Vacuum cleaner blew up!

[JP]

Miele cat and dog.

Miele constantly get recommended by Which. I got one after many recs on NG consumer uk discounts and bargains. Superbly engineered, bought GF one too. They are the dogs bs.

[Jim Scott]

[dmc]

My parents bought one of these - nice but the "bag full" sensor seems rather sensitive (in that it nearly always claims the bag is full...)

Have they got a duff one or are they all like this?

Darren

[Jim Scott]

Finally got to the library and 'Which'. Yer right. Miele does come out top followed by Bosch.

Plus all uprights are worse than cylinders. Dyson are the best uprights but keep breaking. The new hoover 'The One' is worse then a brush and should not be bought under any circumstances.

No mention of 'Henry' anywhere.

[Andrew Gabriel]

That measure is rather meaningless. The measurement accepted by the industry is "suction power" as defined in IEC Standard 60312. There is however a recognised problem with this measurement. Bagged cleaners are all measured with new empty bags, which is not at all representitive of their performance other than for the first few seconds. Actual performance during most use is much lower (there's an initial rapid drop and then a steady decline), and a representitve figure is to half the quoted figure. Another problem is the figure fails to take into account how effective a bag is. Cloth bags generally don't drop off as fast as paper bags, because they chuck much more of the dust out in the air exhaust, so it doesn't block them.

For a cyclone cleaner, the "suction power" doesn't significantly drop off. Instead, what happens as they get near full is that the cyclone stops filtering as well. If they get over-full preventing the cyclone operating, they then fall back to operating as a filtered vacuum cleaner using the post-cyclone filters.

So the "suction power" figures are quite heavily biased to favour bagged cleaners.

280 airwatts

Numatic don't quote "suction power" figures (from which you might wonder if they aren't prowd of theirs). A top end bagged cleaner is ~400 airwatts with a new bag, 200 airwatts after a few seconds of use (better for cloth bags, but that's because they're chucking all the finer dust out in the air exhaust), and probably somewhere well under 100 airwatts when bag is getting full, or if you have sucked up any fine dust which has been trapped in the cleaner.

One tip with a bagged cleaner -- If you are going to suck up any fine dust (like plaster dust), do not empty the bag first. The household dust already in the bag will act as a much larger area filter for the finer dust, delaying it blocking the bag pores. Conversely, a cyclone cleaner will work better if you empty it first, and empty it again before it gets full.

In theory, cyclone cleaners should be clear winners. The extracted dust is removed from the air path whereas with a bag/cloth filter, it is clearly trapped directly in the air path. What has held cyclones back is that they work best when they are dustbin sized and upwards. Getting one to work in something the size of a portable domestic vacuum cleaner is a challenge, although Dyson seem to have largely mastered it.

[JP]

nor should a Dyson, constantly slammed in NG I mentioned.

[Matt]

Thanks for that but "suction power" (how the hell did that get adopted as an IEC standard!) is *precisely* why I concentrated on what to my mind really matters, - the air volume at the nozzle and the pressure, these taken both in the as new state and in an aged state after passing a certain volume of air laden with a specified mass of dust. Combine this with the maximum size of particulate at the air exit and the mass of dust retained by the machine and you don't need anything else to know what's better. All the parameters are measurable and you'd only need some dust and carpet - to IEC/ISO standard of course :-)

I use a Numatic in the workshop and a Dyson in the house but they stay where they belong. I've found the Numatic is less than useless for normal household use as despite having a newish bag the dust it passes is appalling - but its fine on wood chips and swarf. The Dyson which would quickly get knackered in the workshop is perfect in the house

"airwatts" would have James Watt turning in his grave

[Matt]

You see loads of them down the council dump but I'd hazard a guess that the vast majority are simple blockages that the brain dead users fail to clear because they never read the manual. I've seen pikeys eyes light up at the sight and watched them cart them off by the car load - probably resurrecting them and selling them for a good profit down the car boots.

My parents have an original DC01 - 12 years old this year, its had half a dozen belts and recently the mains cable fatigued where it enters the strain relief grommet - but apart from that its been faultless. It gets used (make that abused!) every day - previous cleaners from all the usual suspects have lasted 2-3 years

I'd not trust anything Which said though - at times they are about as believable as a Dixons salesman.

[Andrew Gabriel]

That's what "suction power" is -- the vacuum pressure multiplied by the air flow. Neither the vacuum nor the airflow are meaningful by themselves -- a vacuum pump and a large desk fan would have better individual ratings than a vacuum cleaner, but are useless at cleaning floors.

As I said before, unfortunately the standard fails to take into account the rapid drop off of bagged cleaners.

Well, there's also a "pick-up performance" measurement, which includes a measurement of the effectiveness of the pick-up head and brush bar if relevant.

[JP]

They maybe using a far higher power setting than is actually needed. I've only once used the 1600 setting, for the carpet, Usually the 1300 with the turbo brush is fine. It needs only 600 or 900 for the smaller tools. I've never used the 2000 setting, but I've noticed if you do wick the power too far the bag full sensor can move across.

[Set Square]

By all accounts, Dyson can make them *work* - but not work *reliably*!

[Set Square]

Presumably the distance a particle of dust travels in the cyclone before being deposited is measured in Air Miles?

[Bob Eager]

Well (much as I hate to agree with whoever said it (if it was 'huge')), that's why Which is not always a good thing to rely on. Useful for information sometimes, though..

[david lang]

Not off hand - but trust me :-)

Dave

[david lang]

In practice you cant have vacuum pressure and airflow at the same time.

In actual application it's airflow that's important, not vacuum and this varies with the 'final aperture' size. Essentially a 32mm hose gives more suction/less airflow than a 36mm hose. Using two motors in parrallel leaves the suction the same but nearly doubles airflow - which is why twin motor vacs pick up better.

Vacuum pumps are actually used to clean floors - some American manufacturers of carpet cleaning machines, usually truck mounted, use vacuum pumps rather than vacuum turbines to achieve better water recovery rates

Depends on the filter and if it can easily be cleaned or not.

Dave

[david lang]

All too true. I know a guy who runs the largest vac repair shop in the south east. He has a room full of dead Dysons and loves them to bits - he makes a load of money repairing them and selling spare parts.

Dave

[Matt]

Don't, whatever you do, ever consider flying. Go by bus instead, the physics are far less complicated.

[Andy Luckman (AJL Electronics)]

Overpriced I would agree with, but only because of the MLM type of organisation. The rest of your comment I would seriously disagree with. The performance is startling, reliability is excellent and it is only heavy if not adjusted correctly. There are many 20+ year old machines still working perfectly. I have one 25 years old and it is used for workshop mess as well as more domestic duties.

[Ian Stirling]

As the other poster has suggested, real physics are more complex :)

Basically, pressure differences cause airflow. In the case of an absolute vacuum, if you have a hole with a vacuum on one side, then the air will enter it at about the speed of sound.

Usually vacuum cleaners don't suck quite so hard.

When you partially obstruct the hose of the vacuum, then if the vacuum inside remains the same, the airflow drops.

Take the insides out of a ballpoint pen, and play with obstructing the end with your finger, while sucking.

In practice, the vacuum cleaner pump has a curved performance graph. If you were to plot the pressure drop it's working against with airflow, it starts off at zero pressure drop at the maximum airflow, and drops to zero airflow at some pressure drop at which the pump can't do any more.

[Set Square]

Interestingly, one of the things which Which? said was that Dyson owners, despite reporting poor reliability, liked the thing and had a great sense of loyalty towards it.

Seems to be true, despite what people say about Whitch?!