Humidifier types

A fan pulling room air through a wet wick. The water leaves as vapour and the minerals stay behind in the wick, which is why it cannot make white dust and why the wick eventually goes stiff and white.

$60–$1,000 · up to 862 sq ft of real coverage · 15 of 15 cannot make white dust

A ceramic disc vibrating fast enough to throw water off its surface as a fog. Nearly silent, cheap to build, and the only mechanism that puts your tap water's minerals into the room as white dust unless something filters them out first.

$40–$350 · up to 296 sq ft of real coverage · 3 of 14 cannot make white dust

An ultrasonic with a heater in the water path, offering warm or cool mist from the same tank. The heat takes the chill off the mist and discourages what grows in a tank; it does nothing about minerals.

$80–$450 · up to 985 sq ft of real coverage · 5 of 9 cannot make white dust

Mounted on the ductwork and plumbed to a water line, so nobody ever fills it. Bypass units borrow the furnace blower and only run when the heat does; fan-powered units carry their own; steam units make their own heat and work with any system.

$180–$1,100 · up to 8,524 sq ft of real coverage · 6 of 6 cannot make white dust

The evaporative mechanism scaled up: gallons rather than litres, several wicks, and enough output to move the humidity in a whole floor. It is furniture, and it is the only portable class that competes with a whole-house install.

$150–$280 · up to 2,956 sq ft of real coverage · 5 of 5 cannot make white dust