered the prototype of the irori, and the kasha from the Nara period is said to be Japan's oldest hibachi. By the Muromachi period, the kotatsu and ankago (a portable charcoal heater) appeared, and fuel changed from firewood to charcoal, which produces less smoke [1]. These dates are rough estimates, and the exact order of small changes is not fixed.
The same materials explain that in Japan, instead of heating the entire room like in Western countries, a way of warming the area around the body developed. People got close to the fire to keep warm. So, when did tools that heat whole rooms arrive in Japan?
2. A European-style stove made in Hakodate in 1856
A record states that in 1856 (Ansei 3), something modeled on a "Kacheru" (a European-style freestanding fireplace) was made in Hakodate. The Encyclopedia Nipponica considers this the first domestically made stove [2]. From the Meiji to Taisho eras, foreign-made stoves were imported one after another, and many imitations were made domestically. Oil stoves were also used from the Meiji period, but they seem to have been treated as luxury goods at first [2]. At that time, another heating method was arriving: the electric heater.
3. Why electric heaters were out of reach for ordinary people
Electric heaters were imported around the end of the Meiji period, and domestic products were made by the beginning of the Taisho era. The start of sales for domestic electric heaters and irons is said to be 1915 (Taisho 4). However, this is an estimate for sales, not necessarily the exact date of the very first unit [3]. Yet, at that time, electric lights had only just become widespread, and electricity rates were extremely high, making these items out of reach for ordinary people, according to the encyclopedia [2].
Some numbers help here. According to materials from the Osaka City Science Museum, in the fiscal year 1932, statistics from the Osaka City Electric Bureau showed about 510,000 electricity customers used electric lights, while about 50,000 used electric heat. Dividing 50,000 by 510,000 gives about 0.1, meaning electric heat users were roughly one-tenth of light users. Note that "electric heat" includes irons and other items, so this is not just the number of stoves. Around 1933, the central price of an electric iron was 2 to 6 yen, while fans and radios cost 25 to 40 yen [3]. Fans and radios cost several times to about 20 times as much as electric irons. The source gives no price for electric heaters themselves. The Edo-Tokyo Museum holds American-made (THERMA brand) electric heaters from the Taisho to early Showa periods, and Showa-era Shibaura Seisaku-sho electric heaters [5]. Physical examples do exist.
4. How the alloy Nichrome made the glowing wire in electric heaters possible
When you look inside an electric heater, you see a glowing red wire. This is called a heating element, a wire that gets hot when electricity flows through it. A representative material used for heating elements is Nichrome, an alloy of nickel and chromium. Albert Marsh took out a patent (No. 811,859) in the United States in 1906. English Wikipedia explains that high-resistance wire can be used as a strong and safe heating element, and it was used in home appliances like toasters [4]. A wire that does not break easily even when glowing red helped in making tools that turn electricity into heat. However, it cannot be said that all heating elements in Japanese electric heaters were Nichrome, and when it started being used in Japan is not mentioned in these materials.
5. How heating the whole room spread to homes after World War II
After World War II, life became more Western-style, and building insulation and airtightness improved. Lecture materials summarize that along with these changes, stoves and fireplaces that heat the whole room spread, replacing the hibachi [1]. Regarding oil stoves, the encyclopedia explains that after oil controls ended after the war, high-power models became widely used [2]. In 1978, Mitsubishi Electric released the "oil gasification fan heater." This is recorded in the company's history, and some reports call it the world's first home-use oil fan heater [6]. In addition to tools that warm the area around the fire, the heat source for warming rooms also widened to oil.
6. How to find the heat source of the heaters in your home
What you can do today: Look at the main body or instruction manual of heating devices in your home or school without turning them on. They state what powers the heater, such as "electricity," "kerosene," or "gas." For devices that use fire, always look with an adult at home.
What you can look up online: Search for "electric heater" in the Edo-Tokyo Museum's digital archive to see photos and descriptions of real items from the Taisho to early Showa periods [5].
Official information: You can check timelines and statistics in Mitsubishi Electric's official history [6] or the Osaka City Science Museum's "Monthly Universe" August 2022 issue [3].