Kettles with concealed elements - are they all so noisy?

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Phil Addison

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Dec 8, 2006, 11:32:40 AM12/8/06
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SWIMBO bought a shiny new steel kettle, and now we can't listen to the
kitchen radio when its on (the kettle that is!!) because it makes such a
vigorous 'kettling' racket, and not just when it's near boiling. Last
weekend I talked to a guy in our independent appliance retailer and he
said they are all like that these days, its due to the trendy new
'concealed element' design.

The concealed element 'feature' is where the element is embedded in the
flat bottom of the kettle, rather than being the conventional 'bent rod'
style immersed in the water. I think the noise is due to the large flat
base acting as a kind of sounding board.

On a quick look it seems as if this style of kettle is all that's
available these days. Has anyone else come across this problem? Any
recommendations for a good quiet cordless kettle?

Phil
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Richard

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Dec 8, 2006, 11:46:57 AM12/8/06
to

Phil Addison wrote:
> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes such a
> vigorous 'kettling' racket, and not just when it's near boiling. Last
> weekend I talked to a guy in our independent appliance retailer and he
> said they are all like that these days, its due to the trendy new
> 'concealed element' design.
>
> The concealed element 'feature' is where the element is embedded in the
> flat bottom of the kettle, rather than being the conventional 'bent rod'
> style immersed in the water. I think the noise is due to the large flat
> base acting as a kind of sounding board.
>
> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?
>
> Phil


I thought it was just our model, Ours is so loud you struggle to hear
the tv in the lounge, its like a bloody jet engine, and it wasnt a
cheap one either. I think the faster the water is boiled the greater
the noise also, ie a 2kw will be noiser than a 1kw

Andy Wade

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Dec 8, 2006, 12:10:34 PM12/8/06
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Richard wrote:

> I thought it was just our model, Ours is so loud you struggle to hear
> the tv in the lounge, its like a bloody jet engine, and it wasnt a
> cheap one either. I think the faster the water is boiled the greater
> the noise also,

Yes. Also plastic-bodied ones are much quieter than metal-bodied ones, IME.

--
Andy

Anna Pinnion

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Dec 8, 2006, 12:13:17 PM12/8/06
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"Phil Addison" <phi...@bigNOSPAMfoot.com> wrote in message
news:153jn2lhnm0ivg6u8...@4ax.com...

We used to be in the same boat, got through 3 of these in virtually as many
years, at 30 quid a pop not cheap.
The reason they are so noisy is the heated baseplate acts as a large
radiator for the sound of water instantly expanding to water vapour at
various hotspots across the surface.
The reason why they have a crap lifetime is the element itself is not fully
cooled underneath by the water, and gradually vaporises/sublimes over a
period of time until finally the weakest link gives.

We bought an el cheapo 'Cookware' kettle from Argos (£5) with the
conventional fully submerged element about 3.5 years ago.

It's still going strong!


Ian Stirling

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Dec 8, 2006, 1:16:15 PM12/8/06
to
Phil Addison <phi...@bignospamfoot.com> wrote:
> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes such a
> vigorous 'kettling' racket, and not just when it's near boiling. Last
> weekend I talked to a guy in our independent appliance retailer and he
> said they are all like that these days, its due to the trendy new
> 'concealed element' design.

Personally, I have a Russel Hobbs kettle.
Like
http://www.amazon.co.uk/Russell-Hobbs-11403-Montana-Cordless/dp/B0000YW72A/sr=1-16/qid=1165601323/ref=sr_1_16/203-3793610-7145510?ie=UTF8&s=kitchen
but white.

I can just about hear the radio, on at a normal volume next door.
With the radio on next to it at a normal volume, there is no problem
whatsoever.
I suspect it's that steel is more noisy, to some extent.

And personally, I love the concealed element feature.
I typically have around a cupfull of water in the kettle, which it boils
really fast.
It will happily boil half a cup.

Not to mention the topic of the moment - energy saving.

If you boil an extra cup of water 4 times a day, you spend 3 pounds a
year extra, and spend an extra several hours a year waiting on the
kettle.

Alex

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Dec 8, 2006, 1:23:19 PM12/8/06
to
Phil Addison wrote:
> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?

Well my quite cheap "Breville" one from Sainsbury's isn't very loud, and
it has a blue LED in the power switch for added coolness ;)

Alex

Guy King

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Dec 8, 2006, 1:34:29 PM12/8/06
to
The message <45799d1c$0$8721$ed26...@ptn-nntp-reader02.plus.net>
from "Anna Pinnion" <a...@zorbo.net> contains these words:

> We bought an el cheapo 'Cookware' kettle from Argos (£5) with the
> conventional fully submerged element about 3.5 years ago.

> It's still going strong!

Mum's got a Russel Hobbs non-jug kettle that must be 20 years old at
least, and it's still on the original element. Needs descaling
frequently 'cos her water comes from the North Downs chalk.

--
Skipweasel
Pay no attention to that man behind the curtain.

Grimly Curmudgeon

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Dec 8, 2006, 1:10:55 PM12/8/06
to
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Phil Addison
<phi...@bigNOSPAMfoot.com> saying something like:

>On a quick look it seems as if this style of kettle is all that's
>available these days. Has anyone else come across this problem? Any
>recommendations for a good quiet cordless kettle?

Stop being so pikey and use the living room.
--

Dave

Phil L

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Dec 8, 2006, 2:24:44 PM12/8/06
to
Phil Addison wrote:
> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes
> such a vigorous 'kettling' racket, and not just when it's near
> boiling. Last weekend I talked to a guy in our independent appliance
> retailer and he said they are all like that these days, its due to
> the trendy new 'concealed element' design.
>
> The concealed element 'feature' is where the element is embedded in
> the flat bottom of the kettle, rather than being the conventional
> 'bent rod' style immersed in the water. I think the noise is due to
> the large flat base acting as a kind of sounding board.
>
> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?

Why would anyone purchase something like this? - I mean, what's the point? -
if the design hasn't been improved (and it sounds like it most definitely
hasn't) why change just for the sake of changing? - are they supposed to be
energy saving?

We buy cordless kettles from supermarkets, the last one was p'chased from
Asda 3.5 yrs ago and set us back the princely sum of £6, it still works but
there's a small leak at the window where the water level is shown, I use it
for work, the new one cost a fiver from Morrisons, had a plug on it and
everything.


Ian Stirling

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Dec 8, 2006, 2:28:53 PM12/8/06
to
Phil L <neverc...@hotmail.com> wrote:
> Phil Addison wrote:
>> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
>> kitchen radio when its on (the kettle that is!!) because it makes
>> such a vigorous 'kettling' racket, and not just when it's near
>> boiling. Last weekend I talked to a guy in our independent appliance
>> retailer and he said they are all like that these days, its due to
>> the trendy new 'concealed element' design.
>>
>> The concealed element 'feature' is where the element is embedded in
>> the flat bottom of the kettle, rather than being the conventional
>> 'bent rod' style immersed in the water. I think the noise is due to
>> the large flat base acting as a kind of sounding board.
>>
>> On a quick look it seems as if this style of kettle is all that's
>> available these days. Has anyone else come across this problem? Any
>> recommendations for a good quiet cordless kettle?
>
> Why would anyone purchase something like this? - I mean, what's the point? -
> if the design hasn't been improved (and it sounds like it most definitely
> hasn't) why change just for the sake of changing? - are they supposed to be
> energy saving?

Less water in them not only means energy saving, it means they boil
faster, which is good.

Owain

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Dec 8, 2006, 11:54:54 AM12/8/06
to
Phil Addison wrote:
> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes such a
> vigorous 'kettling' racket, and not just when it's near boiling. Last
> weekend I talked to a guy in our independent appliance retailer and he
> said they are all like that these days, its due to the trendy new
> 'concealed element' design.

They did that in the 1930s, in fact I have a book showing how to make an
electric kettle from an ordinary kettle, some element wire, scrap
copper, etc.

> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?

£8 from Tesco.

Owain

The Central Authority

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Dec 8, 2006, 3:12:28 PM12/8/06
to
On Fri, 08 Dec 2006 16:32:40 GMT, Phil Addison
<phi...@bigNOSPAMfoot.com> wrote:

>SWIMBO bought a shiny new steel kettle, and now we can't listen to the
>kitchen radio when its on

As an aside I'd note that the kitchen radio we bought turned out to be
a lost cause because every *thing* and every *activity* in the kitchen
drowned it out.

>(the kettle that is!!) because it makes such a
>vigorous 'kettling' racket, and not just when it's near boiling.

That IIRC was the problem with original Goblin "Teasmades".

About 25 mins before the appointed hour it made a very loud "click",
(like a mousetrap) and then made kettling noises for the remaining 25
mins until the tea was ready, so you didn't wake to a fresh cup of
tea, you woke to all this infernal racket.

ISTR old fashioned kettles used to go quiet just before starting to
boil vigorously. Presumably once the air has been boiled out of the
region near the element it goes quiet. It's likely the new order
kettles with large surface area heating surfaces just heat the water
too uniformly and gradually prolonging the agony.

Doubtless it's due to Air/O2 bubbles forming and collapsing. But AIUI
water without dissolved air makes poor tea, (I don't partake myself),
so can't suggest anything. :-(

DG

meow...@care2.com

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Dec 8, 2006, 3:52:22 PM12/8/06
to
Phil Addison wrote:

> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes such a
> vigorous 'kettling' racket, and not just when it's near boiling. Last
> weekend I talked to a guy in our independent appliance retailer and he
> said they are all like that these days, its due to the trendy new
> 'concealed element' design.
>
> The concealed element 'feature' is where the element is embedded in the
> flat bottom of the kettle, rather than being the conventional 'bent rod'
> style immersed in the water. I think the noise is due to the large flat
> base acting as a kind of sounding board.
>
> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?
>
> Phil

the only option not yet mentioned is to reduce the kettle power. A
series impedance will do that. A diode would roughly halve power use,
you'd want a 1kv 12A rated diode for long term reliability.


NT

meow...@care2.com

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Dec 8, 2006, 3:54:11 PM12/8/06
to
Phil Addison wrote:

> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes such a
> vigorous 'kettling' racket, and not just when it's near boiling. Last
> weekend I talked to a guy in our independent appliance retailer and he
> said they are all like that these days, its due to the trendy new
> 'concealed element' design.
>
> The concealed element 'feature' is where the element is embedded in the
> flat bottom of the kettle, rather than being the conventional 'bent rod'
> style immersed in the water. I think the noise is due to the large flat
> base acting as a kind of sounding board.
>
> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?
>
> Phil

the only option not yet mentioned is to reduce the kettle power. A


series impedance will do that. A diode would roughly halve power use,
you'd want a 1kv 12A rated diode for long term reliability.

The other option is acoustic damping, which is quite doable with double
walled kettles. That way you could get all your wants, but would have
to mess with it to get it there.


NT

meow...@care2.com

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Dec 8, 2006, 3:55:44 PM12/8/06
to
Phil Addison wrote:

> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes such a
> vigorous 'kettling' racket, and not just when it's near boiling. Last
> weekend I talked to a guy in our independent appliance retailer and he
> said they are all like that these days, its due to the trendy new
> 'concealed element' design.
>
> The concealed element 'feature' is where the element is embedded in the
> flat bottom of the kettle, rather than being the conventional 'bent rod'
> style immersed in the water. I think the noise is due to the large flat
> base acting as a kind of sounding board.
>
> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?
>
> Phil

the only option not yet mentioned is to reduce the kettle power. A


series impedance will do that. A diode would roughly halve power use,
you'd want a 1kv 12A rated diode for long term reliability.

The other option is acoustic damping, which is quite doable with some


kettles. That way you could get all your wants, but would have to mess

with it to get it there. First thought for that would be an assortment
of large steel nuts sitting on blobs of high temp silicone, anywhere
and everywhere they could go without being visible, ie underneath where
most needed, plus some more in the handle area, and whatever you can
get into the sit-on base.


NT

Guy King

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Dec 8, 2006, 3:49:55 PM12/8/06
to
The message <drfjn29r6a7r7m0fp...@4ax.com>
from The Central Authority <wibble...@miniac.demon.co.uk> contains
these words:

> ISTR old fashioned kettles used to go quiet just before starting to
> boil vigorously. Presumably once the air has been boiled out of the
> region near the element it goes quiet. It's likely the new order
> kettles with large surface area heating surfaces just heat the water
> too uniformly and gradually prolonging the agony.

> Doubtless it's due to Air/O2 bubbles forming and collapsing.

Not quite. The noise before it comes to the boil is steam bubbles
forming and collapsing - the water around the element exceeds the
boiling point but the bulk of the water in the kettle doesn't so the
bubble collapses immediately. The implosion is quite violent, it's the
same idea as an ultrasonic cleaner.

As the bulk of the water nears boiling point it's much closer to the
temperature of the steam in the bubbles, so heat transfer across the
bubble's surface is a lot slower. The bubbles either collapse more
gently, or they fail to collapse at all and break the surface. Either is
a lot quieter than the decrepitation of hot bubbles in cool water.

Of course, more heat is lost when the bubbles break the surface, the
escaping steam carries away heat very efficiently, and this is why water
doesn't exceed its boiling point at a given pressure - the faster you
put heat in the faster the steam carries the heat away. Until of course
it's all gone. Then you need a new element.

Brian Sharrock

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Dec 8, 2006, 4:07:09 PM12/8/06
to

"Phil L" <neverc...@hotmail.com> wrote in message
news:0_ieh.13698$k74....@text.news.blueyonder.co.uk...

snip

>
> We buy cordless kettles from supermarkets, the last one was p'chased from

> Asda 3.5 yrs ago and set us back the princely sum of Ł6, it still works

> but there's a small leak at the window where the water level is shown,

They all seem to leak at the junction between dissimilair materials !
I've lost count of the kettles we've jinked because I get fed up with
mopping water from around the base {The 'cordless' connector gubbins seems
quite 'safe' with its turret connector}.
Finally purchase a metal body, concealed element, jug kettle without any
window!

> I use it for work, the new one cost a fiver from Morrisons, had a plug on
> it and everything.

Everything is supposed to have a plug !
The populace can't be trusted to fit a plug!
What'd'ye thinks this is? D-I-Y ?

--

Brian


MikeH

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Dec 8, 2006, 4:07:07 PM12/8/06
to
Phil Addison wrote:
> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes such a
> vigorous 'kettling' racket, and not just when it's near boiling. Last
> weekend I talked to a guy in our independent appliance retailer and he
> said they are all like that these days, its due to the trendy new
> 'concealed element' design.
>
> The concealed element 'feature' is where the element is embedded in the
> flat bottom of the kettle, rather than being the conventional 'bent rod'
> style immersed in the water. I think the noise is due to the large flat
> base acting as a kind of sounding board.
>
> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?
>
> Phil


I've tried about five diferent makes/models and they all made a hell of
a racket. The water boils locally where it contacts the heat source,
makes a load of tiny steam bubbles, and this results in the noise. I
think the old non-concealed elements made a bit less noise, and they do
tend to quieten just before the water starts to properly boil. I've
also noticed that swirling the water around as it's being heated
results in a quieter boil - maybe because the agitation cuts down the
creation of steam bubbles on the element. Maybe a built-in impeller to
stir the water would reduce the problem? Anyone fancy making a
prototype? I'd be happy to pay a premium for a quiet kettle. :-)

Mike

Dave Liquorice

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Dec 8, 2006, 4:11:48 PM12/8/06
to
On 8 Dec 2006 08:46:57 -0800, Richard wrote:

> I think the faster the water is boiled the greater the noise also, ie a
> 2kw will be noiser than a 1kw

The "rapid boil" kettles are 3kW and are noisey but you don't have to
wait long for it to boil. B-) The urn wasn't up to temperature on an OB
the other day and the standby kettle was in use, I thought the kettle was
bust as it was taking so long...

--
Cheers new...@howhill.com
Dave. pam is missing e-mail

R.P.McMurphy

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Dec 8, 2006, 5:41:42 PM12/8/06
to

"Guy King" <guy....@zetnet.co.uk> wrote in message
news:3130303034323...@zetnet.co.uk...

Nice explanation! Must be the same reason why a milk frother is so noisy
too!

Steve


Guy King

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Dec 8, 2006, 6:36:01 PM12/8/06
to
The message <4579ea28$0$8734$ed26...@ptn-nntp-reader02.plus.net>
from "R.P.McMurphy" <r.p.mcmu...@ntlworld.com> contains these words:

> Nice explanation! Must be the same reason why a milk frother is so noisy
> too!

Certainly is.

What I can't find is the explanation for why the sound of tapping a
spoon on the bottom of a fresh poured drink rises in pitch as you
continue to tap. I saw one a while ago, but I can't remember the
details. Something about microbubbles changing the speed of sound in the
liquid but that doesn't always seem to fit what's happening.

Ian Stirling

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Dec 8, 2006, 8:03:17 PM12/8/06
to

The Russel Hobbs kettle I mention otherwheres in the thread has a
vertical pole inside, which seems to effectively cause the water to
tumble, however, it only works when the kettle has around half a litre
of water in or more.

John Rumm

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Dec 8, 2006, 8:19:15 PM12/8/06
to
Guy King wrote:

> What I can't find is the explanation for why the sound of tapping a
> spoon on the bottom of a fresh poured drink rises in pitch as you
> continue to tap. I saw one a while ago, but I can't remember the
> details. Something about microbubbles changing the speed of sound in the
> liquid but that doesn't always seem to fit what's happening.

I have seen a number of debates on this subject none that claim to be
conclusive.

The one that interested me was why the pitch rose as you stirred a
powder like drinking chocolate into hot milk or water. The most
noticeable one I found was stirring honey into hot milk - the pitch
rises as you stir, but the falls again if you pause and restart -
probably as the honey does not emulsify in the liquid and some starts to
settle out again.

My best guess for the cause is that as you hit the cup you cause it to
ring. It will ring at its "natural" resonant frequency. Control theory
tells us that as you add damping to a system you also cause the
frequency it will resonate at to move away from the natural frequency. I
guess that is what is happening here. As the powder dissolves into the
liquid it alters its viscosity and hence the damping effect it has on
the ring and the more pitch shift.

Any other explanations you can think of?


--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

Chris J Dixon

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Dec 9, 2006, 3:44:53 AM12/9/06
to
John Rumm wrote:

>The one that interested me was why the pitch rose as you stirred a
>powder like drinking chocolate into hot milk or water. The most
>noticeable one I found was stirring honey into hot milk - the pitch
>rises as you stir, but the falls again if you pause and restart -
>probably as the honey does not emulsify in the liquid and some starts to
>settle out again.
>
>My best guess for the cause is that as you hit the cup you cause it to
>ring. It will ring at its "natural" resonant frequency. Control theory
>tells us that as you add damping to a system you also cause the
>frequency it will resonate at to move away from the natural frequency. I
>guess that is what is happening here. As the powder dissolves into the
>liquid it alters its viscosity and hence the damping effect it has on
>the ring and the more pitch shift.
>
>Any other explanations you can think of?

The stirring causes the liquid level to rise at the edges and
thus increase the damping of the cup. Let it settle and it is
back as it was. Repeat at will.

Chris
--
Chris J Dixon Nottingham UK
ch...@cdixon.me.uk

Have dancing shoes, will ceilidh.

Helen Deborah Vecht

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Dec 9, 2006, 6:07:19 AM12/9/06
to
"Anna Pinnion" <a...@zorbo.net>typed


> We bought an el cheapo 'Cookware' kettle from Argos (Ł5) with the

> conventional fully submerged element about 3.5 years ago.

> It's still going strong!

I bought a reasonable Russell Hobbs from John Lewis 30 years ago; it's
still going strong...

(The concealed element kettle I bought in 1999 failed a while ago...)

--
Helen D. Vecht: helen...@zetnet.co.uk
Edgware.

Andrew McKay

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Dec 9, 2006, 6:23:09 AM12/9/06
to
Helen Deborah Vecht wrote:
> I bought a reasonable Russell Hobbs from John Lewis 30 years ago; it's
> still going strong...

I remember buying one of those too, around that time. It was for our
small office which didn't have a coffee machine (so the kettle got a
fair amount of use). Worked flawlessly in all the years we were there.

We now use cheapo electric kettles which we can buy in the local Tesco's
for a fiver. They tend to fail fairly often (maybe once a year or so),
but for that price who cares?

Andrew

--
You probably don't want to reply to my published newsgroup email address
because your email is guaranteed to be treated as spam. If you really do
need to get hold of me use my contact form at http://www.kazmax.co.uk.
an...@kazmax.co.uk is configured as an anti-spam email address.

Guy King

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Dec 9, 2006, 6:21:49 AM12/9/06
to
The message <457a0e99$0$8731$ed26...@ptn-nntp-reader02.plus.net>
from John Rumm <see.my.s...@nowhere.null> contains these words:

> Any other explanations you can think of?

Change of speed of sound in the fluid. That should affect the resonance
much as breathing helium affects the pitch of your voice.

Rotation of the fluid in the container. Particularly if the fluid is
rotating faster in the middle the propgation may be more spiral than
radial, so the path is longer giving a longer wavelength. As it slows
down the path shortens and the pitch rises. I really liked this idea
until I tried it. Milk and honey with nutmeg on top to show the flow and
the pitch continued to rise significantly long after any rotation
ceased. Shame 'cos it was quite plausible! It may still play a part in
the early stages though. I need to try it with a stable fluid rather
than a freshly hot one.

What would really help would be having a name for the phenomenon to make
it easier to find other research.

Guy King

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Dec 9, 2006, 6:24:56 AM12/9/06
to
The message <h0tkn2duvcdnl17s2...@4ax.com>
from Chris J Dixon <ch...@cdixon.me.uk> contains these words:

> The stirring causes the liquid level to rise at the edges and
> thus increase the damping of the cup. Let it settle and it is
> back as it was. Repeat at will.

Hmmm, in my experience it isn't repeatable. Only works with a freshly
poured cup, and restirring doesn't let it happen again. And anyway the
pitch continues to rise after rotation has ceased.

I've a feeling it's to do with microbubbles in the liquid that change
the speed of sound until they've all risen to the top. Perhaps I'll try
it with bicarb solution and add a drop of vinegar. If I can make it
repeat each time a drop's stirred in that may show the way.

Guy King

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Dec 9, 2006, 6:28:47 AM12/9/06
to
The message <3130303037363...@zetnet.co.uk>
from Helen Deborah Vecht <helen...@zetnet.co.uk> contains these words:

> (The concealed element kettle I bought in 1999 failed a while ago...)

That one with the lights round the bottom that looked and sounded like a
rocket taking off?

Helen Deborah Vecht

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Dec 9, 2006, 6:50:51 AM12/9/06
to
Guy King <guy....@zetnet.co.uk>typed


> The message <3130303037363...@zetnet.co.uk>
> from Helen Deborah Vecht <helen...@zetnet.co.uk> contains these words:

> > (The concealed element kettle I bought in 1999 failed a while ago...)

> That one with the lights round the bottom that looked and sounded like a
> rocket taking off?

Yup, that's the one. It started leaking and I wouldn't dare mix
electrickery with water.

It was from a set of three gadgets I bought from Tesco; the toasted
sandwich maker let off the magic blue smoke when I toasted the mains
cord, then the kettle leaked. I still use the toaster, but its pop-up
springs are rather weak.

Brian L Johnson

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Dec 9, 2006, 8:32:03 AM12/9/06
to
Guy King wrote

> What I can't find is the explanation for why the sound of tapping a
> spoon on the bottom of a fresh poured drink rises in pitch as you
> continue to tap. I saw one a while ago, but I can't remember the
> details. Something about microbubbles changing the speed of sound in the
> liquid but that doesn't always seem to fit what's happening.
>

When you pour a hot liquid into a (relatively) cool cup, the cup will
expand. If you're stirring it, it will be ringing like a bell and a
bigger bell means a...

Oh. Oh, well.

--
-blj-

Roger R

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Dec 9, 2006, 9:00:35 AM12/9/06
to

"Phil Addison" <phi...@bigNOSPAMfoot.com> wrote in message
news:153jn2lhnm0ivg6u8...@4ax.com...

> SWIMBO bought a shiny new steel kettle, and now we can't listen to the
> kitchen radio when its on (the kettle that is!!) because it makes such a
> vigorous 'kettling' racket, and not just when it's near boiling. Last
> weekend I talked to a guy in our independent appliance retailer and he
> said they are all like that these days, its due to the trendy new
> 'concealed element' design.
>
> The concealed element 'feature' is where the element is embedded in the
> flat bottom of the kettle, rather than being the conventional 'bent rod'
> style immersed in the water. I think the noise is due to the large flat
> base acting as a kind of sounding board.
>
> On a quick look it seems as if this style of kettle is all that's
> available these days. Has anyone else come across this problem? Any
> recommendations for a good quiet cordless kettle?

Don't know about concealed element types, mine has the normal exposed type.
Hard or soft water appears to make some difference.

The water here is hard and the kettle made a tremendous racket from soon
after getting warm until boiling. As you say the radio could not be heard
above it. Then I started using bottled water and that began to dissolve
the scale, though none could be seen on the element itself except around
where the element is fixed to the vessel. I used a proprietory descaler
to remove all the scale.

Now, using the bottled water it doesn't make any noise at all until just off
boiling, but even then its much less than before. I can hear the radio
again. So I think the noise is made much worse by hardness in the water,
making a very thin - invisible micro scale layer on the element, but why
that should be make the noise worse...? Something to do with the breakdown
of the temporary hardness of the water during boiling perhaps.

Roger R


Andy Wade

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Dec 9, 2006, 9:30:10 AM12/9/06
to
Helen Deborah Vecht wrote:

> I bought a reasonable Russell Hobbs from John Lewis 30 years ago; it's
> still going strong...

OTOH IME a more recent sample of the same make started leaking after
just over one year (DIY fixed) and the switch packed up after a further
6 months (gave up).

R-H are part of the Salton Group now, formerly known as Pifco...

--
Andy

John Rumm

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Dec 9, 2006, 10:55:05 AM12/9/06
to
Chris J Dixon wrote:

>>Any other explanations you can think of?
>
>
> The stirring causes the liquid level to rise at the edges and
> thus increase the damping of the cup. Let it settle and it is
> back as it was. Repeat at will.

That is one suggestion I have seen, along with a suggestion that the
swirling causes the spinning liquid to reduce the amount of exposed cup
height thus altering the resonant frequency of the tuned pipe air column
above the liquid.

I am not convinced by these, because with powders that disolve
completely into the liquid the change in pitch is permenent - letting
things settle does not reverse the pitch change. Also the air column
height is so short that it would represent a quarter wave resonator for
a much higher pitch that you hear in real life.

John Rumm

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Dec 9, 2006, 10:59:22 AM12/9/06
to
Guy King wrote:

> The message <457a0e99$0$8731$ed26...@ptn-nntp-reader02.plus.net>
> from John Rumm <see.my.s...@nowhere.null> contains these words:
>
>
>>Any other explanations you can think of?
>
>
> Change of speed of sound in the fluid. That should affect the resonance
> much as breathing helium affects the pitch of your voice.

Yup - that could certainly be the case... you would probably expect to
detect a pitch change with temperature as well then as the density of
the liquid changes.

> Rotation of the fluid in the container. Particularly if the fluid is

The other problem with rotation based theorys is that I tend to stir
side to side rather than by inducing rotation. You still get the same
effect.

> What would really help would be having a name for the phenomenon to make
> it easier to find other research.

Perhaps there is a PhD thesis waiting to be had here ;-)

John Rumm

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Dec 9, 2006, 11:02:02 AM12/9/06
to
Roger R wrote:

> Now, using the bottled water it doesn't make any noise at all until just off
> boiling, but even then its much less than before. I can hear the radio
> again. So I think the noise is made much worse by hardness in the water,
> making a very thin - invisible micro scale layer on the element, but why
> that should be make the noise worse...? Something to do with the breakdown
> of the temporary hardness of the water during boiling perhaps.

It may be that the scale adds roughness to the surface which acts as a
seed site making it eaiser for cavitation to occur....

Ian Stirling

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Dec 9, 2006, 11:55:35 AM12/9/06
to
Roger R <d-e-c-...@clara.co.uk> wrote:
<snip>

> The water here is hard and the kettle made a tremendous racket from soon
> after getting warm until boiling. As you say the radio could not be heard
> above it. Then I started using bottled water and that began to dissolve
> the scale, though none could be seen on the element itself except around
> where the element is fixed to the vessel. I used a proprietory descaler
> to remove all the scale.
>
> Now, using the bottled water it doesn't make any noise at all until just off
> boiling, but even then its much less than before. I can hear the radio
> again. So I think the noise is made much worse by hardness in the water,
> making a very thin - invisible micro scale layer on the element, but why
> that should be make the noise worse...? Something to do with the breakdown
> of the temporary hardness of the water during boiling perhaps.

With a scaled kettle, the element runs moderately above boiling - as the
scale insulates to a degree.
This means that if a steam bubble forms, and insulates more than the
water, then the scale patch locally heats up to the underlying element
temperature.

Then, when the bubble collapses, the water hits the patch of scale
that's now above boiling.
For a clean metal element, this doesn't happen, as the temperature is
closer to boiling.

My theory anyway.

meow...@care2.com

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Dec 9, 2006, 12:45:19 PM12/9/06
to
Andrew McKay wrote:
> Helen Deborah Vecht wrote:

> > I bought a reasonable Russell Hobbs from John Lewis 30 years ago; it's
> > still going strong...

> I remember buying one of those too, around that time. It was for our
> small office which didn't have a coffee machine (so the kettle got a
> fair amount of use). Worked flawlessly in all the years we were there.
>
> We now use cheapo electric kettles which we can buy in the local Tesco's
> for a fiver. They tend to fail fairly often (maybe once a year or so),
> but for that price who cares?
>
> Andrew

So youre paying £50 per decade instead of a fraction of that for
something decent. Plus the inconvenience of extra trips.


NT

Owain

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Dec 9, 2006, 3:14:57 PM12/9/06
to
meow...@care2.com wrote:

> Andrew McKay wrote:
>>We now use cheapo electric kettles which we can buy in the local Tesco's
>>for a fiver. They tend to fail fairly often (maybe once a year or so),
>>but for that price who cares?
> So youre paying £50 per decade instead of a fraction of that for
> something decent. Plus the inconvenience of extra trips.

Offset against the fact that new kettles every year won't need PAT-ing.

Owain


Andrew McKay

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Dec 9, 2006, 3:50:00 PM12/9/06
to
meow...@care2.com wrote:

> So youre paying £50 per decade instead of a fraction of that for
> something decent. Plus the inconvenience of extra trips.

I really don't understand the point you are trying to make. 30 years ago
when I bought that Russell Hobbs kettle there were no plasticky kettles
selling for a fiver. And from memory I recall the Russell Hobbs kettle
cost about £25. In today's money that might be £120 or more. It was
bought on company expense anyway so why should I care?

Are you trying to suggest that because I couldn't actually obtain a
kettle at a low price back then I have incurred expenditure which could
have been avoided? I really can't see how that could be.

I may misunderstand where you're coming from - perhaps you could explain.

Weatherlawyer

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Dec 9, 2006, 6:45:18 PM12/9/06
to

Ian Stirling wrote:
>
> I suspect it's that steel is more noisy, to some extent.
>
> And personally, I love the concealed element feature.
> I typically have around a cupfull of water in the kettle, which it boils
> really fast.
> It will happily boil half a cup.
>
> Not to mention the topic of the moment - energy saving.
>
> If you boil an extra cup of water 4 times a day, you spend 3 pounds a
> year extra, and spend an extra several hours a year waiting on the kettle.

First off if it is heating quickly it will be throwing off the
dissolved air in water quickly. Comparison with water that has boiled
then allowed to cool (thus removing a lot of the dissolved air) might
be illuminating.

And the fact it is a rapid heater is not a cause to believe it is a
rapid cooler. These things are made by slave labourers in Chinese
prisons or on a free market where the workers are paid something like
5 pence an hour and work 80 hour weeks.

They are not going to be highly motivated with those Victorian
conditions, are they?

30 years ago a kettle had chrome plate and was fitted with easily
repairable elements. Build quality was very very good. (For the era.)

When I fill my kettle I put one pint in it and pour one pint out (as I
drink tea or coffee in 1 pint mugs.) Immediately I empty the kettle, I
refill it as I don't like the idea of the thing overheating. As an
earlier poster stated, it is embedded and cannot cool like the old
fashioned type do.

I presume that is the answer to why they don't seem to last long,
though I may have just been unlucky initially. I cannot say.

My first experiences with the style was the poor longevity experienced
by other posters on this thread but with this immediacy about replacing
the water, there has been no problem.

Weatherlawyer

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Dec 9, 2006, 7:50:03 PM12/9/06
to

John Rumm wrote:
> Guy King wrote:
>
> > The message <457a0e99$0$8731$ed26...@ptn-nntp-reader02.plus.net>
> > from John Rumm <see.my.s...@nowhere.null> contains these words:

<The hot chocolate effect discussion neatly snipped (by other(s).)>

> >>Any other explanations you can think of?
>
> > Change of speed of sound in the fluid. That should affect the resonance
> > much as breathing helium affects the pitch of your voice.
>
> Yup - that could certainly be the case... you would probably expect to
> detect a pitch change with temperature as well then as the density of
> the liquid changes.
>
> > Rotation of the fluid in the container. Particularly if the fluid is
>

> The other problem with rotation based theories is that I tend to stir side


> to side rather than by inducing rotation. You still get the same effect.
>
> > What would really help would be having a name for the phenomenon to make
> > it easier to find other research.

I believe it is called the "hot chocolate effect":
http://www.sas.org/E-Bulletin/2004-04-02/feedback/index.html

I tried to engender a discussion on the subject once:
http://groups.google.com/group/sci.geo.earthquakes/browse_frm/thread/c7aa1cd44308c203/1a1cc2037b081d0e?lnk=gst&q=the+chocolate+effect&rnum=1#1a1cc2037b081d0e

But of course that was in a couple of scientific newsgroups so there
were no takers.

John Rumm

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Dec 9, 2006, 9:44:21 PM12/9/06
to
Andrew McKay wrote:

Hey Andy, welcome back...

not seen you in these parts for a while!

John Rumm

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Dec 9, 2006, 9:51:33 PM12/9/06
to
Weatherlawyer wrote:

> I believe it is called the "hot chocolate effect":
> http://www.sas.org/E-Bulletin/2004-04-02/feedback/index.html

Interesting... that would seem to support both my viscosity change /
damping effect and Guy's air bubble / velocity one.

d...@gglz.com

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Dec 10, 2006, 6:05:41 AM12/10/06
to

d...@gglz.com

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Dec 10, 2006, 6:08:55 AM12/10/06
to

Phil Addison

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Dec 10, 2006, 9:11:22 AM12/10/06
to
On Sat, 09 Dec 2006 16:02:02 +0000, in uk.d-i-y John Rumm
<see.my.s...@nowhere.null> wrote:

> Roger R wrote:
>
> > Now, using the bottled water it doesn't make any noise at all until just off
> > boiling, but even then its much less than before. I can hear the radio
> > again. So I think the noise is made much worse by hardness in the water,
> > making a very thin - invisible micro scale layer on the element, but why
> > that should be make the noise worse...? Something to do with the breakdown
> > of the temporary hardness of the water during boiling perhaps.
>
> It may be that the scale adds roughness to the surface which acts as a
> seed site making it eaiser for cavitation to occur....

Our kettle has been equally noisy from new, so I don't think lime scale
buildup is an issue, though the presence, or not, of dissolved lime may
well be. I'll give bottled water a try if I can bring myself to buy
some:(

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