Converting gravity shower to mains cold/pumped hot

[dmccormick]

Can you supply mains cold and pumped hot to a thermostatic mixer shower. If so, do you need a non return valve on the mains to the valve; do you also need one on the hot and if so, which side of the pump should it go ?

 

[Bahco]

Supplies need to be balanced so you will need to feed cold from the cistern

 

[dmccormick]

But if the hot is pumped and the cold not then it won't be balanced.
Was hoping mains cold and pumped hot would be good enough match.

I know ideally you pump both or pump the blended output from the valve, but both of those will require breaking into the tiles and messing about with floor boards.