Dyson
Dyson Purifier Humidify+Cool Formaldehyde PH04
A thousand dollars, and the humidifier is the third thing it does. The PH04 is primarily an air purifier with a formaldehyde-destroying catalytic filter and a fan, into which Dyson has fitted an evaporative humidifier with a UV-C water treatment stage and a deep-clean cycle. Judged as a humidifier it is modest: a 1.1-gallon tank, a 400 sq ft claim, and no published output rate at all, which for a company that publishes airflow in litres per second is a conspicuous omission. It belongs in this catalog because people cross-shop it, not because it is the best way to spend $1,000 on humidity.
The room-size claim, reconciled
Holding 400 sq ft takes about 1.62 gal/day, which drains this 1.11-gallon tank in roughly 16 hr — against the 36 hours Dyson advertises, which is measured at the lowest setting.
Dyson publishes no output rate for this unit, in its manual or on its product page. That makes the coverage figure impossible to check against anything, which is worth knowing before paying for it.
What a year costs
Dyson's combined HEPA and carbon filter runs roughly $90 and is rated for about a year of use. 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
Dyson says an ultraviolet cleanse exposes the water to UV-C light, which it states kills 99.9% of bacteria in the water before humidification. 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
- Filter, 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
- Air purification with a sealed HEPA H13 filter and a formaldehyde-destroying catalytic filter
- Fan with oscillation and a backward-airflow mode for purifying without a draught
- UV-C water treatment stage
- Automatic deep-clean cycle
- App control and on-unit air-quality readout
- Humidity target with auto mode
Pros
- Genuinely replaces three appliances, which is the only frame in which the price is defensible
- The air-quality sensing and readout are the best in this catalog by a distance, because that is Dyson's actual product
- The deep-clean cycle and UV-C stage address the hygiene problem more thoroughly than any other evaporative here
- Backward-airflow mode means it can humidify and purify in winter without blowing cold air at anyone
Cons
- No published output rate, which makes the 400 sq ft claim uncheckable - unusual for a company that publishes everything else
- Roughly $90 a year in combined filters, the highest consumable bill in the catalog
- $1,000 buys, as a humidifier, about what a $70 Vornado delivers
- A 1.1-gallon tank in a machine this size and price
- Bottom-fill tank in a unit that weighs 18 lb
What owners say
Summarised from owner discussions and long-form owner reviews. Nobody here has used this unit.
People cross-shop this against dedicated humidifiers, which is why it belongs here, but the comparison it wins is a different one. As an air purifier with a fan and a formaldehyde-destroying filter, it is a serious machine with the best sensing in this catalog. As a humidifier it is modest, and Dyson does not publish an output rate for it — which for a company that quantifies everything else about its airflow is a notable silence.
The practical consequence is that the 400 sq ft claim cannot be checked against anything. Owners weighing it against a Carepod or a classic wick unit are choosing whether they want one appliance doing three jobs or one doing a single job well, and on humidification alone the dedicated units win on both capability and cost. The filter bill is the highest here.
What owners like
- Genuinely replaces three appliances, which is the only frame in which the price makes sense
- The air-quality sensing and readout are the best here by a distance, because that is Dyson's actual product
- The deep-clean cycle and UV-C stage address hygiene more thoroughly than most evaporatives
- Backward-airflow mode lets it humidify and purify in winter without blowing cold air across a room
Common complaints
- No published output rate at all, which for a company that publishes airflow in litres per second is a conspicuous gap and makes the 400 sq ft claim uncheckable
- Roughly $90 a year in combined filters, the highest consumable bill in this catalog
- As a humidifier it delivers about what a $70 unit does
- A 1.1-gallon tank in a machine this size, with a bottom-fill design on an 18 lb unit
Questions owners ask
Is it a good humidifier?
Why is there no output figure?
What does it cost to run?
What does the UV-C stage do?
Dyson Purifier Humidify+Cool Formaldehyde PH04, head to head
Looked at alongside it
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Ten-year warranty, eight watts at full speed, no wick and no filter - Venta's disc-stack airwasher is built to a standard that makes the price make sense over a decade rather than a season. Its manual is also the only one in this catalog that states the assumption behind its room-size figure: "listed square feet are based on 8-foot ceilings". That single sentence is more transparency than the rest of the category manages combined. What Venta will not tell you is how much water it actually moves - no output rate appears in the manual or on the product page - so the 485 sq ft figure has nothing behind it that a buyer can check.
Canopy sells cleanability, and on that promise it delivers better than anything else here: tank, tray, cap and grille all go in the dishwasher, the filter is on a 45-day clock the machine reminds you about, and because it evaporates rather than atomises there is no mist to land on anything. What $159 does not buy is capacity or control. There is no humidistat, and 2.5 litres across the advertised 36 hours is under half a gallon a day - a figure that supports something closer to 110 square feet than the 500 on the listing. As a nightstand appliance for one person's immediate airspace it is excellent. As the 500 sq ft room humidifier the marketing describes, it is not close.
108 sq ft supported · box says 500 sq ft
Mechanically the Bedside 2.0 with a different light and a sound machine tuned for a nursery, plus a baby-safe aroma kit rather than the adult one. The argument for it in a child's room is specific and good: no visible mist means nothing lands in a cot, no ultrasonic means no white dust in a room where a baby is breathing, and the dishwasher-safe parts mean the cleaning actually gets done at the interval it needs. The same capacity ceiling applies - this is one cot's worth of air, not a 500 sq ft nursery - and there is no humidistat to stop it when the room is where you want it.
108 sq ft supported · box says 500 sq ft