Dyson Pure Cool Review – A stunning looking air purifier but how does it compare?

Dyson Pure Cool – Fabulous air purifier, clever marketing or a bit of both?

Dyson have made a move into the air purification market with their new Pure Cool range of air purifiers. On the face of things the two models, the Pure Cool Link Stand and Pure Cool Link Tower seem to have all the bases covered. They employ Hepa filters to remove airborne pollutants and they also have a layer of carbon to remove odours and VOC’s ( volatile organic compounds ). They also have the ability to act as a cooling fan. On the face of it then, despite the huge price tag, these units seem to do it all. Taking the price to one side for a moment, based upon all of the marketing headlines it is difficult to see why anyone could not be tempted choose a Dyson air purifier right?

There is no doubting Dysons credentials in the design and build of vacuums and hand dryers, and decades of refinement and development coupled with a tenacious faith in what they are doing have quite rightly taken them to the very pinnacle of those marketplaces. So when they bring out a totally new product it is only natural to sit up and take notice. Their stunning designs simply demand attention and the performance claims are considerable, so we took it upon ourselves to look a lot more closely at the technology inside the Pure Cool models to see how they compare with similarly priced air purifiers already at the top of their game.

Firstly lets look at the most important factor in any air purifier- the filter itself.
Like most high end air purifiers, the new Dyson range utilises a Hepa filter to trap airborne particles as small 0.3 to 0.1 microns ( 1 micron is equal to one millions of a metre). Whether or not the Hepa filter inside the new Dyson can trap these particles is not in question, the real question we were wondering was how many of them will it actually trap when the machine is in use?

When is a simple tea bag as good as a genuine Hepa filter?
You see, even a basic tea bag is capable of trapping some of these the tiny airborne particles, but how many particles it would trap would depend upon the speed at which the air is being pulled through it. For instance, if you were to gently blow air through a tea bag it would trap some truly sub micronic particles just like a Hepa filter. However, if you were to force the same air through the same bag at a much higher speed, for instance with a compressed air gun, it probably wouldn’t trap any small particles at all. This point is where most high end air purifiers excel dramatically compared to less well engineered counterparts. For an air purifier to genuinely trap large amounts of airborne pollutants the speed at which the fan pulls the air through the filter is absolutely crucial. This is what is known in the industry as ‘media velocity’. The velocity at which the air travels through the filter has to be controlled perfectly to ensure that the maximum amount of particles are trapped. Too fast and many of the pollutants fly straight through unfiltered. Too slow and the purifier is not reaching the farthest corners of your room quickly enough to be of any use at all.

So how can you properly compare air purifier performance before you shell out your hard earned cash?
All of the world’s most well respected air purifier brands have the media velocity tested and certified by an official body known as AHAM ( The Association of Home Appliance Manufacturers), who test and publish the actual figures achieved by each individual air purifier and list them as an easy to compare CADR (Clean Air Delivery Rate ) figure for each machine. As a general rule a higher CADR rating means better air cleaning effectiveness in a given room size. The best air purifiers will provide around 5 full air changes every hour in their given room capacity.

How do the new Dyson Pure Cool units fare against existing top brands of a similar price range?
Dysons new air purifiers are priced from £399 to £499 pitching them firmly at the higher end of the market against high profile heavyweights in this field like the Blueair 405,  and 480i but despite the hefty price tag, we were unable to find any officially certified AHAM ratings for CADR in any of their promotional material. This information is key to be able to draw a genuine comparison and to know if their machines are effective air purifiers in the truest sense of the words.

So is the Pure Cool range just a stunning looking fan, with a little bit of air purification thrown in for good measure?
One thing the Dyson does have is a very high airflow (not to be confused with CADR above) , in fact this is one thing the promotional material does make very clear. It is natural that for the unit to perform well as a cooling fan it would need to be capable of throwing out a lot of air. But as we have already explained above, moving a lot of air through a small filter too fast drastically reduces its ability to hold onto these tiny particles. Without the benefit of having an independently certified CADR figure we have to wonder if the Pure Cool units are fans first and foremost or are they genuinely effective as air purifiers? ie Just how many of those allergens they can remove are actually removing when the units are in full blown operation?

The image below taken from Dysons own material seems to suggest that the unit is only actually filtering a small portion of the air it blows out. If we read the graphic correctly, it seems to illustrate only 1/15th of the air the Pure Cool provides actually goes through the Hepa filter ( indicated by the small blue arrow at the bottom of the image).


How do the noise levels compare to similar priced equipment?
It is very difficult to move a lot of air, very quietly. Manufacturers have struggled with this problem for decades. The perfect air purifier would be tiny, shift vast quantities of air and be totally silent. That combination simply does not exist. However, it is possible through good design to make an purifier powerful and extremely quiet. Dyson advertise the fact that their new units have been awarded the Quiet Mark by the Noise Abatement Society. This could give the immediate impression to a potential customer that the Dyson models are naturally more quiet than similar machines which do not carry that certification. This is not the necessarily the case however. Many manufacturers simply do not subject their equipment to this type of scheme as their factual decibel ratings are already clearly stated on their promotional material and speak for themselves. Incidentally we could not find any actual quoted dB (decibel) ratings for the Dyson air purifiers on their own promotional literature, however after a bit of searching on the internet we were able to find an article whereby the actual noise levels were recorded and published by a third party reviewer and we have listed these below. Obviously these figures are unofficial and if in doubt  the best option would be to telephone Dyson themselves and ask for their official figures. We have also listed the decibel ratings of some other very popular air purifiers which choose not to subscribe to the ‘Quiet Mark’ for comparison. Noise is very subjective though, so we are not suggesting the Dyson is too loud, just that it appears to be louder than some of the most popular units already available in the market place.

Dyson Pure Cool Link Tower £499 : Decibel Ratings 54 to 81
Blueair 405 £499.00 : Decibel Ratings 32 to 52
Sense+ with Wi-fi £435.00 : Decibel Ratings  29 to 50

What about its ability to remove odours and chemicals?
The removal of chemicals ( VOC’s ) and odours is not handled by the Hepa filter, these are gases, and therefore are too small to be trapped in the Hepa filter. Gases have to be adsorbed, and this is where the Dyson’s carbon filter comes into play. The Dyson does have a small carbon filter and can therefore remove some chemicals, fumes and odours. However, any air purifiers ability to remove these significantly is dictated by two things. Firstly the amount of carbon in the filter – often referred to as ‘carbon weight’ and secondly the speed at which the offending chemicals are passed through the carbon – this is known as ‘dwell time’. A longer dwell time means the carbon filter has more time to adsorb a greater number of chemicals and odours. A dwell time that is too short means many of the chemicals and odours pass through the carbon unhindered. To achieve a longer dwell time, top manufacturers use as much carbon as possible in their air purifiers. Being a fairly small filter, the Dyson seems to naturally have a lot less space inside for carbon than some of the more well established brands which often pack in as much as a full Kilogram or more. The actual weight of carbon inside the Pure Cool range was not visible on our promotional material and therefore it is difficult to draw a fair comparison, however if you take into account that the whole air purifier weighs just over 3kg in total, including the motor, hepa filter and actual body of the machine, it is difficult to see how the carbon weight can be substantial enough to provide a particularly long dwell time. Compare that figure with specialist air purifiers which regularly weigh 15Kg or more and you can begin to see the disparity. We will update this area when more factual information has been provided.

In Summary, should you buy one?
There is no doubting that the Dyson Pure Cool is a really nice looking machine and it can also remove airborne pollutants to some degree. But in our opinion it cannot compare with established manufacturers in this field. If you are looking for a really nice fan , with a bit of air purification thrown in, then this is probably the best machine for you. However, if you are looking for a genuine air purifier, which actually filters 100% of the air it processes, then there are machines out there that offer better value for money. As always, the choice is yours. If you would like advice on choosing the best air purifier for your own needs please feel free to call our offices any time Monday to Friday , we are always delighted to talk to our customers.

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