Review: Dyson Hot+Cool Air Multiplier (AM05)

19 Mar 2013

They say that necessity is the mother of all invention. And while the technology industry outdoes itself in its quest to come up with the shiniest, smartest and most sophisticated equipment that consumers will relish, they often forget life’s most essential necessities.

A smartphone will never keep you warm or clean. TVs entertain and inform and vehicles get us from A to B. But what I always admired about inventor James Dyson is his penchant for creating useful things for erstwhile ordinary tasks, while at the same time pushing engineering and physics to their absolute limits.

Dyson strikes me as an inventor on a quest for perfection. It is clear he has never forgotten the earliest frustrations that come with sticking to one’s vision in a world that seems unwilling to accept that vision. Last week, in an interview with, he reminded us how his earliest requests for funding were met with refusal from the bank manager and he had to borrow money against his family home to bring his vision to reality.

Today, Dyson’s company is a global giant employing more than 4,600 people with revenues of stg£1bn and profits in excess of stg£100m. He has been knighted and his personal net worth in 2011 has been estimated at stg£1.45bn.

So bear all that in mind the next time someone rubbishes your ideas or before you blithely dismiss the notions of others.

Dyson Hot+Cool

The interesting thing to note about Dyson is what his inventions do. His vacuum cleaners clean more efficiently than competing devices from household names. He has created hand driers that wash and clean your hands and heaters that heat rooms evenly.

So the technology industry wants to create smaller processors and higher-definition cameras and social networks that keep us all connected. Well and good, but in tackling the necessary and seemingly mundane tasks of just being alive, Dyson is doing us all a big favour.

Whenever his people have something new to reveal, their excitement and giddiness is palpable and in the case of the Dyson Hot+Cool I think they’ve stuck gold.

First impressions

This isn’t a new technology from the Dyson stable, moreover it is a leap forward in the engineering behind the original idea.

The first Dyson air multipliers promised to help heat a room faster and in a more even, energy-efficient way. In the case of the newest model, the Hot+Cool, Dyson’s engineers have increased the output of the brushless motor by 33pc.

The Hot+Cool continues its object of heating up a room in a fast and even way, but because of the increase in the output of the motor boosts cooling performance is increased mightily. So, it keeps you warm in winter and cool in the summer.

The new technology promises to take the stuffiness that occurs with room heaters, whereby one part of the room gets the heat but the bad air quality while the rest of the room remains positively Baltic.

I think it does that quite well and I was amazed at how quickly rooms heated. I was also quite taken aback by how after heating a room the ceramics on the device remained cool to the touch. That was quite magical, I have to admit.

Before I get into the engineering behind this feat, what I think makes the Hot+Cool a winner is its appearance. The industrial designers deserve top marks for creating something functional and quite stunning to look at.

The Hot+Cool is covered in a chrome coating that makes it statuesque but discreet at the same time. The one I reviewed was nickel/nickel coloured and because of its silvery appearance, it can sit in any room without seeming out of place because the reflective surface actually absorbs the colours. For example, in a room with a lot of colours going on – like your typical living room – the device doesn’t add to the clutter. This is unlike most other room heaters which announce themselves by their colour – mostly beige – and their noise.

While the Hot+Cool isn’t entirely silent, it is quiet and its sound only builds as you increase the fan’s intensity. You can reduce the fan intensity to between one and 10 levels but at the same time maintain it at the temperature you want between one and 28°C.

The ability to turn the machine simultaneously into a cooling device is remarkable and because the machine oscillates (ie, it moves from left to right at the touch of a button), I would imagine it will prove to be a godsend during the stifling days and nights of summer.

Another factor worth noting is the safety – if your household includes children, cats or dogs then it is likely accidents will occur from time to time. If the Hot+Cool for any reason is knocked over, it automatically cuts out and is one thing less to worry about.

The controls for the machine only add to its slick appearance. It comes with a handy little remote control that lets you increase the fan’s intensity or lower it, increase the heat in the room or switch to cooling mode and get the machine to oscillate left to right to spread the air current.

The same controls also exist on the front of the device and a handy LCD screen tells you the current power of the fan and the room temperature option you’ve selected.

The engineering

The Hot+Cool is the product of the labours of 45 engineers who did everything possible to give the device a 10-year lifetime – this involved everything from electromagnetic testing, acoustics and aligning air currents using Laser Doppler Anemometry.

The machine is bladeless and draws in 28 litres of air per second via a mixed flow impeller. Nine asymmetrically aligned fins, with rows of tiny holes, reduce friction caused by the colliding high and low pressure air maintaining a constant smooth airflow. 

During heating, the air travels over ceramic stones, self-regulating the heat transferred. The air is then accelerated through a 2.5mm aperture within the loop amplifier. This creates a jet of air that passes over an airfoil-shaped ramp angled at 5 degrees.

During testing in Dyson’s own environmental chamber, the machine simulated temperatures from 5°C to -80°C and 10pc relative humidity to 80pc.

In terms of energy efficiency, an intelligent thermostat maintains the temperature between 1°C and 29°C, and when it hits the desired temperature the machine will turn itself off. If the thermostat senses a drop in temperature it will switch itself back on to readjust.

The machine weighs just 2.5kg, making it very easy to transport from one room to the next.

The Hot+Cool is constructed from tough acrylontride butadiene styrene (ABS), a thermoplastic that is used in police riot helmets and which has good shock-absorbing properties.

There are now more than 240 patents secured for the device, with 170 more pending worldwide.


Dyson Hot+Cool

I have to admit I was quite taken by the machine. While I love seeing advances in computing, I often feel technology companies often fall over one another trying to come up with the next shiniest device and feature and forget basic human necessities.

I think the Dyson Hot+Cool meets this challenge admirably, coming up with a device that is ideal for a variable climate. It is slick to look at, is incredibly useful and manages to be stylish and discreet at the same time.

There are so many positives, however, there has to be one negative. The device  is by no means cheap: starting at €399.99. Then again, producing something of this calibre and quality isn’t easy and businesses do have to make a margin. Like most new technologies, it will be a matter of time before it becomes the universal standard, but already I sense this is a world-changer. A trail has been truly blazed.

The Dyson Hot+Cool comes in nickel/nickel, iron/blue, black/nickel and white/silver colour configurations.

The new fan heater is available exclusively in nickel colour at Brown Thomas up until this Thursday and will be available from a variety of electrical retailers thereafter.

John Kennedy is a journalist who served as editor of Silicon Republic for 17 years