There are two general classes of rotating dryers: electric and gas. Both of these refer to the method used to raise the temperature of the air flowing through the tumbler, since the tumbling action is usually electrically powered.

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 and other countries following USA wiring standards, 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. Small "portable" clothes dryers, popular with urban dwellers, normally use conventional 110 volt connections.

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. Gas dryers require electricity to spin the clothes, but the amount of electricity is much smaller than in an electric dryer removing the need for a special connection. The motors normally run on standard 110 volt electricity.