On 23/08/2014 01:31, Arfa Daily wrote:


"Dave Plowman (News)" wrote in message
...
In article ,
Arfa Daily wrote:
It's likely a pretty inefficient design that requires two horsepower to
lift some dust.

I really don't believe that. We have been making electric motors for 150
years or more and I'm pretty sure - particularly in these days of
'efficiency' - that manufacturers will have striven to get the most
power out of their motors for the least power in.

Why should they 'strive'? They're not paying for the electricity. But
they
are for the motor, so the cheaper, the better.



Because these days, it's seen as expedient for manufacturers to be seen
to be trying to wring every drop of efficiency from their products. You
could use the same argument to ask why the makers of TV sets or fridges
or washing machines or a myriad of other consumer electrical items would
bother to try to make their products more efficient, but they have ...

When was the last time anyone bought a vacuum cleaner based on
efficiency. They are normally bought on power alone, so motors are
designed to burn as much power as possible without overheating.

I'm not convinced the speed the average vacuum cleaner motor/fan runs at
is ideal. More likely just convenient.


Convenient how ? They can design the fan any way that they want and
make the motor run at any speed they want. Do you seriously believe that
they would just pick some arbitrary combination and declare "that'll do
then ... " ?

I guess convenient as in lowest cost motor that will burn the power and
deliver sufficient suction that the average user is content with its
hoovering abilities.

They certainly make enough noise
and get hot.

And that's important because ?

It demonstrates how inefficient they are.

What I would like to see is a rating structure that represents say
suction and flow vs power input.