Dyson Hot + Cool AM04 Heater Review: Stay Warm In Style, For A Price

I recently bought a little Dyson upright vacuum. It's sturdy and well-engineered, performs surprisingly well and is beautifully designed. I love using it. But it wasn't exactly cheap. The Hot + Cool ceramic space heater/fan -– the latest in Dyson's 'air multiplier' range -– carries much the same traits. For some, the Dyson name may be enough to convince your significant other. But others may just be wondering what the heck kind of tech begins to justify the $549 price tag. Let's take a look.

How It Works

Similar to the Dyson Air Multiplier AM02 fan, the Hot + Cool (aka Dyson Hot) pushes air instead of spinning blades. And as Dyson's first heater, we see some new touches.

The base encases a rotating mixed-flow impeller that draws air in and over special ceramic heating stones. The air is then jetted out through thin slots, along the airfoil-shaped ramp (the blue area you see pictured) and out into your room. This process is what Dyson refers to as its ‘Air Multiplier' tech, and this is how the Hot + Cool heats rooms faster and more evenly than traditional space heaters.

What We Liked

The 55cm-tall Hot + Cool definitely has good looks and became a conversation starter when I had friends around. I'll admit I probably fall into the perfect target market: I've started to buy nicer lounge room furniture for my little apartment, but I don't have central heating. As a stylish table-top heater, the Hot + Cool complements the aesthetic of my nesting investments. Sure, that's a bit wanky (and throwing on a jumper will get me to my house deposit faster) but there are other benefits too.

Because the Hot + Cool's heating components don't go beyond 200 degrees Celsius, you won't get that dust burning smell that occurs when other heaters get to around 233C. These heating plates are also internal, so the Hot + Cool could be worth considering over certain blade or element space heaters if you've got pets or kids. The Dyson is also much easier to clean. Other safety features include a base that's bottom-heavy to help avoid tip-overs, and an automatic cut-off feature should a knock actually occur.

The Hot + Cool is certainly easy to use. It can be tilted up or down on its base, and stays in place nicely without clamps even when oscillating from side to side. In fact, the adjustability and precise temperature settings are what had me hooked. You can go from zero (cool-air fan) to 37 degrees, and select up to 10 airflow speeds for your choice of energy efficiency. An included remote control means you don't have to get up, and when not in use, the remote's curved/magnetised design lets it nestle neatly atop the heater.

This is the first portable space heater that I've used with an intelligent self-monitoring thermostat, and I've definitely become spoiled. In my 8 by 5 metre lounge room, I was able to set a target temperature of 22 degrees and get there in about 20 minutes — heat projection for the win!

What We Didn't Like

The thermostat tells the heater to power on and off as your room cools from its target temperature. Unfortunately, it takes a few moments for the heat to kick in again which can lead to a chilly surprise if you fall asleep in front of the Hot + Cool (as I've been known to do on my couch).

The heater uses jet engine-like technology, and at full blast, you kind of remember that. As you can see in the video, sound levels do dip dramatically on lower settings. Ultimately, the noise level wasn't so high that it bothered me (I just turned up my TV slightly), but you should ask to see/hear it in action before taking one home. This is an area where I'd expect to see future versions improve.

Other minor quibbles: As a fan, the Hot + Cool performs only half the air multiplication of the dedicated Dyson cooling fan (6x to 15x); the attached 1.8m power cord could be a tad longer; and the remote control's battery would be super easy for a child to pop out (and potentially swallow).

Should You Buy It?

As touched upon, the Hot + Cool isn't about simply getting from point A to B; this is about the grand parade in between. You're either in or you're out, so I'll let you answer the price equation for yourself. You can find deals from around $440 for the heater if you look around.

In either grey/blue (pictured) or white/silver, the Hot + Cool looks great, is easy to control and effectively heats small-to-medium sized rooms. It comes with a 2 year guarantee.

There are cheaper, smarter options out there, but I'm sick of lounging with my doona — and a little luxury is nice once in a while. At least that's how I plan to convince my wife. [Dyson Australia]


    "There are cheaper, smarter options out there"
    Listening to the cyclonic noise it makes, you would have been better served by the Cheaper smarter option, me thinks. Way too loud for the price and the 24-30 range is the comfort zone.

    What's range of power draw on these things? How do they compare with traditional strip heater etc?

      Yeah, I can't imagine it would be cheap on electricity either!

    Stop blogging and charge that Kindle!

    Could you recommend some alternatives to the Dyson Hot + Cool? I've never seen any like it but it would be interesting to see some feature and price comparisons of similar products if they exist.

    I bought one of these a few weeks ago and still haven't been able to make up my mind as to if it was worth it or not. The biggest problem I've got with it is the noise, anything above power level 3 is intrusive. Apart from that it seems to do a decent job of warming the room. It's not the type of heater that you can sit in front of and feel the burn, I think it's main aim is to bring the temperature of the room up to a comfortable temperature. I find that I still need to wear a jumper to keep warm. It's rated at 2000W which is about the same as other fan or convection heaters.

    I'd rather save my pennies by walking around in my PJ's, a shower robe and a doona draped over me. Possibly chuffing on a cigar at the same time.

    In the end, if it's rated at 2000 watts, until it get's to the temperature it's set for, it's going to draw 2000 watts of electricity and put out 2 kilowatt hours of heat every hour. Exactly the same performance as a $25 fan heater.
    The only way to beat that equation is with a reverse cycle air conditioner, which actually pumps more heat in from the outside than the amount of power it consumes.

      Untrue, an aircon that can run on a 10amp power circut(2400watts) can produce 3500 watts of heating output. The amount out power that is drawn from the plug has no relation to they heat that is produced.

      Your example is like saying that if two cars have the same size fuel tank, they will have the same economy.

        PS - I think you need to review your maths - or check out the Choice magazine heating & cooling guide: http://www.choice.com.au/reviews-and-tests/household/heating-and-cooling/home-heating/heating-options-for-your-home-buying-guide.aspx
        In Chris' example, a conventional heater will use 2.0kW of electricity to provide a rated heating capacity of 2.0kW of heat. This means that the heater has a nominal efficiency factor of 1.0 (i.e. 2.0kW heat / 2.0kW electricity).
        In your example, you went on to describe a (very inefficient) reverse cycle air-conditioning system that was rated to use 2.4kW of electricity to provide a nominal heating capacity of 3.5kW of heat. This means that the A/C has a nominal efficiency factor of 1.45 (i.e. 3.5kW heat / 2.4W electricity).
        Even if you had to use that horrible, inefficient system you described, the A/C's efficiency factor of 1.45 is still superior to the conventional heater's factor of 1.0. Modern A/C's have efficiency factors closer to 3 or 4 (at least in the 3.5kW heating range).

        However, I disagree that a reverse cycle A/C is the "best" solution in itself - A/C should only be considered as a stop-gap in the event you have lots of guests over, or if temperatures become extremely hot or cold. It is still better in the long run to re-examine and optimse the way buildings are weather-sealed & insulated - and how the sun can be used in winter, and avoided in summer.

    The trick with any room heater is how it handles convection (i.e. hot air rising straight up into the ceiling before eventually coming down to heat your head - and much later, the rest of your body).
    I don't think the Dyson Hot has been designed with any consideration to heating or convection - it's still designed like a normal fan - which is fine for cooling (i.e. evaporating sweat on your body), but not so for heating.
    For one, the heated air will rise as soon as it leaves the fan - hence, if it's pointed at your body (as it normally does for cooling), most of the heated air will be diverted upwards.
    Another, is that blowing hot air directly at someone is actually quite an unpleasant way to heat them up- it's too dry on the skin.
    One way to offset this is to set the fan to direct the heated air downwards as it leaves the fan - so that the heated air will then travel up towards the user (insteading of going straight to their head or the ceiling).
    Still - I'd rather spend the money you did on more clothes (socks & beanies, thermal undergarments), multiple heaters (if you need to heat the space if you have kids or company visiting), electric blankets, and finding ways to insulate the living area to reduce unnecessary heat loss (seal windows, close curtains, insulate floors, etc.)

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