Direct steam-powered kettles use a tank of steam to heat liquids directly rather than through an electric element. Direct steam-powered kettles produce high-pressure steam, which transfers heat to the surrounding environment or through a heat exchanger. Direct steam kettles are referred to as ‘integral heaters’ as the generating and heating functions take place in one unit. They are the most traditional type of kettle and are used in breweries around the world. They are typically made of copper, stainless steel, or aluminum. The heating element is usually made of stainless steel or another high-quality metal. Most of these kettles are designed to be used with a certain heating element. The kettles may be compatible with natural gas, propane, or electricity, depending on the brand. The heat exchanger is made of stainless steel and has thousands of small holes on its surface. The holes are small enough to prevent the escape of steam. The heat exchanger is placed in the bottom of the kettle so that the ground underneath can be used as a heat sink.