"John Orrett" wrote in message
k...

At present we need both the immersion
and the boiler to give us a decent
bathful of hot water.

Is the cylinder small? Does it take an age to heat up the cylinder with the
boiler.

My wife wants one of these 'shower baths', the ones with a bulge at one
end.
I don't know capacities or volumes of our standard bath compared to a
shower
bath, but it looks to me like it would need a lot more hot water or end up
with half a bath!

You will require serious surgery here. You will need a larger cylinder and
power shower pump at least Providing your cold mains are good enough
consider:

1. A Heat Bank (does away with the tank in the loft)
2. High Flowrate combi (does way with cylinders and tanks)
3. use two combi's to give a very high flow of instant water (does way with
cylinders and tanks).

As your boiler is an old model and you need high flows, consider No. 3.
seriously. See my current post on this.