8 people, 5 bathrooms. What indirect cylinder size and what coil kW rating?

[harrypotter]

Looking at getting a new cylinder installed as the current 250l unvented one doesn't recover quickly enough. Sometimes HW demand is low with only a few people, other times it's high with up to 10 people. I think a fast recovery cylinder of similar size would be better than adding another cylinder. I'd be looking to switch from Y-plan to DHWP too. Should I be looking at a high kW for the coil? I assume the higher it is, the more heat it can transfer, so faster recovery. Since my boiler is 32kW, is something at least 32kW what I should be looking for? With all that hopefully I can get away with only a 250 or 300 litre cylinder?

 

[muggles]

Yeah a Joule High Gain 300 would do you nicely on DHWP

 

[harrypotter]

Yeah a Joule High Gain 300 would do you nicely on DHWP

Do you think a one big tank would be the most efficient way of doing it rather than two smaller tanks? I'm just trying to think what the best solution would be as it's roughly 40% of the time 2 people, 40% of the time 4-6 people and 20% 8-10 people. Given the thermostat for the cylinder is near the bottom it'll want to heat the whole 300L, which seems like a waste if it's only two people. I suppose however these modern cylinders really don't lose much heat over 12 hours...