Alternative to venturi

[calorific]

This thing about venturi shower mixers got me thinking. The way I understand it is that the higher pressure (and subsequent flow rate) of cold water mains is used to draw hot water.

Now, surely someone must have thought about and designed a twin pump which has one side driven by cold water mains and which therefore would pump hot water through at a similar rate. This would mean that any shower mixer could be used and not a limited range currently using venturi technology. It would also not require any electricity to operate it, and no negative/positive head would apply.

So has anyone designed these and are they in manufacture?

 

[Charnwood]

Varying the temperature in your hypothetical set-up would upset the equilibrium. H and C would have to be mixed based on flow rate, not temperature. Probably.