Hi Owain and TCC, thanks for your replies.
Unfortunately there isn't any room for a second immersion tank.
Before I resign myself to an electric shower - I wondered about this device: http://www.energybulbs.co.uk/redring+12kw+powerstream+instant+water+heater+(rp12)/2821466957
As a...
My flat does not have gas, only electric. The water heater is an immersion system, which takes a while to heat up. It also empties quite quickly, so while the first person to shower in a morning has lovely hot water, the third person showers in cold water.
It'll be a holiday let from...