Storage combi - how do they actually work?

[Gasguru]

For that price just shove in a 120 litre unvented and have the luxury of an immersion heater backup when the boiler dies.

 

[lubemonkey]

Thanks for the replies all. Am erring away from storage combis now I know how they work.
Undecide on way forward as yet, but thought I'd do some pressure and flow tests to check if that's going to restrict my options:

Gauge on outside tap, static pressure 5.3 bar.
Kitchen tap full on 3.3 bar.
Kitchen tap on a happy maximum 4.8 bar.
Downstairs toilet flushed 4.3 bar
Upstairs toilet flushed 4.8 bar
Upstairs electric shower on 5.0 bar

Open flow at outside tap is 26 l/min.

I realise there are no dynamic flow figures there. I am expecting to fit flow restrictors to all outlets and a thermostatic shower mixer in the main bathroom (sticking with the electric shower in small bathroom).
At a high level does this sound like my options are still open on the boiler front?
Thanks in advance.

 

[Gasguru]

So it appears you could have 2 or 3 outlets open and you'll still have a bar of pressure...you should be fine whatever the solution.