The AGA cooker is a heat storage stove and cooker, which works on the principle that a heavy frame made from cast iron components can absorb heat from a relatively low-intensity but continuously-burning source, and the accumulated heat can then be used when needed for cooking. Originally heated by slow-burning coal, the Aga cooker was invented in 1922 by the Nobel Prize-winning Swedish physicist Gustaf Dalén (1869–1937), who was employed first as the chief engineer of the Swedish AGA company (Swedish: Aktiebolaget Svenska Gasaccumolator, English: Joint stock company Swedish Gas Accumulator). The cookers were first imported to Britain in 1929, and were first manufactured there under licence in the early 1930s. The cast iron components were first cast at the Coalbrookdale foundry in the 1940s, where they are still made today by the Aga Rangemaster Group.
Gustaf Dalen lost his sight in an explosion while developing his earlier invention, a porous substrate for storing gases, Agamassan. Forced to stay at home, Dalen discovered that his wife was exhausted by cooking. Although blind, he set out to develop a new stove that was capable of a range of culinary techniques and easy to use.
Adopting the principle of heat storage, he combined a heat source, two large hotplates and two ovens into one unit: the AGA Cooker. The cooker was introduced to England in 1929, and its popularity in certain parts of English society (owners of medium to large country houses) led to the coining of the term "AGA Saga" in the 1990s, referring to a genre of fiction set amongst stereotypical upper-middle-class society.
Aga cookers can also make a contribution to space heating, although it is not true that they can heat an entire house, despite persistent claims to the contrary, presumably arising because the cookers look similar to the many types of central-heating range such as the 'Stanley' or the 'Rayburn' Range, also made by the AGA Rangemaster Group.
Since 2006, the slump in demand for the cooker has led to severe stock market falls for the company, crashing 25% in one day in November 2008 when the company announced disappointing sales figures across the range. Profits in 2008 were £14.4m but had reduced by 97% to £500,000 in 2009.
AGAs have recently been criticised for their high energy consumption and inefficiency. A small, two-oven AGA running on gas will use approximately 425 kWh per week (22,100 kWh per year; perhaps half that if switched off during the summer months). The average standard gas oven and hob uses 580 kWh during a year, only 2.62% of the AGA's consumption.
AGA's own figures for expected energy consumption for their two-oven AGA support this criticism, suggesting a weekly consumption of 40 litres of kerosene or diesel, 60 litres of propane gas, 425 kWh of natural gas or 220 kWh for the electric models. This would indicate that the smallest two-oven gas AGA providing simple cooking functions (i.e. no water heating or central heating) consumes almost as much gas in a week as a standard gas oven/hob does in nine months.
AGA has provided an analysis of their own, which claims that they have taken steps to reduce energy consumption.
While much has been made of the AGA's energy consumption, owners often talk about how they believe the AGA actually makes their homes more energy efficient, as the AGA does a number of jobs, such as replacing several radiators, and is not simply a cooker. They also use the fact that it is made from recycled materials and claimed to last for at least half a century to back this up.
The vast majority of AGAs sold today are programmable and AGA announced an upgrade initiative in 2009, meaning that owners of older AGA cookers can have them modified so they are programmable. The latest model the AGA Total Control  uses the same radiant heat to cook (without drying the food out), but is designed to be switched off like a regular cooker when not in use, using far less energy as a result.
Three main models of AGA are currently in production: two-, three- and four-oven versions, with the four-oven version wider than the others. The two-oven model has three doors behind which are the burner, roasting oven and simmering oven. The newer three-oven model also includes a baking oven, and the four-oven version also has a warming oven and warming plate on the top. All models have two hotplates — a boiling plate and a simmering plate. The cookers come in a range of different colours, but the most popular is the original cream and, more recently, black.
The AGA is known for its longevity, with many cookers still operating after more than 50 years. In 2009, in conjunction with the Daily Telegraph and to celebrate the 80th anniversary of its founding, AGA set up a competition to find the oldest AGA still in use. There were thousands of entries, but the winning cooker was installed in 1932 and belonged to the Hett family from Sussex. This cooker is now installed in the reception area of the company's Coalbrookdale foundry. Authorised renovated models of all types are available from Aga's only renovators Aga Twyford.
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