Dyson Pure Hot+Cool Purifier Fan Heater review

Before we get into what's wrong with the Pure Hot+Cool, let's take a look at what's right. It's a nifty little machine in a lot of ways. As a heater, the Pure Hot+Cool operates like a thermostat - you tell it what temperature you want the room to be, and it will pump out hot air until the room reaches that temperature. From there, the device simply monitors the temperature and responds as needed, which is certainly appealing from an energy-efficient stand-point, especially if you're looking at heating a large room.

As a heater, it's also pretty powerful, warming up my living room of 15.8 metres square quickly and efficiently so that no matter where I sat in the space, I felt pleasantly toasty. The Dyson is so powerful a heater that I would advise not using it in too small a space. Because it's responsive, when you first switch it on it starts to pump out hot air at a fierce rate - to bring the room up to your desired temperature. That can feel way, way too hot if you're sitting too close.

The responsive nature of the device is also key for air purification. The Pure Hot+Cool monitors the air quality of your room, which means that as long as it's in "auto mode", it can respond only as needed, rather than constantly cycling air through its filter regardless of whether or not it's toxin and dust-ridden or fresh as a mountain breeze. Purifying in this manner extends the life of the filter inside the device, which is something worth doing, considering a filter costs $99 to be replaced. Dyson says the Pure Hot+Cool filter needs to be replaced every 4,300 hours, or less if you're in a dirty environment. That's about 180 days of constant use, or about once a year if you're using it for about 12 hours per day.

The Dyson Pure Hot+Cool is a HEPA-type filter that provides real-time feedback about the quality of the air in your space, which was reassuring and a great way to get a sense of what's going on inside your home, in terms of air quality. A little round panel on the front of the device shows you your room's air quality with a simple colour-coded diagram. And if you want more detail you can dive into the app which shows real-time data as well as a month's worth of historical data, and lets you know what's happening in terms of individual air pollutants including pollen (PM 10), bacteria (PM 5.0), industrial emissions (PM 2.5) and others. This real-time reporting and app functionality are premium features not found in Dyson's cheaper Pure Cool Me product.

In my case, what I learned from the device was that the air quality in my apartment is fine. I had ratings that were in the green "good" category pretty much all of the time. So to check the machine was working I walked around the room spraying Mortein. The Dyson picked up on the presence of chemicals within a few seconds when I sprayed up close, and within about twenty seconds when I sprayed further away. And it brought the air quality in the room back from the red zone and into the green within a few short minutes.

When it comes to controlling the Dyson Pure Hot+Cool, you have the option of using either the remote control provided or an app which can be downloaded and installed on your phone for free. I preferred using the app for controls as there are quite a few different buttons to think about and on the app, they're labelled whereas on the remote they're not.

As well as setting the temperature and fan speed, with the remote, you can choose from several oscillation patterns from 90 degrees through to 350 degrees, and also set the machine into "diffused mode" if you want to keep purifying your air but don't need the heater or fan function operating.

With the app, you can also set a timer on the machine and even a schedule to switch it on and off at specific times of day on specific days of the week. If you're using it at night, there's a "night mode" that dims the screen and limits the fan speed to a max of four (out of ten possible settings) to keep noise to a minimum.
it brought the air quality in the room back from the red zone and into the green within a few short minutes.

• Cooling lacks oomph
• Fan wears out the filter

Where the Dyson Pure Hot+Cool falls down is its cooling function. It's just not as powerful. When you're sitting up nice and close to the machine on a hot day, the effect is very refreshing, especially on the higher fan speed settings. But the fan just doesn't hold its own in larger spaces. When I sat just a couple of metres away from the device it felt less like a fan and more like a gentle breeze. When I sat four metres away, I honestly couldn't feel the fan at all.

To put that in context, last summer I bought a Mistral pedestal fan from Bunnings for about $100. The Mistral can cool me from four metres away no problem. Its highest speed setting, if anything, is too powerful (as my partner has complained about on more than one occasion).

The gentle breeze effect from the Dyson is nice, but in the height of an Australian summer, I know which fan I would want to keep my living room cool. And frankly paying $899 for a fan you have to sit right next to for a proper cooling effect seems pretty unsatisfactory to me.

There's also the fact that, in its fan setting, the Dyson Pure Hot+Cool isn't nearly so efficient as a purifier. As we've discussed, in "heat mode" the Dyson senses the air temperature of the room and adjusts its activity accordingly. However, it doesn't behave the same way in "cool mode". Instead, you simply adjust the fan speed up or down depending on how hot and bothered you're feeling.

Adjusting the fan speed immediately switches auto mode off. Which means that your machine will apply the same amount of power to purifying your air whether it's super fresh or toxic. The result is your filter wears out faster, and you're finding yourself shelling out $99 to replace it more frequently. That's not ideal.

It also means you're not getting the same energy efficiency benefits in summer as you are in winter when the Dyson controls its energy use in response to room temperature.

On top of all that, in the two most powerful fan settings - 9 and 10 - the Dyson Pure Hot+Cool tends to whistle. Not all the time. But again, for $899, that's just not good enough.