I have an unvented electric immersion heater cylinder which heats the hot water for my household. The capacity is 200L and the temperature is set to 55°C.
The water heater is hard-wired to run overnight during cheaper off-peak hours only. This works reasonably well for most of the time, but occasionally during particularly heavy usage we find we run out of hot water by the evening so we're unable to take hot showers etc. at night.
If I increase the cylinder temperature to (e.g.) 65°C, will this effectively provide us with more "concentrated" hot water which will take longer to run out, assuming we continue to shower at the same comfortable temperature (~43°C)?
If yes, by how much longer might the hot water last?