Dyson Pure Hot + Cool Formaldehyde HP09 review: Dyson's best air purifier fan (and heater!) ever

Here's the Dyson HP09 Pure Hot + Cool Formaldehyde review in a big, windy rush: it's Dyson's best fan, best heater and best air purifier ever, all in one understated package. Okay, understated by the standards of a gold fan that costs £500, $750 or AUS$900. With the mercury rising in the UK, you might well be considering shelling out for one.

Known by the code name HP09, and variously referred to as Pure Hot + Cool, Pure Hot+Cool and Purifier Hot + Cool – thanks Dyson marketing team – this combined fan, heater and purifier is the best air purifier Dyson has made to date. And also the best fan. And its best heater. It's a triple whammy!

This is largely thanks to the honing of the features of previous, similar Dyson fans. There are also some new features but how much you are swayed by them depends on how much fear you have of formaldehyde. In the West, this is largely known as something embalmers use. However in the Far East, it is widely recognised as a pollutant given off by paint, cleaning chemicals and, probably, the embalmer next door. 

Since none of wants to be embalmed, we can perhaps all one day recognise that removing formaldehyde from the air is a Good Thing.

Anyway, whatever your thoughts on that, the Dyson HP09 Pure Hot + Cool Formaldehyde has even better all-round build and design quality than previous Dyson efforts and also seems to be more effective at both detecting airborne foulness, and removing it.

Let's take a big lungful of fresh, formaldehyde-free air and see what makes this Dyson HP09 oxygen triathlete a winner.

Dyson Pure Hot + Cool Formaldehyde HP09: price, availability and release date in USA and Australia

In the UK Dyson Pure Hot + Cool Formaldehyde costs £599 and is on sale now. In the USA, it will cost $749.99 from May 6 2021. In Australia, it will be AUS$999 from May 27. 

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Dyson Pure Hot + Cool Formaldehyde: design and build quality

Dyson has fan-making down to fine art at this point, and it has refined the design of the Pure Hot + Cool so it feels more premium than ever. 

Everything fits together easily and with a pleasing clunk when setting up. The oscillation is like poetry in motion, as the fan seems to almost float while swaying gently from side to side.

Admittedly, the Dyson Pure Hot + Cool Formaldehyde is also a kind of muted gold colour, perhaps nearer to bronze in fact. There's no getting away from that because it's the one and only colour option. It's about as classy as a gold fan could possibly look, but I'd much rather have the usual Dyson silver-grey/white/primary colour look, personally. 

Colour aside, this has the standard Dyson heater/fan look. Dyson's purifier fans with a heating element are invariably more squat than those without and my first impression was that the new model is less attractive than the old Pure Cool, which is taller and in silver and white. But it has grown on me.

The remote control is impeccably tactile, useful and gold in colour. You may not need it though as all its functions – and more – can be taken on by the Dyson Link app on your phone. You are much less likely to lose your phone down the back of the sofa than the remote, for a start. If you like, you can also place the remote on top of the fan, where it will dock via the miracle of magnetism. Sweet.

Overall, the Dyson Pure Hot + Cool Formaldehyde serves up the kind of premium experience you'd expect from a pricey fan that also filters embalming fluid out of the air.

Dyson Pure Hot + Cool Formaldehyde: features

As its name suggests, Dyson Pure Hot + Cool Formaldehyde is an air purifier, heater and cooling fan. And one, I might add, that also filters out formaldehyde. It's the successor to Pure Hot + Cool, logically enough. 

Dyson has larded this one up with an even more advanced filtration system than its previous air purifiers. Not only does it have a HEPA filter, but the entire machine is sealed to the HEPA standard. The particle, NO2, VOCs, temperature and humidity sensors of the old Pure Hot + Cool are joined by an 'intelligent formaldehyde sensor'  that 'does not dry out' – this is an issue with lesser formaldehyde sensors, I have learned. 

In addition, this multi-purpose air mover can heat the room to a temperature of your choosing and cool it down (a bit) via Dyson's non-buffeting fan. As noted above, operation can be via the chic little remote or the Link app, but not via the Pure Hot + Cool Formaldehyde's on-body controls, because there are none.

Is Dyson Pure Hot + Cool Formaldehyde any good?

In short: yes. I've used all the previous Dyson air purifiers and a terrifying array of rival air purifiers from other brands – including 2 in the same room as it, during the writing of this review. And I can say with some certainty that the Dyson Pure Hot + Cool Formaldehyde has better, more sensitive sensors than anything else, and also clears the air faster than any other purifier of its size.

When you then add its effectiveness as a fan and heater, you've got a pretty great product overall.

Air purifiers are a hard thing to 'review' if you don't have access to a laboratory. I know that Dyson tests their kit at great length and to a standard they claim exceeds the statutory norm. So for now I am going to have to take it on trust that the Pure Hot + Cool Formaldehyde is filtering out allergens, particles, gases and, yes, formaldehyde to a high standard. 

What I can say for sure is that it goes into action at the faintest hint of pollutants, allergens or cooking fumes and does not let up until the air is properly clean. Long after other purifiers have decided, 'that'll do', the Pure Hot + Cool Formaldehyde continues to scrub the air, whilst showing you its progress via various scary-looking graphs on the  Link app.

Dyson's Link app was quite a buggy and unwieldy thing in its early years, but Dyson has really honed it. Pairing with an iPhone took under a minute and everything connected first time, which would not have been the case a few generations back.

Once the app is up and running, it duplicates the functions of the remote, and it's at that point that I tend to lose the remote under the sofa and never worry about it again. You can also check the remaining life of your filter and set periods when the purifier is 'sleeping'. Such as, for instance, when you are 'sleeping'. 

You can also precisely set the two points between which the fan will oscillate, without having to get up and move the base, which is remarkably satisfying. The range of oscillation can also be varied between 45º and a near-full circle.

Another noticeable improvement over previous Dyson purifier/heater/fans is reduced noise. Certainly when it's on full blast you still won't want to sleep next to it, but maximum volume has been cut from 64dB to 61dB. 

At slightly lower power settings Dyson Pure Hot + Cool Formaldehyde is really very quiet and even when working flat out, I can still hear the TV over it fine.

The best thing to do with this air purifier is to leave it on auto mode and let it do its thang and that's the case here. I found that cooking, cleaning, lighting a candle, extinguishing a candle and using embalming fluids all reliably sent the machine whirring into overdrive. At this point, you can always opt to manually reduce the purifier's speed to a lower one. The result is quieter operation but, obviously, a longer period of time to clear the air.

Of course, if you cook some steaks on a searingly high temperature grill pan and fill the room with meaty smoke, this Dyson is not going to magically clear that on its own in a matter of minutes. At least not until you conclude cooking and open a window. However for everyday air fouling, unwelcome particles from pets and people, cleaning chemicals and so on, it's reassuringly rapid. Used in conjunction with proper kitchen extraction, it definitely helps with cooking smells too.

The heating function also works well – just set the room temperature you desire and it'll keep working till that's reached, plus a little bit. You can also set the rate at which it pumps out air, to keep the volume down if necessary. The fan, too, is very pleasing, in the usual Dyson way – cooling without 'buffeting', as they say. 

Another very useful feature is that you can have the filtered air come out of the back of the fan rather than the front. This is genius, actually, and means that  you can have the air purified without a gale being blown directly at  you. That's not so useful in summer perhaps but in a cold room in winter, it's very nice indeed.

Should you buy the Dyson Pure Hot + Cool Formaldehyde?

If you have been waiting for Dyson to achieve Peak Fan, the Pure Hot + Cool Formaldehyde is it. It does everything you could reasonably wish for from a fan/heater, looks great, so long as you don't mind 'off-gold' as a colour. It also provides good peace of mind that your room's air is clean, and free from formaldehyde. 

It will be interesting to see what innovation Dyson shoe-horns into its next air purifier. Whatever it is, it's hard to imagine it'll be significantly better than this.

Also consider…

According to the replacement filter section of the Dyson website there will also be a Dyson Pure Cool Formaldehyde, ie: the Dyson Pure Hot + Cool Formaldehyde without the heating part. It looks taller and sexier but we don't have any details beyond that. It could also just be an error on the Dyson site, of course.