Static pressure 3.0 bar.

Flow from cold outside tap ~17l/min.

Accepted that there will have to be flow restriction on the cold taps in
the house to prevent loss of hot water pressure.

Just looking at mixer valves.

http://www.screwfix.com/p/triton-tes...ower-flexible-
exposed-chrome/36111

"Water minimum flow rate
For best performance within the specified running pressure range a minimum
flow of 8 litres per minute should be available to both inlets."

Now does this mean that you need a total flow of 16 litres per minute
evenly distributed between the hot and cold?

In which case it is just in spec. with a 17litres per minute total flow.

Or does it mean 8 litres per minute shared between the two outlets which
is well within spec.

I think it is total flow of 16 litres per minute, but just double checking.

Cheers

Dave R