What type of humidifier is known to leave fine white dust in the ductwork?

An atomizing humidifier is known for producing very fine water droplets that can be easily distributed into the air. When these tiny droplets evaporate, they can leave behind minerals and impurities contained in the water, which often manifest as a fine white dust. This dust accumulates in the ductwork and on surfaces throughout the area where the humidified air circulates.

In contrast, other humidifier types either work by different mechanisms or do not produce this particular dust. An evaporative humidifier uses a wick to absorb water, allowing it to evaporate into the air without creating residue. A steam humidifier boils water to create steam, which is then cooled slightly before being released, minimizing the chance of leaving dust in the ducts. Ultrasonic humidifiers produce a cool mist using ultrasonic vibrations, and while they may also cause some deposition, they typically do not produce the same noticeable dust as an atomizing humidifier when using hard water.