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World's First Set-Free Room Air Conditioner

Testing started with a cardboard model.
A room at the division director's home flooded with water during practical testing.

World's First Set-Free Room Air Conditioner

Around 100,000 small air conditioners were sold industrywide in 1965. By that time, TVs, refrigerators and washing machines had become ubiquitous, but although air conditioners were expected to become more widespread, they had yet to become popular. After an investigation as to why air conditioners were not adopted as quickly as other home appliances, the development team reached a conclusion that sales would increase if customers could install air conditioners by themselves where they wanted without having to pay for installation, and if they could remove the units when they were not necessary (air conditioners had only cooling functions at that time).

Development started from scratch. The members of the development team started with selection of the condensing heat exchanger, followed by choosing a hose to exhaust heat, a pump to circulate water and conducting a study on the ideal arrangement of components. The air conditioner was designed like a piece of furniture so that the whole unit would fit in aesthetically when it was installed in a room. The members also measured the sizes of doorsills, rails and carpets to make the product easy to move within the home. Members went from shop to shop, after work and on holidays, looking for suitable storage tanks, exhaust hoses, casters, and handles. A cardboard layout model was made to give shape to the designer's vision before building the first prototype.

In the summer of 1966, a practical test of the first prototype was conducted. The product had some flaws, and one room in the division director's home was flooded with water. The prototype had problems: it made a lot of noise, and had a faulty switch (designed to automatically stop the compressor when cooling water ran out). The members had to deal with a number of issues during the test, running around the house while doing so, yet they firmly believed that their air conditioner was worthy of being installed in Japanese homes in the years to come.

The next prototype was made at lower cost and the problems identified in the first test were overcome. The prototype was put through its second round of practical testing in the summer of 1967. A project team was organized to go over any design suggestions from testing. The team focused on finding ways to prevent substances in the water from accumulating in the water tank, surfaces of the copper piping and the water hose in the form of evaporation residue. They also conducted research on water deposit cleaners, and on the ideal construction that would make the air conditioners easier to clean.

On May 7, 1968, Toshiba started mass production of 500 units. Competitors were shocked by the news about this revolutionary air conditioner. Toshiba built 12,000 units in 1969 and more than 80,000 units in 1972. Toshiba was far ahead of other companies in this field for five consecutive years.

The company received the award for technological achievement (the advancement award) from the Japan Electrical Manufacturers' Association for its water-cooled set-free air conditioners in April 1970. In March 1973, Toshiba started mass production of air-cooled set-free air conditioners, which overcame the shortcomings of the previous water-cooled unit, e.g. water supply and deposit accumulation. Toshiba again received the technological achievement award from the Japan Electrical Manufacturers' Association in April 1974 for their new air-cooled version of the set-free air conditioner.

Construction manual for Set-Free

Construction manual for Set-Free

Collection of Set-Free (Later model)

Collection of Set-Free (Later model)

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