On Sun, 25 Dec 2016 09:31:05 +1100, "John" wrote:

snip

So, are you saying that a 'kettling' element *will* be transferring
it's energy to the water as effectively as one with say twice the
surface area that wasn't kettling?

Yes, because there is nowhere else for the heat to go.

(straight question).

Just as well, I don't like bent questions.

;-)

So we aren't talking directly about a loss of energy here, but
a loss of efficiency (because of kettling and other variables).

That isnt loss of efficiency, all the heat still ends up in the water.

Ok, but only the energy that is available?

So, no kettling, good thermal conductivity with the water, plenty of
time for the water to convect and take the heated water round the
cylinder. Heater element stays reasonably cool and therefore low
resistance therefore runs at full marked power.

Overdriven element (for the surface area), kettling, decreased contact
with the water (steam insulating the element from the water),
increased element temperature, higher resistance, reduced energy
consumption from rated, lower actual output?

Now, it may not make much of a difference ITRW but we were just
'wondering' about such things here. ;-)

Cheers, T i m