Thanks for ur detail explanation.
I know a clearer picture now.
As for me, i only spend 10 to 15mins time in shower. But for my wife she spend 30 to 45mins showering. So likewise, if using instant heater it will be consuming 3kw of power over the entire 45mins = high electrical consumption.
I have checked Ariston site, they offer quite a number of models, some with 1.5kw, 2.5kw and 3kW. 1.5kw models are they multi point?
i only require to supply to 2 bathrooms. so which model is recommended for my usage.