Black Friday 2026: the humidifiers worth watching

A furnace humidifier, also called a whole-house humidifier, is mounted on the ductwork of a forced-air system and humidifies every room; it connects to a water line and is usually installed by an HVAC technician. The models here are portable: they plug in and humidify one room, which is often enough for a bedroom or a living room, and they work with any heating system, baseboard heaters included.

Measure with a hygrometer: many smart humidifiers have one built in and hold the level you set. If the reading stays low and you notice static shocks or a dry throat, a humidifier can help. On very cold days, watch your windows: if condensation or frost forms on the inside, the air is already too humid for the weather, so turn the setting down, because that moisture can lead to mould.

Empty and refill the tank every day rather than topping it up, and descale it once a week with diluted white vinegar or citric acid, then rinse well. A top-fill tank, like the one on the Levoit Classic 300S, is easier to reach into and wipe out. With hard tap water, an ultrasonic model can leave white dust on furniture; distilled water prevents it. On models that also purify, check the manual for when to clean or replace the filters.