Honeywell
Honeywell HCM-350 Germ Free Cool Mist
No longer sold by Honeywell in the US Honeywell's own store lists the HCM-350 as discontinued and no longer available for purchase (October 2026) and points to the HEV320 as its replacement. Shown for comparison; the HAC-504 wick it uses is still sold.
The long-running default in this category, and the arithmetic explains why. Honeywell's manual gives 2 gallons a day of output against the 500 sq ft it is sold for - a room that needs almost exactly that - making this one of the few portables in the catalog whose coverage number the physics supports outright. It was sold from 2011 largely unchanged until Honeywell discontinued it; the tank and tray go in the dishwasher, and it evaporates rather than atomises, so there is no white dust. The costs are a wick habit, a fan you can hear, and no humidistat at all: three speeds, and you are the humidistat.
The room-size claim, reconciled
493 sq ft supported · box says 500 sq ft
The 500 sq ft on the box is what the winter load calculation supports for this output — one of 18 units here whose claim lands within 5% of its own published rate.
Holding 500 sq ft takes about 2.03 gal/day, which drains this 1.1-gallon tank in roughly 13 hr — against the 24 hours Honeywell advertises, which is measured at the lowest setting.
What a year costs
HAC-504 wick filters run about $15 each and Honeywell asks for a change every one to two months in season; the $30 assumes two a season, so hard water or a long winter costs more. Electricity assumes the rated 60 W for 12 hours a day across a 150-day heating season at 16¢ per kilowatt-hour.
Specifications
A claim the maker makes
Honeywell says UV technology in the water reservoir kills up to 99.9% of bacteria, mould, fungus and virus 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
- 2 gal/day published output against a 500 sq ft claim
- Tank and reservoir parts are dishwasher safe on the top rack
- Evaporative - no white dust, tap water is fine
- Three speeds
- UV reservoir treatment
- HAC-504 wick filter, widely stocked
Pros
- One of very few portables whose stated room size stands up to the output it publishes
- The tank and tray are top-rack dishwasher safe, which makes the weekly clean genuinely easy
- Evaporative, so tap water is fine and nothing settles on furniture
- Honeywell still sells the HAC-504 wick, so a unit already in the house stays usable after the model's discontinuation
Cons
- No humidistat of any kind - it runs at the speed you set until the tank empties
- The fan is audible at every speed; light sleepers run it on low or in another room
- Wick filters are around $15 and need changing every month or two in hard water, which is the real cost of ownership
- Bottom-fill tank has to be carried to the sink and inverted
- The UV claim is Honeywell's, made for the water in the reservoir, not for the air in the room
The pros and cons above are drawn from the maker’s documentation and published specifications. There is not yet a body of owner reports for this model that we have read.
What owners say
No owner discussion collected for the Honeywell HCM-350 Germ Free Cool Mist yet. The pros and cons above come from the maker's documentation and published reviews, 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.
Honeywell HCM-350 Germ Free Cool Mist, head to head
Looked at alongside it
More from Honeywell →
Honeywell
Honeywell HEV620 Top Fill Tower
Honeywell's answer to the two complaints levelled at the HCM-350: no digital humidistat, and a tank you have to carry upside down to the sink. The HEV620 is a tower with a top-fill opening, a digital humidistat that will actually hold a target, and a timer. Its 300 sq ft claim against 2 gallons a day of output is one of the most conservative ratios in the catalog - the output supports closer to 490 - which is worth knowing if you have been talked out of it by a spec-sheet comparison against an ultrasonic promising 750. Honeywell now sells it in black (HEV620B); the white HEV620W pictured is discontinued.
493 sq ft supported · box says 300 sq ft
Take the HCM-350's mechanism and move the fill to the top: water goes in through a funnel on the lid, so nothing has to be carried to the sink, and that is most of what "Easy to Care" means. The trade is capacity: a 1-gallon tank against the 350's 1.1, no UV, and no humidistat here either. Neither Honeywell's manual nor its store page says any part is dishwasher safe, unlike the HCM-350, whose tank and tray are. At the 36 hours Honeywell claims it is moving two thirds of a gallon a day, which is a bedroom's worth; the 360 sq ft it is sold for would take closer to 1.5 gallons a day and drain the tank in about 16 hours.
165 sq ft supported · box says 360 sq ft
Honeywell's filter-free line exists because plenty of people would rather buy no consumables than buy the right ones. There is no wick and nothing to replace, which keeps ownership about as cheap as it gets here - and it is an ultrasonic with no demineralisation media, so on hard water the minerals that a wick would have caught end up on the furniture instead. A gallon tank and 24 hours works out to about a gallon a day, near enough to what its 300 sq ft claim needs, making this one of the more honest small ultrasonics on that particular number.
246 sq ft supported · box says 300 sq ft