Hi,

I have a plumber who's fitting a Stuart Turner Showermate Shower Pump
& Hudson Reed 3/4" thermostatic valve (from Bathstore) for me (you
might argue this wasn't DIY, but I have fixed the electrics myself!).
Question is this (and I think it is on topic for the ng): he's using
15mm flexi-piping: about .5 m from the hot tank to the pump, and about
3m from there to the valve (all but the last 50cms which are 22mm
copper pipe). The instructions both for the pump & the valve say "use
22mm piping if possible", but he (and the wife) reckon that as the
pump entry & exit tubes are 15mm, it's not going to make too much
difference.

So, if any of you have experience of this sort of set-up, please tell
me: is this going to turn our rainstorm into a piddle? Or not really.

Ah yes: gravity system; hot tank, pump & bath on first floor, cold
tank on second floor.

And a PS. The obvious cold feed to use for the pump might be straight
from the mains, I haven't checked. Would that be a bad idea?

Thanks.

James