Dyson Hot+Cool Formaldehyde HP09 air purifier review

Dyson's latest Hot + Cool product now cleans even more unwanted pollutants out of the of the air with its HP09 Formaldehyde model.

Dyson Pure Hot + Cool Formaldehyde on kitchen counter
(Image credit: Dyson)
Ideal Home Verdict

The Dyson Purifier Hot + Cool Formaldehyde may not make too much of a case for removing its namesake from your home, but it's still a great product from the air quality leaders that has some other hidden improvements.

Reasons to buy
  • +

    Works as a purifier, fan and heater in one

  • +

    Timer and auto shut-off

  • +

    Gold/copper design looks great

  • +

    20% quieter than previous models

Reasons to avoid
  • -


  • -

    Not a huge step up if you're clueless about formaldehyde

Dyson's latest Hot + Cool product now cleans even more unwanted pollutants out of the of the air with its HP09 Formaldehyde model.

We put the machine through its paces to see how useful it is for daily life but, if you want to see how other brands did in our tests, take a look at our guide to the best air purifiers.

Dyson Pure Hot + Cool Formaldehyde

Dyson Pure Hot + Cool Formaldehyde Air Purifier

(Image credit: Dyson)

Dyson Pure Hot + Cool Formaldehyde: Features and specs

Room coverage: up to 27m2
Noise: 46-63dB
Dimensions: H76.4 x W20.5 x D13cm
Weight: 5.7kg

If you've ever used a Dyson air purifier product then set-up for the HP09 will be incredibly simple. It arrives without the filter pre-installed, but the instructions for doing this and then popping the gold outer casing is quick and easy.

Once you've plugged in your new purifier, simply download the Dyson Link app and add the device. The app can download air quality information for your area so you can compare outdoor air quality with indoor, tracking overall AQI, temperature, humidity, PM2.5, PM10, NO2 and pollen.

The indoor trackers also include VOCs and HCHO (that's the formaldehyde) and if you're ever unsure what it all means, there are helpful information pages within the app.

What is formaldehyde?

We wouldn't blame you if you haven't really thought too much about formaldehyde in the home before now, but Dyson is keen to make you more aware. A colourless gas that can be released by furniture, paint, wallpaper or cleaning products, the particles are so small (500 times smaller than 0.1 microns) that most air purifiers and clean air products can't detect it.

Alex Knox, vice president of Environment Care at Dyson had this to say: “The off-gassing tendency of formaldehyde means that it can go undetected in a home for years. Dyson has engineered a machine that provides accurate and successful sensing, capture and destruction of the pollutant. Our solid-state sensor doesn’t dry out overtime, lasting the lifetime of the machine.

The COVID-19 pandemic has raised global awareness about the air that we breathe and Dyson’s commitment to providing cleaner air through innovation and technology remains at the forefront of our mission.”

Our experience

There's no denying that Dyson air purifiers are great products - offering a 3-in-1 service with cooling, heating and purifying all at once - which is why they've remained so popular even while competitors have begun to catch up technology-wise.

We found that the HP09 performed best when heating, which you can set on a timer to make getting out from under the covers less painful on chilly mornings. The in-built thermostat lets you set the machine to only heat your home when the indoor temperature falls below a certain level, which also helps save energy.

We had it set at 21 degrees centigrade in time for 7am which, in mid-April, meant that the heater helpfully came to life just as we were waking up.

Unfortunately the cooling function doesn't have the same customisation, and has more to do with purification than it does altering the room's temperature. Upping the fan speed (which goes all of the way up to 10) is a good way of speeding up cleaning if you want to get rid of a bad smell, but it won't bring the temperature down.

Air purification is as good as ever, with a quick reaction whenever something invades your space. Whenever we sprayed an air freshener or other aerosol it whirred into action and made quick work of the pollutants and, while it wasn't 100% effective against cooking smells, we've yet to test an air purifier that is.

You can see all of this with the app as well as on the small LED screen on the front of the purifier itself. The remote allows you to cycle through the views, while you can set timers and routines through the app.

Dyson Pure Hot + Cool Formaldehyde being controlled by man using app

(Image credit: Dyson)

Dyson Pure Hot + Cool Formaldehyde: Design

The only big design difference for the HP09 Formaldehyde is a splash of gold. Appearing more of a bronz-y gold in real life (see image below), it really does look appealing - especially if you're not a fan of the usual silver aesthetic.

It still looks very futuristic so won't be for everyone, but will blend into softer design styles more easily than some other models from Dyson.

You can angle the machine however you like by dislodging the tower from the base slightly to activate tilting, and the oscillation features means you can also have it automatically fill the whole space with heat/cool air. Or, if you don't want it to produce either, it will simply purify by gently releasing clean air from the sides rather than the front.

Dyson Dyson Purifier Hot + Cool Formaldehyde in front of white door on light wood floor

(Image credit: Future PLC)

Dyson Pure Hot + Cool Formaldehyde: Our Verdict

Dyson's attempt to update its iconic air quality products is admirable, and the new model's ability to filter out even smaller particles is certainly a good thing, but it's unclear whether the Formaldehyde angle will capture many people's curiosity.

Which would be a shame, because the new purifier is as excellent as you would expect from Dyson at this point, and is a good investment that can be used all year round as a heater, fan (or techy accent piece) and air purifier. Of course, if you're more interested in a standalone, take a look at our guide to the best fans.

The other updates such as a 20% noise reduction and full HEPA filtration (now for the entire machine rather than just the filter) make this a great buy, but might not be quite enough to convince those who already have a Dyson at home to upgrade.

About this review

We test all of products at home to accurately determine whether we should recommend them to readers. Caroline writes about technology and smart home gadgets for Ideal Home and has tested multiple air purifiers within a small studio that includes a kitchen (smells!), bedroom (candles!) and an outside area facing a busy road (pollution!).

Caroline Preece
Caroline Preece

Caroline is the smart homes editor for Ideal Home, bringing her background in ecommerce and technology journalism to the homes world since the start of 2021. She has been in the industry for more than a decade, working for magazines and websites across industries as including IT Pro, Expert Reviews, Coach and The Week. Her main passion is for how technology can make people’s lives easier and more fun, as well as how smart home devices can save us all money and time.