Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

100% efficient. There is nowhere else for the heat to go but into the water.

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?

dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

DerbyBorn wrote:
dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.


One way might be to surround the element with something fluid that could
redistribute the heat by convection. Don't suppose it'll ever catch on
though...

Tim

--
Please don't feed the trolls

On 12/24/2016 10:07 AM, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


pedant
If you put fins on the cladding the heat transfer would improve, and the
resistive element would run a bit cooler. That might improve its life?
Also, a cooler element would have lower resistance, hence slightly
higher current and output.
/pedant

In article ,
DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

Since the only thing generated by the electricity they use is heat, where
can it go other than into the water?

(It might also produce 'light' like UV or infra red - but in such a tiny
amount as can be disregarded.)

--
*If love is blind, why is lingerie so popular?

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 24 Dec 2016 10:55:59 +0000, Bob Minchin
wrote:

DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

100% efficient. There is nowhere else for the heat to go but into the water.

Great. No need for that bulky insulation round the cylinder then ;-)


--

Graham.

%Profound_observation%

On Saturday, 24 December 2016 11:08:19 UTC, DerbyBorn wrote:
I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

Might that help reduce scaling on elements in hard water areas?

Owain

One way might be to surround the element with something fluid that
could redistribute the heat by convection. Don't suppose it'll ever
catch on though...

Tim

Nice one!

On Sat, 24 Dec 2016 11:08:17 GMT, DerbyBorn
wrote:

dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.


I think the typical installation orientation of nearly vertical would
not help with any 'finning' that would in turn help the conduction and
the convection that supports it.

If the (typically orientated) element had some longitudinal 'finning',
maybe in the form of a cross, that may increase the surface area
sufficiently and not interfere with the convection too much?

Interesting thought though. ;-)

Cheers, T i m

On Sat, 24 Dec 2016 11:23:23 +0000, Graham. wrote:

Great. No need for that bulky insulation round the cylinder then ;-)

Who has those these days?

I was thinking that if it was twice the area the surface temp could be
proportionally lower - but getting the heat from the resistance wire to the
surgace could become and issue.

On 24/12/2016 11:21, Dave Plowman (News) wrote:
In article ,
DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

Since the only thing generated by the electricity they use is heat, where
can it go other than into the water?

(It might also produce 'light' like UV or infra red - but in such a tiny
amount as can be disregarded.)


And a little bit of noise on some of them.

--
Adam

DerbyBorn wrote:

dennis@home wrote:

DerbyBorn wrote:

Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

They convert 100% of the electricity to heat.
What efficiency would you like to improve?

I sort of knew all that - but could the dissapation be improved

You could put fins on the element, it would speed the recovery time.

On 24/12/2016 11:08, DerbyBorn wrote:
dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

If you live in hard water area, the element might be furred up, but that
would only slow down the rate of heat transfer.

A decent amount of insulation around the tank is more important if
electric is the main heating source.

On Sat, 24 Dec 2016 13:06:46 +0000, Chris Hogg wrote:

On Sat, 24 Dec 2016 11:08:17 GMT, DerbyBorn
wrote:

dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

The core of the element will heat up until the heat (energy) taken
away into the water by conduction and convection balances the
electrical energy dissipated in the core of the element. At that
point, equilibrium is established. The water itself won't get much
hotter that 100C (there's sometimes a slight head depending on where
the hot tank is relative to the header tank). When the power is
switched off, any residual heat in the element will be rapidly taken
up by the water. The elements consist of a nichrome heating wire
surrounded by magnesium oxide powder insulation; they are designed to
get quite hot, just like the elements on an electric cooker or in an
electric kettle. They've been around for a very long time and usually
last a very long time IME. I don't see how you could improve on them
significantly.

I think the OP was considering the transfer of energy between the
element and the water more than the efficiency of the element itself.

Ignoring any losses from the cylinder and surrounding pipework, isn't
the transfer of energy between the element and water a function of the
temperature / power of the element and the ability of the water to
absorb said energy?

So, if the element was just a single 30cm 10mm diameter 'loop' and was
rated at say 10kW, wouldn't the water around the element boil (and I'm
not sure how that would affect the energy transfer / efficiency)?

The same element rated at only 1kW would just take longer to heat the
water.

So, if you took the 10kW element and increased it's surface area,
wouldn't the element be able to transfer the heat energy to the water
more efficiently (no 'kettling')?

After all, it's just the same process as a heatsink but in reverse,
the only question is the science of the temperature differential
between the element and the water and how that effects heat transfer
efficiency?

Cheers, T i m

On 24/12/2016 11:08, DerbyBorn wrote:
dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

It does not really make any difference. If you stick 3kW in, then that
is what must come out. The harder you make it to get out, the hotter the
element will run, but eventually equilibrium will be reached.

Convection in the cylinder will take care of mixing the heated water.


--
Cheers,

John.

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

On 24/12/16 12:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

they are 100% efficient more or less. Certainly in the high 90s.

Heat loss is seldom through the element, so its more about heatloss from
the tank itself.

On 24/12/16 12:55, Bob Minchin wrote:
DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

100% efficient. There is nowhere else for the heat to go but into the
water.

down the connecting wires and from the connector to the air..

On 24/12/16 13:08, DerbyBorn wrote:
dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

No.

Only improvement would be to thermally isolate element from incoming
mains wires by eg. using RF or magnetic coupling through some insulation.

On 24/12/2016 12:14, Andy Burns wrote:
DerbyBorn wrote:

dennis@home wrote:

DerbyBorn wrote:

Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

They convert 100% of the electricity to heat.
What efficiency would you like to improve?

I sort of knew all that - but could the dissapation be improved

You could put fins on the element, it would speed the recovery time.

Unless the rate of conduction away from the element is so poor that its
cycling on its stat before the cylinder reaches set point, then the only
determining factor in the recovery time is the rate of heat input - the
amount of energy required is determined by the amount of water and its
start temperature.


--
Cheers,

John.

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

On 24/12/16 13:13, newshound wrote:
On 12/24/2016 10:07 AM, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


pedant
If you put fins on the cladding the heat transfer would improve, and the
resistive element would run a bit cooler. That might improve its life?
Also, a cooler element would have lower resistance, hence slightly
higher current and output.

So run it at a higher voltage to get back to where you started
/pedant

On 24/12/16 13:23, Graham. wrote:
On Sat, 24 Dec 2016 10:55:59 +0000, Bob Minchin
wrote:

DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

100% efficient. There is nowhere else for the heat to go but into the water.

Great. No need for that bulky insulation round the cylinder then ;-)


He wasn't talking about how efficient the water was at retaining heat.

That's nowt to do with t'element laddy.

On 24/12/16 13:59, T i m wrote:
On Sat, 24 Dec 2016 11:08:17 GMT, DerbyBorn
wrote:

dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.


I think the typical installation orientation of nearly vertical would
not help with any 'finning' that would in turn help the conduction and
the convection that supports it.

If the (typically orientated) element had some longitudinal 'finning',
maybe in the form of a cross, that may increase the surface area
sufficiently and not interfere with the convection too much?


Why bother?

Its all expense to make something 100% efficient...100% efficient!


Interesting thought though. ;-)

Cheers, T i m

On 24/12/16 14:04, DerbyBorn wrote:
I was thinking that if it was twice the area the surface temp could be
proportionally lower

So ****ing what?


- but getting the heat from the resistance wire to the
surgace could become and issue.


No it wouldnt.

On 24/12/16 15:35, T i m wrote:
So, if the element was just a single 30cm 10mm diameter 'loop' and was
rated at say 10kW, wouldn't the water around the element boil (and I'm
not sure how that would affect the energy transfer / efficiency)?

It would make it 100% efficient like it already was.

Christ almighty, the lefty****s here are displaying an amazing total
lack of understanding of the basic physics of heating, just like they do
in the real world...no wonder we have wind turbines with these ****s
voting for people like themselves in government.

Do you really care whether your tank reaches thermal equilibrium in 3
minutes or 4 minutes?

On Sat, 24 Dec 2016 15:42:08 +0200, The Natural Philosopher
wrote:

snip

I think the typical installation orientation of nearly vertical would
not help with any 'finning' that would in turn help the conduction and
the convection that supports it.

If the (typically orientated) element had some longitudinal 'finning',
maybe in the form of a cross, that may increase the surface area
sufficiently and not interfere with the convection too much?


Why bother?

It was a hypothetical question. You may not have understood such? ;-(

Its all expense to make something 100% efficient...100% efficient!

I bet you don't know why people climb to the top of mountains when
there is a perfectly good cable car either.

See, it's not all about efficiency directly but questioning *if* there
were any *other* improvements that could be made that *could* have
other benefits ... like faster recovery-time or reduced scaling.

Cheers, T i m

On 24/12/16 16:00, T i m wrote:
On Sat, 24 Dec 2016 15:42:08 +0200, The Natural Philosopher
wrote:

snip

I think the typical installation orientation of nearly vertical would
not help with any 'finning' that would in turn help the conduction and
the convection that supports it.

If the (typically orientated) element had some longitudinal 'finning',
maybe in the form of a cross, that may increase the surface area
sufficiently and not interfere with the convection too much?


Why bother?

It was a hypothetical question. You may not have understood such? ;-(

Its all expense to make something 100% efficient...100% efficient!

I bet you don't know why people climb to the top of mountains when
there is a perfectly good cable car either.

See, it's not all about efficiency directly but questioning *if* there
were any *other* improvements that could be made that *could* have
other benefits ... like faster recovery-time or reduced scaling.

Cheers, T i m

well the OP was about efficiency.

On 24/12/2016 11:08, DerbyBorn wrote:
dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

They convert 100% of the electricity to heat.
What efficiency would you like to improve?

I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

No. The only way you can improve on an immersion heater is by decreasing
the amount of water that is heated to exactly match demand with a flash
boiler. Once you have to store hot water losses mount up.

It is easy to turn electricity into heat with close to 100% efficiency -
it is going the other way that is difficult.

--
Regards,
Martin Brown

On Sat, 24 Dec 2016 15:47:04 +0200, The Natural Philosopher
wrote:

snip arrogant TNP left-brain thinking

Do you really care whether your tank reaches thermal equilibrium in 3
minutes or 4 minutes?

1) I didn't post the question.

2) I don't have a hot water cylinder

3) I understand that people (other than you) can have such 'right
brained' discussions.

4) You aren't obliged to join in.

Cheers, T i m

On Sat, 24 Dec 2016 13:36:00 +0000, John Rumm
wrote:

On 24/12/2016 11:08, DerbyBorn wrote:
dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

It does not really make any difference. If you stick 3kW in, then that
is what must come out. The harder you make it to get out, the hotter the
element will run, but eventually equilibrium will be reached.

Yup, *eventually* ... but what if there was some value (like recovery
time or minimising element scaling or failure due to overheating) that
could be gained by some minor design change?

Convection in the cylinder will take care of mixing the heated water.

Yes, in general it will (and does of course), but what if there were
still some improvements to be made, especially if they are cheap,
simple to implement and backwards compatible?

Like, many of our electric kettles have had just the element coil in
the bottom but at least one other had the element fused to a plate
covering the entire bottom of the kettle. Why would anyone bother to
do that if there was only one good design?

Cheers, T i m

On Sat, 24 Dec 2016 15:38:59 +0200, The Natural Philosopher
wrote:

On 24/12/16 13:08, DerbyBorn wrote:
dennis@home wrote in news:585e54ca$0$1285$b1db1813
:

On 24/12/2016 10:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?


They convert 100% of the electricity to heat.
What efficiency would you like to improve?



I sort of knew all that - but could the dissapation be improved - I imagine
there is incredibly hot water next to the element - and the element itself
will be very hot. Spreading the 3kW over a larger area - could this result
in the element running cooler and the heat distributing better.

No.

But you don't explain 'why not' (for some reason), however
insignificant any gains may be seen ITRW.

Only improvement would be to thermally isolate element from incoming
mains wires by eg. using RF or magnetic coupling through some insulation.

We were ignoring any such losses (by 'we' I mean the OP and any other
right brainers). ;-)

Cheers, T i m

Wow ! Some folks get wound up.

I don't have a cylinder either! If the element was as small as possible -
how would it compare with a much larger one of the same power input? The
water needs to convect and conduct to get the heat away from the element.
Seems comparable to having a kettle with a large base on a big hotplate
compared with a smaller base on a smaller hotplate - same wattage. One
would be noisier I think.

On Sat, 24 Dec 2016 15:37:02 +0200, The Natural Philosopher
wrote:

On 24/12/16 12:07, DerbyBorn wrote:
Are immersion heaters as efficient as they could be? Could the tubular
element be improved upon - or doesn't it matter?

they are 100% efficient more or less. Certainly in the high 90s.

Heat loss is seldom through the element, so its more about heatloss from
the tank itself.

Where did the OP mention heat loss?

You really don't get the whole concept of 'Just wondering' do you? ;-(

Cheers, T i m

On Sat, 24 Dec 2016 14:02:42 +0000, Martin Brown
wrote:

snip

No. The only way you can improve on an immersion heater is by decreasing
the amount of water that is heated to exactly match demand with a flash
boiler.

Ok, so is that to do with the rate at which heat can be transferred to
the water?

Once you have to store hot water losses mount up.

Sure but not under discussion. ;-)


It is easy to turn electricity into heat with close to 100% efficiency -

Understood, but how about the design efficiency of transferring the
heat from a submerged heating element to the liquid that surrounds it?

Are (those who don't get this 'Just wondering' thing/) we saying that
there is *no way* that the deign of a conventional emersion heater
couldn't be changed / improved to make the process say quicker or less
prone to scaling (especially in direct HW installations)?

it is going the other way that is difficult.

I'm sure it is. ;-)

Cheers, T i m

mechanic Wrote in message:
On Sat, 24 Dec 2016 11:23:23 +0000, Graham. wrote:

Great. No need for that bulky insulation round the cylinder then ;-)

Who has those these days?

Anyone who wants an alternative way of heating the water if the
boiler fails, or prefers to have an airing cupboard, or needs a
store of hot water to cope with parallel demands (e.g. from
several showers in use simultaneously).
--
Biggles


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On 24/12/2016 13:47, The Natural Philosopher wrote:
On 24/12/16 15:35, T i m wrote:
So, if the element was just a single 30cm 10mm diameter 'loop' and was
rated at say 10kW, wouldn't the water around the element boil (and I'm
not sure how that would affect the energy transfer / efficiency)?

It would make it 100% efficient like it already was.

Christ almighty, the lefty****s here are displaying an amazing total
lack of understanding of the basic physics of heating, just like they do
in the real world...no wonder we have wind turbines with these ****s
voting for people like themselves in government.

Do you really care whether your tank reaches thermal equilibrium in 3
minutes or 4 minutes?



While some here may like to discuss physics there are others that are
****s. You can work out for yourself which you are.

On Sat, 24 Dec 2016 15:27:44 +0000, dennis@home
wrote:

On 24/12/2016 13:47, The Natural Philosopher wrote:
On 24/12/16 15:35, T i m wrote:
So, if the element was just a single 30cm 10mm diameter 'loop' and was
rated at say 10kW, wouldn't the water around the element boil (and I'm
not sure how that would affect the energy transfer / efficiency)?

It would make it 100% efficient like it already was.

Christ almighty, the lefty****s here are displaying an amazing total
lack of understanding of the basic physics of heating, just like they do
in the real world...no wonder we have wind turbines with these ****s
voting for people like themselves in government.

Do you really care whether your tank reaches thermal equilibrium in 3
minutes or 4 minutes?



While some here may like to discuss physics there are others that are

snip

I don't think they (those left brainers) can help it, it's just how
they are wired (so how they react is sort of to be expected).

And the irony is that they can't see what they are, only the right
brainers can. ;-)

You can easily tell said 'cold and prickly's apart from the 'warm and
fuzzy's' apart just from their replies in this thread.

But hey, the world needs pure analytical machines or we wouldn't get
sites like Gridwatch. ;-)

Cheers, T i m

On 24/12/2016 14:11, T i m wrote:

Like, many of our electric kettles have had just the element coil in
the bottom but at least one other had the element fused to a plate
covering the entire bottom of the kettle. Why would anyone bother to
do that if there was only one good design?

The flat plate ones are so you can boil less water and hence may save
energy.
However unless they are insulated underneath or the plate is thick they
will lose a bit more energy out of the base than a kettle with an
immersed element.