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Electric dryers The electric dryer generally uses a coiled wire that is heated with electric current. The amount of electric current is varied to adjust the air temperature. In the United States, electric dryers typically have a 4-wire NEMA 14-30 plug, rather than the 3-wire NEMA 5-15 plug used by most appliances, and need a 30-ampere, 240-volt centertapped single-phase circuit. Gas dryers The gas dryer employs a gas burner that burns natural gas, propane, or butane to form a jet of hot gases that are directed into a venturi chamber, which uses Bernoulli's principle to pull in ambient air and raise its temperature. The air temperature can be altered by adjusting the size of the gas flame or, more commonly, by merely extinguishing it and relighting it. Condenser dryers Condenser dryers are ventless and are usually electric. A heat pump works as a dehumidifier to extract moisture. Condenser dryers generally have smaller capacity and longer drying times than vented dryers, due to lower operating temperatures. Models exist which combine a washing machine and a dryer. (see also: heat exchanger) Spin dryers Spin dryers use centrifugal force to extract water from clothes. They extract more water in two minutes than a gas or electric drum dryer can in twenty, saving significant amounts of energy. However, they will not completely dry the clothes and must be used with a conventional dryer or clothesline. Static Clothes dryers can cause static cling, through the triboelectric effect. History Contrary to Internet rumors, the first tumble dryer was not invented by American George T. Sampson. A hand-cranked version was created in 1799 by a Frenchman named Pochon. Sampson's United States patent (number 476,416), which he received on June 7, 1892, was for an improved rack for holding wet clothes near a heat source. Electric tumble dryers appeared in the 20th century. Ecology Energy Star, a United States government program concerned with energy efficiency in consumer products, does not rate clothes dryers, because most of the clothes dryers marketed in the U.S. consume similar amounts of energy. | ||||||||||
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