John Rumm was thinking very hard :
I was not that keen on the idea that some times it would otherwise deliver 70
degree water to the taps.

Having a TMV on the cylinder output is a bit of a compromise, since it means
you don't have the benefit of running the very hot water through all the pipe
work like you would with multiple TMVs at every point of use.

I just have one TMV, on a toilet wash basin. I put that in so kids
could use the single tap I installed, to wash their hands
un-supervised, with no risk of too hot water.