TW, you did say 'iso valve'? Then yes, preferably a lever type so that at the start of the frosty season anyone can turn it off, nip outside to open up and so give some room for expansion if any lingering water does freeze.
FIFTY QUID!!!!Why not fit two and have hot water supply as well.
TWENTYFIVE QUID!!!!
Presumably, the mechanism stretches up the inlet pipe to isolate it from the extremes of winter:
View media item 45706
Not convinced it would be worth the ridiculously high price. And you've still got to fit a DCV somewhere.
You should use one of these: http://www.screwfix.com/p/hose-union-back-plate/56415I don't use a backplate, but a 15mm x 1/2" connector.
standard outside tap is going to set you back £7,
i'm not sure it would, as a trade price.
Has anyone an answer to the OP's ACTUAL question ? I am sure it is mandatory for internal taps, and would assume it is for OT's.
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