Vicks
Vicks Cool Moisture V3900
Where the VUL545 atomises, this one evaporates - a wick, a fan and a UV lamp in the reservoir. For anyone who bought a Vicks ultrasonic and then found white powder on the dresser, the V3900 is the same brand's answer, and it is the cheaper half of the answer compared with Honeywell's HCM-350. A gallon a day against a 400 sq ft claim overstates by about 60%, which is mild by the standards of this category. The wick is the ongoing cost and the reason some owners drift back to filter-free units.
The room-size claim, reconciled
246 sq ft supported · box says 400 sq ft
The box says 400 sq ft. By the winter load calculation this output supports about 246 sq ft — the claim is 1.6× the room the machine can hold.
Holding 400 sq ft takes about 1.62 gal/day, which drains this 1-gallon tank in roughly 15 hr — against the 24 hours Vicks advertises, which is measured at the lowest setting.
What a year costs
Vicks WF2 wick filters run roughly $14 each, changed every one to two months in season. Electricity assumes the rated 40 W for 12 hours a day across a 150-day heating season at 16¢ per kilowatt-hour.
Specifications
A claim the maker makes
Vicks says UV light treats the water to kill up to 99.999% of bacteria, mould and viruses in the water. We quote it rather than repeat it: this site has not tested it and neither has anyone independent.
Maintenance profile
- Top fill
- No — tank comes off and goes to the sink
- Replaceable media
- Wick, replaced through the season
Facts, not a score. Which of these matter depends entirely on whether the unit ends up somewhere you will actually clean it.
Features
- Evaporative wick - no white dust
- UV lamp treating the reservoir water
- 1-gallon tank, 24-hour run
- VapoPad slot
- Two speeds
Pros
- Solves the white-dust problem that drives most returns of the brand's ultrasonic models
- Keeps the VapoPad slot, which is usually why someone is buying Vicks in the first place
- Cheaper than the equivalent Honeywell evaporative while doing the same job
Cons
- Wick filters at roughly $14 every month or two, which the sticker price does not hint at
- No humidistat, though an evaporative slows itself as the room fills in a way an ultrasonic cannot
- Audible fan - it is the mechanism, not a fault
- The UV claim covers the water in the tank, not the air in the room, and Vicks words it carefully
What owners say
No owner discussion collected for the Vicks Cool Moisture V3900 yet. The pros and cons above come from owner reports and the maker's documentation, and this section will fill in when there is enough first-hand material to summarise honestly. We would rather leave it empty than invent it — how we compare explains why.
Vicks Cool Moisture V3900, head to head
Looked at alongside it
More from Vicks →
Vicks declines to put a square-foot number on this one, describing it only as a medium-room unit - which, given how the rest of the category behaves, is its own kind of honesty. A 4.5-litre tank running 30 hours works out to just under a gallon a day, the same ballpark as everything else at this price. Dual scent-pad slots, a variable output dial, no filter. The usual ultrasonic caveats apply and the tank neck is narrow enough that cleaning it properly means a bottle brush.
234 sq ft supported
Vicks sells more humidifiers through drugstore shelves than most of this catalog sells anywhere, and the VUL545 is the one people pick up at nine in the evening when a child has croup. It works: a gallon of water, visible cool mist, a scent pad slot for menthol, and no filter to have forgotten to buy. What it will not do is hold 400 square feet - that room wants about 1.6 gallons a day, four times what the advertised 36-hour run delivers - and on hard water it powders dark surfaces within a few days.
165 sq ft supported · box says 400 sq ft
A boiler with a tank on it, and the oldest idea in the category. Steam humidifiers have no ultrasonic disc to scale, no wick to replace and no fan to hear - the water boils, minerals stay in the pot, and what leaves the machine is distilled by definition. That is why the V745A shows up in so many nursery and sick-room recommendations despite being unchanged for well over a decade. It is also 260 watts of a hot electrode boiling water in a room with a child in it, twelve hours to a tank, and an appliance you descale rather than rinse. The 250 sq ft on the box is the most conservative figure Vicks publishes; two gallons a day would hold nearly twice that.
493 sq ft supported · box says 250 sq ft