Thanks very much for your detailed answer, TicklyT. Today I learnt about 'stratification' :)
Your post told me everything I wanted to know.
The only small point I'd like to make is that there is no cold water storage cistern; there simply are no other water tanks in the house/attic/etc.. I...
Thanks for your reply, calorific. The hot water pressure is actually much lower than the cold water pressure, so maybe the water isn't topped up instantly. Perhaps it is 'gravity fed', as you said.
This is the closest I can find online:
http://www.partsarena.co.uk/baxi/System/DATA/Dx/DS1/installation/3999/I51-3999/I51-3999-F006.gif
If it helps, there's one expansion tank (it has a pressure gauge on it and it is connected to the main tank, so I'm relatively sure it's an expansion tank)...
Basically, when I use the shower, is cold water fed into the hot water tank, to top it up immediately, or does no new water enter the tank until I turn the central heating system on?
I hope that makes more sense :)
I have an electric, Amptec central heating system:
There are heating tubes, in the airing cupboard, though which water is pumped. As the water cycles through these tubes, and back to the hot water tank (in the attic) it gradually heats up.
What I'm left with, after the central heating has...