JohnH wrote:

Thanks for the info there Stefek. After some consideration I think going
for one of these "electric combi boilers" is not really what I need. A
gas jobbie would be perfect, unfortunately no gas here.
So what someone else suggested on uk.rec.motorcycles was to use a mains
electric shower. They are cheap and should be simple enough to install
without the hassle and expense of ripping out the old tank etc..

They're certainly straightforward to install. (Don't, though, make the
allegedly common balls-up of trying to run them off an existing socket
circuit! They need their own, dedicated circuit, most often run in
10mmsq cable with a 40A breaker.) I find them fine for showering under,
but plenty of others prefer much more of a downpour for their shower.

An instantaneous heater just can't produce the hefty flow which some
people like (basic physics intervenes: water just takes a lot of energy
to heat up!). So, with a 9kW electric-instant, you're not going to get
more than a 'few' (can't be bothered doing the calculations yet again!)
litres/min; with a combi which goes up to say 24kW you'll get more -
about enough for most people's idea of a decent shower, but still
relatively slow to fill a bath and a PITA if other people are using hot
water at the same time. The effect is more pronounced in winter - to get
from incoming temp of say 5 degs up to comfortable showering temp of
about 40 is nearly twice the stretch than from a summer pipe-temp of
15-20 degrees. Hence the use of some sort of storage arrangement, so the
heating can happen over a longer time than the usage - whether that's a
conventional hw tank, heatbank, or the built-in small storage which some
combis have to give a higher initial flowrate...

Thanks for the tip about the handbrake on the car by the way, never
realised that could happen!

Nor did I, but I do now. Apparently it's common practice Oop Their Way
to leave the car in gear but handbrake off - though the island's not
quite pancake-flat, the bits with the roads all are...