Dreo
Dreo HM512S
A litre more tank than the HM311S and a bigger room-size claim, from the same playbook: demineralisation cartridge in the box, humidity sensor, app, top fill. The 500 sq ft on the listing is the least defensible number Dreo publishes - that room calls for about 2 gallons a day, which would take the 5-litre tank down in roughly 16 hours against the 42 advertised. Treat it as a 250-300 sq ft machine and it is a good one. Against the HM311S it buys a litre of water and an aroma tray for $25; against Levoit's Classic 300S at a similar price it buys the demineralisation cartridge Levoit charges extra for, and gives up the longer-established app.
The room-size claim, reconciled
185 sq ft supported · box says 500 sq ft
The box says 500 sq ft. By the winter load calculation this output supports about 185 sq ft — the claim is 2.7× the room the machine can hold.
Holding 500 sq ft takes about 2.03 gal/day, which drains this 1.32-gallon tank in roughly 16 hr — against the 42 hours Dreo advertises, which is measured at the lowest setting.
What a year costs
demineralisation cartridge three-pack around $18, changed every two months in season. Electricity assumes the rated 32 W for 12 hours a day across a 150-day heating season at 16¢ per kilowatt-hour.
Specifications
Maintenance profile
- Top fill
- Yes
- Replaceable media
- Demineralisation cartridge
Facts, not a score. Which of these matter depends entirely on whether the unit ends up somewhere you will actually clean it.
Features
- 5L top-fill tank
- Demineralisation cartridge included
- Humidity sensor with target setting
- Dreo app and voice control
- Aroma tray
- 28 dB on low
Pros
- Same included-cartridge approach as the HM311S with a usefully larger tank
- Owners report two nights between fills at the settings they actually use
- Aroma tray sits outside the water path, so oils do not end up in the ultrasonic chamber
- Quiet enough for a nursery on its lowest setting
Cons
- The 500 sq ft figure implies about 16 hours of tank, which is a long way from the 42 on the listing
- Cartridges are a recurring cost and Dreo's stated interval is short
- Cool mist only, unlike the HM713S it otherwise closely resembles
- Some owners report the sensor reading high, which makes auto mode stop earlier than expected
What owners say
No owner discussion collected for the Dreo HM512S 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.
Dreo HM512S, head to head
Looked at alongside it
More from Dreo →
Dreo
Dreo HM311S
Dreo does the thing most ultrasonic makers leave to a separate accessory listing: it ships a demineralisation cartridge and tells you when to change it. That single decision is why the HM311S sits in the no-white-dust filter on this site while several pricier ultrasonics do not. The rest is a competent $50 bedroom unit - 4-litre top-fill tank, real humidity sensor, app, 28 dB. Independent testing found it better suited to rooms under about 200 square feet than the 300 on the box, which is roughly where the arithmetic lands too: 300 sq ft wants 1.2 gallons a day and would drain the tank in about 21 hours rather than 32.
195 sq ft supported · box says 300 sq ft
Dreo
Dreo HM713S
Dreo publishes 500 mL/hr for this one, which is 3.17 gallons a day and puts it in the same real-output bracket as Levoit's LV600S at a slightly lower price. It also keeps the demineralisation cartridge, so unlike the Levoit it can run tap water without decorating the room. The 550 sq ft claim is close to what 3.17 gal/day actually supports - around 780 by the psychrometrics - making this one of the few portable ultrasonics whose room-size number is conservative rather than aspirational. The catch is the same as every hybrid: at the output that justifies the claim, the 6-litre tank is empty in about twelve hours.
781 sq ft supported · box says 550 sq ft
Dreo
Dreo HM717S
Eight litres, warm and cool mist, a published 500 mL/hr, and a demineralisation cartridge - on paper the most complete portable in Dreo's line. The extra two litres over the HM713S buy about four more hours at full output rather than the twenty the runtime figures suggest, because the 80-hour number is again the lowest setting. Where it genuinely earns the money is the middle: run it on auto in a 400 sq ft bedroom and it will go two or three nights between fills without a chilly mist or a dusty dresser.
781 sq ft supported · box says 600 sq ft