You've probably seen them. Those sleek, bladeless hoops sitting in the corner of a minimalist living room, looking more like a piece of modern art than a space heater. They’re expensive. Like, "I could buy a decent used car for the price of three of these" expensive. But the Dyson hot & cold series—officially the Purifier Hot+Cool range—is a weirdly polarizing piece of tech.
People either swear by them as the only thing that keeps their bedroom livable, or they dismiss them as overpriced fans. Honestly? Both sides are kinda right.
If you're looking at one of these in 2026, the landscape has changed. We aren't just talking about the old AM09 anymore. We’re dealing with machines like the HP09 Formaldehyde and the Gen1 models that have sensors more sensitive than a moody teenager. Let's get into what actually happens when you hit that power button.
The Air Multiplier Magic (and the Noise Problem)
Basically, Dyson uses something called Air Multiplier technology. Instead of a spinning blade chopping the air and pushing it at you in buffets, it draws air in through the base, accelerates it through a tiny slit in the hoop, and uses physics—the Coanda effect—to pull the surrounding air into the stream.
It feels different. Smooth.
But here is the thing: to move that much air without huge blades, the motor in the base has to spin incredibly fast. On setting 10, it sounds like a jet taking off in your guest room. Dyson’s engineers at the Malaysia Development Centre actually widened the aperture in recent models to drop the noise from 64 to 61 decibels, but don't let the marketing fool you. If you’re trying to watch The Bear with the fan on max, you’re going to need subtitles.
The heating side is where it gets interesting. Unlike a cheap space heater that smells like burning dust the second you turn it on, Dyson uses ceramic plates that never reach the flashpoint of dust. No "old radiator" smell. It draws about 2,000 watts when it’s cranking out heat, which is standard for a heater, but it reaches its target temperature way faster than most.
Why the Formaldehyde Version Actually Matters
A lot of people think the "Formaldehyde" label on the HP09 is just a fancy way to charge an extra hundred bucks. It’s not.
Most air purifiers use carbon filters to trap gases. Carbon is great, but eventually, it gets full and starts "off-gassing"—basically spitting the smells back out. The Dyson hot & cold Formaldehyde models use a solid-state sensor and a catalytic filter.
- The sensor is solid-state, meaning it doesn't dry out over time like gel-based ones.
- The catalytic filter doesn't just "trap" formaldehyde from your new IKEA furniture or flooring; it breaks it down into tiny amounts of water and $CO_2$.
- This specific filter never needs to be replaced. Ever.
If you just moved into a new build or finished a renovation, this is the one feature that actually justifies the "Dyson Tax."
The Reality of the MyDyson App in 2026
The app is where the geeky stuff happens. You get these "POLAR" test results on your phone, showing you exactly what’s in your air. It tracks PM2.5 (smoke), PM10 (pollen/dust), and $NO_2$ (car exhaust).
I’ve seen these things react in real-time. Blow out a candle ten feet away and the app turns deep purple. Fry some bacon? The machine’s Auto Mode kicks into overdrive before you even smell the grease.
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But there is a catch. You've probably heard the rumors about "Dyson screeching." It's a real thing. Some users, especially on the older HP01 and HP02 models, reported a high-pitched whistling or grinding noise after a few months. Dyson has been better about QC lately, but if you hear a "cicada" sound, that’s a bearing issue in the motor. Don't try to DIY it; these things are built like Fort Knox. Use that warranty.
Is It a Real Air Conditioner?
No. Absolutely not.
This is the biggest misconception. The "Cool" in Dyson hot & cold refers to a high-velocity fan. It does not have a compressor. It does not have refrigerant. It will not lower the actual temperature of a room by 10 degrees. It cools you by moving air over your skin. If you’re in a 90-degree room with zero ventilation, you’re just going to be blown by 90-degree purified air.
If you want an AC, buy an AC. If you want a heater that also happens to be the best air purifier on the market, then you're in the right place.
Actionable Steps for New Owners
If you just dropped the cash on one, or you're about to, here is how to not waste your money:
- Placement is everything: Don't tuck it in a corner behind a sofa. It needs to breathe. Place it where it can oscillate 350 degrees to actually circulate the air in the whole room.
- Trust the Auto Mode: Manually setting it to level 10 is a waste of energy and earplugs. Let the sensors decide. It’ll run loud for 5 minutes, clean the air, then drop to a whisper.
- Check your filters: The app will tell you when to change them, but if you live in a high-pollution area or have three shedding huskies, check the physical mesh once a month. Vacuuming the outside of the shroud helps a ton.
- Use the Night Mode: It caps the fan speed and dims the LCD. It’s the only way to sleep with it on.
The Dyson hot & cold machines aren't perfect. They’re expensive, and they can’t replace a central HVAC system. But as a targeted solution for a bedroom or a home office—especially if you have allergies—they’re in a league of their own. Just don't expect them to turn a heatwave into a winter wonderland.
To get the most out of your machine, download the MyDyson app immediately upon unboxing and run the initial "Deep Clean" cycle if your model supports it. This calibrates the sensors to your home's baseline air quality. Keep the remote magnetized to the top of the loop; those things are notoriously easy to lose in couch cushions, and a replacement will set you back about $30.