One-minute review

The changing seasons can make it difficult to precisely predict the indoor temperature and air quality, yet with the Dyson Purifier Hot+Cool Formaldehyde HP09 you can prepare for any eventuality.

At this point, we all know Dyson is king when it comes to all things air, from making some of the best vacuum cleaners to its prolific Dyson Airwrap. Now, it adds the Dyson Hot+Cool Formaldehyde to its collection of bladeless fans, an all-in-one air treatment device packed with smart functionality and wonderful design features.

This makes for a convenient and sophisticated device that removes the need for you to own separate heating, cooling and air-purifying appliances. However, it should come as no surprise that, with it being a sophisticated Dyson product, the Hot+Cool Formaldehyde comes with a fairly hefty price tag – which is one of our biggest gripes with the device. 

However, for that high price it delivers good bang for your buck. Not only can this air purifier destroy the carcinogenic formaldehyde, but it can do so without the need for a replacement filter; its catalytic filter is self-sustaining, trapping formaldehyde molecules into water and CO2. The rest of the filtering is handled by two pairs of replaceable filters: HEPA H13 particulate filters and carbon filters that Dyson claims work with its catalytic filter to remove 99.95% of particles from the air down to 0.1 microns. 

Standing at 30 inches / 764mm tall, the Hot+Cool Formaldehyde is smaller than some of Dyson’s other air treatment appliances, and its 8.6in / 220mm diameter base is pretty space-friendly, meaning it can sit happily on a table or the floor. The fan can be tilted, too, and offers 350 degrees of oscillation, making it easy to optimize airflow regardless of where you position the device.

As you’d expect, the Dyson Hot+Cool Formaldehyde is aesthetically beautiful, with a futuristic – yet not obtuse – design. It’s a little bit of a shame there are no alternative colorways, though; the bronze base and matching remote might not suit every home. 

The Hot+Cool Formaldehyde comes with a remote that attaches to the top of the unit magnetically, but there’s also a sophisticated, easy-to-use app that allows remote control. The latter offers generous insight into the air quality in your home, tracking not only the temperature and humidity, but also the levels of pollutants and particulate matter (PM2.5, PM10, VOC, NO2, HCHO). You can also check on the status of the Hot+Cool’s filters via the app, ensuring they’re replaced in good time. 

Aside from the hefty price, our only real criticism of the Dyson Hot+Cool Formaldehyde is that it lacks the ability to automatically switch on when it detects changes in the air. Otherwise, it’s an absolute dream to have and use around the home, comprehensively caring for your lungs in ways you might not even know you need.

If you prefer to have an appliance which circulates air that is cooled over time then head to our best fans guide. All those featured have been reviewed by a member of the Homes team, and some are more affordable than you may first thing.

Dyson Purifier Hot+Cool Formaldehyde HP09 review: price and availability

•  List price: $769.99 / £699.99 / AU$1,149.00 
• Available in the US, UK and Australia 

The Dyson Purifier Hot+Cool Formaldehyde HP09 will set you back $769.99 / £699.99 / AU$1,149, and is available online at the Dyson store, on Amazon, as well as some local retailers such as Best Buy in the US, John Lewis and Currys in the UK, and JB Hi-Fi in Australia. In the UK, it’s only available in its Gold / White colorway, but in the US and Australia, you can opt for a Gold / Nickel variant.

It comes with a remote and a set of HEPA + carbon filters ready for installation. Replacements cost $79.99 / £65 / AU$99, which Dyson recommends you do once every 12 months to ensure optimal performance.

Price: 3.5/5  

Dyson Hot+Cool Formaldehyde air purifier review: Specs

Dyson Purifier Hot+Cool Formaldehyde HP09 review: Design

• Compact and easily moved 
• LCD screen 
• Bladeless fan 

As is to be expected from Dyson’s high-tech and futuristic devices, the Hot+Cool Formaldehyde is a stylish and svelte unit, taking the form of many of the rest of Dyson’s bladeless air treatment products. 

Measuring 30 inches x 8.6 inches / 764mm x 220mm (H x D), the Hot+Cool Formaldehyde is pretty compact, especially considering the number of features it houses. It’s light enough at 12.6lb / 5.5kg to be moved around your home fairly easily, and the 5.9ft / 1.8m cable is a decent length to ensure it can be positioned where you need it.

The base of the unit is encased in matte gold, with holes through which air is drawn in to be filtered, moving to the top-mounted bladeless ovular fan. It’s here that you’ll find the HEPA and carbon filters; the catalytic filter sits deeper within the machine, filtering out pollutants and particulate matter from the air.

The fan offers 350 degrees of oscillation, and can be tilted up or down. Note, too, that the airflow can be set to move both forward and backward, for those occasions you don’t want the air directly projected at your face. Just beneath the fan is a small LCD that displays live data.

The Hot+Cool Formaldehyde arrives with a matching gold remote, which, rather handily, attaches to the top of the fan magnetically. It’s pretty easy to knock off, though, especially when the fan is tilted.

Design: 4.5/5

Dyson Purifier Hot+Cool Formaldehyde HP09 review: Performance

• Quiet night mode setting
• Rapid purification 
• No automatic features

On test, I was super-impressed by the Dyson Purifier Hot+Cool Formaldehyde HP09, which performed brilliantly for heating, cooling and purifying. 

The fan offers 10 power settings, allowing you to customize the speed of airflow, which spans from a soft waft to a powerful blast of cold or hot air. It’s surprisingly quiet in operation, too; in night mode, the fan auto-adjusts to the soft, quiet level 4, and its lowest setting is whisper-quiet, registering just 40db on our decibel meter – which is the equivalent volume of a quiet library. Even on its highest setting, the Hot+Cool Formaldehyde registered 60dB, which is about as loud as a spoken conversation.

With the app and the controller, you can adjust the Hot+Cool Formaldehyde’s oscillation, rotation, and direction – all of which are incredibly useful if, like me, you find yourself needing to tweak your environment throughout the day.

My apartment is often victim to sudden changes in temperature, and so I was a big fan of its auto mode as a way to keep my workspace at a consistent, comfortable temperature. The device can heat up to 98°F / 37°C (pretty quickly, too), taking my flat from 21°C to 23°C in 15 minutes on its max setting (8.5ft / 2.6m per second airflow) and oscillating by 45°, cooling it quickly and effectively back down to a less uncomfortable temperature.

On the purifying side, I tested the capabilities of my Hot+Cool Formaldehyde by spraying my dry shampoo aerosol near the unit. The device quickly detected the change in air quality, indicating that the level of volatile organic compounds (VOCs) had risen on both the LCD panel and in the app. 

Next, I tried lighting incense and a candle to see how the Hot+Cool Formaldehyde handled the particulate matter. Just a meter away from the purifier, the candle and incense stick spiked the air quality from “Good” to “Very Poor” according to the Dyson app – slightly alarming – but it managed to restore healthy levels within 10 minutes of the purifier being turned on. When I repeated the test without turning on the purifier, it took an hour just to clear the “Very Poor” range.

Dyson doesn’t achieve a full home-run with the Hot+Cool Formaldehyde in my books, largely due to the absence of automatic features. While the device can be toggled within the app to continuously manage the air quality, frustratingly it can’t be programmed to switch on when it detects low air quality. I’m sure there are clever ways to retrofit this feature using home hubs, but not having this as a native feature feels like such a missed opportunity – and it’s a concern that users have raised with previous Dyson air treatment devices.

However, overall I was really impressed by how responsive and rapid the Dyson Hot+Cool Formaldehyde was on test. Since my home has some issues with mould and damp, and is situated right next to a major road, having greater visibility and control over my home’s air quality is a huge boon.

Performance: 4.5/5

Dyson Purifier Hot+Cool Formaldehyde HP09 review: App

• Device maintenance options
• Remote air purifier contrl
• Near-live air quality data

The remote control is great, but it’s the app that swayed me on the overall effectiveness and usefulness of the Dyson Purifier Hot+Cool Formaldehyde HP09.

Connected to the Dyson app, as per other Hot+Cool and air treatment products from the manufacturer, you can keep track of the air quality and temperature within your home, the  lifespan of the filters, and also make use of several fantastic smart features. 

These include the timer and schedule, which will be handy for those looking for a low-maintenance device. In addition, you can also turn on continuous monitoring exclusively through the app, if you want round-the-clock insights into the air quality in your home. Control of the Dyson Hot+Cool Formaldehyde using Siri and Alexa is also possible, making this a fantastic addition to your smart home setup. It’s a little annoying that you have to set this all up in the Dyson app; I much prefer using my Apple Home application and seeing all of my devices in one place. 

It’s a wonderfully easy-to-use and slick app, complete with a virtual controller for those occasions you don’t want to grab the physical one, delivering lots of value-adding information, right down to the levels of specific pollutants in your home. This was best seen via the dry shampoo and flame tests, during which the app presented an overview of the overall air quality, PM2.5, PM10, and VOC levels to help determine how I should treat my air. 

I particularly enjoyed the app’s fan direction control, which allowed more granular control than the physical remote. It’s impressively low latency, too.

When testing the responsiveness of the Hot+Cool Formaldehyde to pollutants, it was a little daunting watching the live data numbers slowly tick up as the volume of particulate matter in my home increased.

App: 5/5

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How I tested the Dyson Purifier Hot+Cool Formaldehyde HP09

• I used the Dyson Purifier Hot+Cool Formaldehyde HP09 and its partner app for 2 weeks
• Stress testing with various substances and measurements

I had the Dyson Purifier Hot+Cool Formaldehyde HP09 in my home for two weeks, and every day I used the device to manage the temperature and air quality within my home. I tried all of the various settings available through the app, as well as checking out the device maintenance options.

To test the air purification monitoring and speed, I sprayed heavy particulate aerosol (dry shampoo), lit a scented paraffin candle and also lit a scented incense stick. I also measured the volume with a mobile phone decibel meter and tracked the changes in room temperature through both the Dyson app and my in-home thermostat.

Read more about how we test.

[First reviewed April 2023]

Two-minute review

The Insta360 X3 is a great all-rounder action camera. Its strength clearly lies as a 360-degree video shooter, although it can capture decent 4K footage with a standard action camera field of view, too, beating the GoPro Max for single-lens clarity. That said, if you mostly shoot single lens videos, dedicated offerings from DJI, Insta360 and GoPro in our best action cameras guide fare better. 

You can use a Insta360 X3 mounted to bike handlebars or a helmet, or you can just hold it and shoot video as you would with a phone. Handheld use is the part Insta360 X3 nails better than a GoPro, which feel like they should be attached to a selfie stick at the very least. The Insta360 X3 also has major usability benefits over any Insta360 camera released to date, mostly thanks to the unusually good screen. 

Insta360 has also nailed one of the most important parts of the pocket 360-camera workflow – editing your footage is a blast, and only takes a few minutes for shorter clips once you have a grip on the fairly intuitive and wide-ranging tools.

Sure, there are some problems. You can’t view all kinds of clips from the camera itself. It takes a beat to start capturing video, and some elements of the image processing aren’t at the same level as GoPro’s. 

However, the Insta360 X3 is one of the best options if you want an action camera that can “do it all”. But is it worth the upgrade for Insta360 X2 owners? We think there’s plenty of life left in that older camera, and the main improvements are a much larger screen and a great new Active HDR mode that avoids blown highlights like a pro. 

Price and availability

• Launched in September 2022
• $449/ £459 / AU$799 RRP
• Seven different kits available

The Insta360 X3 was released in September 2022, two years after the Insta360 X2. It costs $449 / £459 / $799AU, making it just slightly more expensive than its predecessor was at launch. It costs slightly less than the GoPro Max, although you can generally now find that dated camera for less online, while the Ricoh Theta X seems extortionate by comparison. 

Insta360 also offers a bunch of kits for different mounting scenarios — adding in a bunch of accessories. Kits include the Get-Set Kit for $496 / £510 / AU$800 that includes an invisible selfie stick, a 64GB memory card and a lens a cap. Others available include the Snow Kit, Motorcycle Kit, Bike Kit, Bullet Time Kit, Ultimate Kit and Virtual Tour Kit and more details can be found on the Insta360 store. 

• Price: 4.5/5

Design

• Large, clear display
• Includes a 1/4-inch threaded port for a selfie stick
• 10M water resistance

The Insta360 X3 is an upright, stick-like camera, just like its predecessor. There’s a threaded mount point on the bottom, should you want to attach a selfie stick. 

It fits comfortably in the hand, despite the lack of room for any ergonomic grip contouring. And for those interested in the materials used, the sides are plastic with a diamond embossed texture, for extra grip. The front and back are soft touch plastic. No surfaces have the rubberised feel of a GoPro, but the parts you end up worrying about are the glass areas. 

That’s the display glass and, much more important, the lenses. The fear factor is unavoidable with 360-degree cameras, so you might want to buy a lens cover (not included with the standard bundle) or Insta360’s accidental damage insurance. There are no removable, replaceable outer lens elements here. 

Back to the fun stuff, the Insta360 X3 feels right at home in your hand. Just below the screen are buttons that start capturing video and flip between front and rear lens views. In action these are a bit like the navigation keys on an Android phone. Very handy. 

The Insta360 X3 has four physical buttons: two up front, two on the side. But it is largely a touch-led interface, and one that uses a couple of gestures you will need to bed into. 

Flick right and you reach the shooting mode screen. But flick right from the very end of the display and the Insta360 X3 brings up your captured clips instead. It’s the one quirk of the Insta360 interface: needing to disambiguate between horizontal swipes and similar swipes that begin at the screen’s end. 

Once you’re accustomed to that, the Insta360 X3 is largely a breeze. And it looks clear on the 2.6-inch screen. 

The Insta360 X3’s screen is probably the single most important design upgrade here. The modular cameras have tiny little square screens, while in the Insta360 One X2 there is a small round porthole instead. This camera’s portrait aspect screen seems huge in comparison, and is also larger than the GoPro Max’s display. 

You do need to manually max out the brightness to make it hold up in bright sunlight, but it gets roughly as bright as the GoPro Max’s own. The large screen is better for previewing the picture than the last gen model, and makes navigating around the menu system easier. Its interface also just looks a lot glossier and more high-end. 

The style of the Insta360 X3’s screen is geared more at influencers and content creators than the classic action camera audience, though. It’s an upright screen, offering the framing you’ll typically see in videos shared on social networks. The orientation doesn’t auto-rotate if you turn the camera around either. 

However, look a little deeper and you’ll realize this is an entirely sensible move. Holding the camera sideways is only going to bring your fingers closer to the lenses if you’re rolling without a stick. And when you shoot in the single-lens mode, the only drawback when shooting at 16:9 is the preview image is smaller. 

If you are desperate for that full-screen preview, you can get the Insta360 X3 to shoot in 9:16 instead and turn the camera on its side. 

The Insta360 X3 has double the water resistance of the GoPro Max, at 10m/33ft, and matches the GoPro Hero 11 Black. Those planning to dive at anything like a depth of 10m should get the Insta360 Dive Case, though. The additional pressures involved when moving through water means anything below fairly surface-level capture is a bit risky. 

Insta360 achieves the X3’s water resistance using single layer rubber seals around the charging socket and the battery, which pops out when you release its two fastening sliders on the side. 

Our review period did not, unfortunately, coincide with any trips to the beach. Walking and running around with the Insta360 X3, we noticed it does tend to get warm pretty quickly. But not uncomfortably so. We saw no overheating messages after filming constantly for 45 minutes at 5.7K.

• Design 4.5/5

Features and performance

• Stabilization smooths out action a treat
• Powerful editor for modes like timelapse
• Slow start up time

The Insta360 X3 uses an 1800maH battery, notably higher capacity than the 1600mAh of the GoPro Max. Insta360 claims this can last 81 minutes in the 360-degree, 5.7K resolution mode. 

After 15 minutes the Insta360 X3 dropped from 100% to 87%, suggesting it could actually last a lot longer than 81 minutes. However, following 45 minutes of capture it was at 49% battery, closer to the claim. 

What we have here is somewhat non-linear battery reporting. The Insta360 X3 holds onto a 100% charge reading for a little too long, a popular tactic in consumer electronics. It’s not helpful in a more tool-like gadget such as this, but may change over the weeks as the battery settles (and more firmware updates arrive). And the important part: Insta360’s 81 minute battery life rating is not a work of fiction. 

Stabilization used to be one of the classic action camera battlegrounds. It still is at the low-end, but discussing it in Insta360 cameras has now become quite boring. Its FlowState stabilization has been excellent for ages now, and continues to be so. The Insta360 X3 is great for sporty use, or extreme sports use, as long as you don’t mind the way its tall shape will stick up from the mount a bit. 

The 360-degree view means there’s basically infinite scope for stabilization, and the Insta360 X3 has horizon leveling to make this effectively automatic. You can also switch on a feature called Direction Lock when editing your clips, which counters any twisting of the camera so it appears as though you were holding the X3 straight the whole time. 

The Insta360 X3 has a built-in TimeShift mode, which is a form of Timelapse shooting designed to let you use the camera handheld. It doesn’t have the smarts of GoPro’s version, which can automatically shift the footage’s speed up and down based on whether there’s anything interesting going on in the scene. But it’s a quick way to make sped-up clips. 

We do think you get better results by shooting at standard speed and turbo-charging footage in the edit, as Insta360 offers good-looking motion blur and better control over the speed of playback. 

There are parts for Insta360 to address in a future camera or, fingers crossed, a software update. The Insta360 X3 takes a solid couple of seconds to actually start recording clips, and the GoPro Max feels instantaneous by comparison. 

Like most Insta360 launches, we’ve also come across a few bugs. It has frozen on a few occasions, and one low-light mode clip was rendered unreadable for some reason. However, these mostly cropped up when handling footage after a shoot, not actually during capture. 

The Insta360 X3 also has several interesting modes we’ve not discussed yet. Me Mode is one of the neatest. This leverages the slight overlap of the lenses’ vision to produce a flat clip in which a stick used to mount the camera becomes invisible. You’ll still see your arm holding it, of course, but it’s great for no-fuss dramatic shots. Insta360 uses someone jumping into the sea, and snowboarding, as a couple of examples. 

You can capture stills at up to 72MP resolution, in the 360-degree mode. Again, this process is quite slow, but the results are solid — if not as impressive as those of a good phone when trying to capture a more ordinary field of view. 

Insta360’s editing tools are fun and fairly easy to use as well. We tried both the phone app and Insta360 Studio on Mac for this review, and their tool sets are largely similar. 

When re-framing 360-degree footage, you set key frames along the timeline, and Insta360’s software generates smooth transitions between them. You pinch and drag the view in the phone app to perfect each of these key frames, but rotational control is kept separate. This can initially seem a bit confusing, but does make key frame manipulation feel simpler than GoPro’s more free-wheeling approach.

We found the process fastest on a laptop, as mouse control just feels that bit more precise than on a phone-size touchscreen. 360-degree edited clips are set at 1080p when exporting from the phone app or Insta360 Studio, which may seem too limited when maximum res is 5.7K.  However, we saw little obvious benefit after manually changing this to 4K resolution in the desktop Insta360 Studio software. And if you’re looking to produce remotely normal-looking videos, you’re not going to be using all of that raw 5.7K information anyway. 

There’s also a plug-in for Adobe Premiere Pro, but we haven’t tried this as part of the review.

• Features and performance: 4.5/5

Image and video quality

• Active HDR deals with blown out highlights
• Strong 360-degree image quality with limited cropping
• Single-lens videos look better than the GoPro Max

The Insta360 X3 has two 48-megapixel cameras with 1/2-inch sensors and f/1.9 aperture lenses. These are larger and higher-res than the 17MP, 1/2.3-inch sensors of the GoPro Max, and those of the One X2. 

However, these numbers aren’t really aspects to focus on, beyond the one key mode they may help to enable. This is 4K video when shooting with a single lens, rather than in the 360 mode. 

Single lens videos require zero editing – you can pull the resulting MP4 files straight off the camera, ready to go. Its sharpness is significantly better than the single lens mode of the GoPro Max, which is limited to 1080p. Sure, there’s a 1440p mode in the GoPro, but this is 4:3 capture, meaning it’s the same quality as 1080p, just with a taller frame. 

So, are single lens videos a match for those in single lens cameras from GoPro and Insta360? Not even close. We only had the GoPro Hero 9 Black for direct comparison, but that older model has prettier color and much better detail at 4K, particularly out of the center of the frame. These flat videos become quite muggy and basic-looking at the corners of the shot, and look much more like 1080p captures than 4K. 

This was always going to be the case. The Insta360 X3 lenses have to capture a full 180 degrees, the GoPro Hero 9 Black’s do not, and this mode crops into their view substantially. Don’t buy the X3 if 360-degree capture is a “nice to have” extra. 4K flat videos are also limited to 30fps, with 60fps available at a lower-quality 2.7K resolution. 

360-degree video is the main event, and here the Insta360 X3 and GoPro Max find a form of parity. The X3 shoots 360 clips at up to 5.7K resolution, 30 frames per second. Insta360’s secret weapon is Active HDR, which you don’t get in GoPro cameras. This doesn’t affect the frame rate either. 

Action cameras have a bad habit of leaving video clips with odd-looking gradients in skies as the frame errs closer to the sun. Or leaving very significant blown out areas in clouds on bright days. It’s because the small sensors of these cameras have relatively low dynamic range. The Insta360 X3’s HDR mode all but fixes this, at least compared to the standard shooting mode, by merging two exposures per frame. 

Sometimes the results are quite brilliant, and give you loads more highlight detail to play with in the edit. It’s extremely useful when you’re shooting outdoors, or when there’s partial tree cover up top – one of the tricky parts of shooting 360 video is the exposure level is not just judged on what’s in front of you, but your entire surroundings. 

You won’t want to use HDR 24/7, though. It’s no good for low light conditions, because it restricts the exposure time for each frame. And while it has real image quality benefits, I’ve noticed more aberrations in HDR clips, like very obvious noise in a plain blue sky towards the side of the frame — even on a sunny day. 

HDR also has a color character that reminds us of the earlier 2013-2015 days of phone HDR, sometimes leading to unnatural-looking tonality and a slight flattening of contrast. However, this can be fixed in video editing software. Insta360’s own software offers a couple of color and clarity boosting options. I haven’t noticed any ghosting in Active HDR, though, which is the classic issue of HDR video where combined frames are shot sequentially, leading to “afterimage” doubling of moving subjects. 

GoPro currently only offers tone mapping, which is nowhere near as powerful as “active” HDR. But when you get a bit more ambitious with your 360-degree editing, you can’t avoid the slight deficiencies of Insta360’s image processing. 

Zoom in significantly and fine detail can become unconvincing. Tight textures like gravel, tree leaves and the patina of old walls get filled in with too many unnatural-looking straight and horizontal patterns. GoPro tends to avoid these, instead often looking softer, but more natural. 

This is an effect of Insta360’s sharpening, which can be dramatically reduced by simply dropping it down from the standard “high” setting. But it’s a balance. If you want to edit down to a field of view less than 180 degrees, footage does become quite soft-looking with no sharpening at all. 

Night shooting is, as in most other action cameras, quite poor. The larger sensors bring a slightly improvement over the Insta360 One X2, but not a dramatic one. However, there is a timelapse style night mode that dramatically improves results, called StarLapse. You’ll need to use a tripod for it, but it can be perfect for YouTuber-style B-roll footage. 

• Image and video quality: 4/5

Also consider

Testing scorecard