design approach for new shower

[green grant]

I'm going to be installing a new shower. I have a combi. I won't be able to feed 2 showers from a single combi so I going to be adding a second combi just for this shower. I have reasonable pressure (6 bar) and flow rate of 16/l.min. In order to feed these combi's operating simultaneously, I need to ensure sufficient flow to each one.
Q. Do I have a single pressurised cold water tank that has 2 take-offs
Do I have 2 x pressurised tanks (for each combi)
Would an unpressurised tank suffice or will it absolutely need to be pressurised?
Is there another way?

 

[ShaunCorbs]

No to the combis

change your system type either

gravity cylinder with a 80 gallon cold tank with a shower pump on the outlet to the cylinder

mains unvented cylinder depending on your mcw

 

[gmartine]

No to the combis

change your system type either

gravity cylinder with a 80 gallon cold tank with a shower pump on the outlet to the cylinder

mains unvented cylinder depending on your mcw

Shaun you know this guy, he knows more than all of us put together and opted that brilliant Japanese boiler.

 

[green grant]

Shaun you know this guy, he knows more than all of us put together and opted that brilliant Japanese boiler.

I added a 75l header tank which has a 22mm mains water feed and a 22mm outlet to the boiler intake. The result is that there is no drop in operational pressure and flow rate when other cold taps are turned on so the boiler does not reduce flow rates (it has set points for hot water which cannot be exceeded hence the sensitivity)