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Just wondering - Heat Transfer

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.

Reply to
The Natural Philosopher
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down the connecting wires and from the connector to the air..

Reply to
The Natural Philosopher

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

Reply to
The Natural Philosopher

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.

Reply to
John Rumm

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

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Reply to
The Natural Philosopher

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

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

Reply to
The Natural Philosopher

Why bother?

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

Reply to
The Natural Philosopher

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

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

Reply to
T i m

well the OP was about efficiency.

Reply to
The Natural Philosopher

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.

Reply to
Martin Brown

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

Reply to
T i m

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?

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

Reply to
T i m

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

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

Cheers, T i m

Reply to
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.

Reply to
DerbyBorn

Where did the OP mention heat loss?

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

Cheers, T i m

Reply to
T i m

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

Sure but not under discussion. ;-)

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)?

I'm sure it is. ;-)

Cheers, T i m

Reply to
T i m

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.

Reply to
dennis

This was a conventional electric kettle but instead of the element just being a flat spiral of sorts, said element was bonded to a flat plate that formed a dummy inner 'bottom' to the (plastic) kettle.

Presumably the plate spread the heat over a larger area but looked as if there would be less heat transferred between the actual element itself (still visible under the plate) and the water.

Butanyroadup, the OP was wondering if a std immersion heater could be improved upon and I think it can (most things can, hence 'new and improved' versions that are 'better' that the originals). However, I'm not sure exactly how much quicker the cylinder would recover (for the same 'rating' of heater, all be it a cooler one may draw / deliver more energy because of a lower internal resistance), how much longer it would last (because it ran cooler) and how much better it might resist furring up (because it ran cooler).

On a similar vein, when Dad was on 'tankers' he said that when carrying pitch (or tar, I can't remember) they used steam from the boilers, passed though pipes running though the hold to keep the cargo 'liquid'.

If for any reason the cargo was allowed to cool to a point where it would harden, the heat from the steam pipes wasn't sufficient to get it all to melt again because of insufficient conduction through the cargo and hence no convection (and it would have to be dug out).

Now, *maybe* if the pipes were closer together or had some sort of 'finning' that would carry the heat further into the cargo, it could re-melt it all again?

Cheers, T i m

Reply to
T i m

It mostly doesn?t matter, because there isnt anywhere else for the heat to go.

Reply to
John

Sort of, that's why you can hear the kettling with the worst of them.

- and the element itself

Yes.

No. Basically there is nowhere else for the heat to go but into the water.

Reply to
John

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