Hair dryers: how they work

In short: A hair dryer draws in air, warms it over a heating element and blows it out again with a fan. Warm, moving air makes the water in the hair evaporate much faster.

In more detail: Inside there is a small electric motor with a fan wheel and a heating wire, usually made of a nickel-chromium alloy. Temperature and airflow can be adjusted separately with switches.

In detail

• Fan: An electric motor drives a fan wheel that pulls air in through the intake at the back of the device and pushes it forwards.
• Heating element: The airflow passes over a coiled heating wire that heats up strongly because of its electrical resistance.
• Why it dries: Warm air can hold more water vapour, and the constant airflow carries the moist air straight away from the hair.
• Settings and cool shot: Several heat and fan settings allow gentle drying; the cool setting helps to set a hairstyle without adding more heat.
• Overheating protection: A thermostat or thermal fuse switches off the heating if the inside gets too hot, for example because the air intake is covered.
• Lint filter: The grille at the air intake collects dust and hair; if it is cleaned regularly from the outside, the airflow stays strong and the device does not overheat.
• Attachments: A narrow nozzle concentrates the airflow for targeted styling, while a diffuser spreads it out widely and gently, for example for curls.
• Safety in the bathroom: A hair dryer must never come into contact with water; unplug it after use, do not wrap the cable around the hot device, and never open a damaged device yourself, but replace it or have it repaired professionally (sicherung-und-fi-schalter-grundlagen, elektrischer-rasierer-funktionsweise).