Hi I have a quick question regarding the type of valve that I should
use in the following project:
We are re-fitting our bathroom and have decided to go for a thermo
mixer valve that will supply either the bath or the over bath shower
via two stop cocks. To make the shower worth using I've decided on a
Stuart Turner pump in the airing cupboard and having read other posts
on here am planning on running 22mm pipe wherever possible.

Question is: The current value I have chosen (Bristan) is not a 3/4"
model, but has just 15mm connections, will this make the use of a high
qaulity pump like the monsoon not worth the expense and where should I
drop 22-15, at the valve itself?

Also the output from the valve will be split, one feed to the bath and
one to the shower head, should these be back in 22m as well. The idea
of filling a bath with a single blended 15mm feed does not fill me with
joy, or am I missing something?

Any tips greatly received.