Further to my enquiry about shower pumps, to maximise my "new shower"
experience i am also considerring changing the mixer taps to a
thermostatic bath/shower mixer tap. this would also have the benefit
of replacing the shower hose with one that can tolerate the higher
pressures and also provide more variations in spray type from the
shower head.

However, i have only either seen one from Aqualisa that is around
£200, or else one from an ebay shop for around £80 [less well known
brand but 3 year manuf warranty quoted in details of product].

This latter product has prssure ranges from 0.5-5Bar so within the
1.4bar pump pressure. However, if i use the shower head/bath filler
with the pump switched off [ie gravity pressure only] and it were to
be at a pressure below the quoted pressure of this mixer tap, what
happens? no water comes, rumbling in pipes, air blocks or some other
such catastrophy?

advise about the above, as well as comments/pointers to other
inexpensive [relative to the aqualisa] thermostatix bath/shower mixer
taps is greatly appreciated

Riz