On Mon, 16 Apr 2007 16:40:43 +0000, nospam wrote:

Hello,

I bought some full bore 15mm isolation valves for my shower, as I
thought the "standard" valves with their narrow centres might impede
the flow. Was I right to be worried?

Anyhow, I realise the full bore ones need some space for their
mechanism and would not be 15mm wide but all the same, they don't seem
to have an internal diameter that much bigger, so what's the point?

Were they from Toolstation? Or maybe not, but TS do some 'full-bore'
valves which are nothing like full bo just a bit wider bore than
standard 'ballofix'-type isolation valves. Cue Trading Standards ...

But in answer to your first point I would use genuine full-bore valves
on the gravity inlet to a shower but could use a less-than-full-bore
valve on the higher-pressure outlets, or on a mains-pressure-fed system
(e.g. electric shower, combi, unvented or heat bank).