Set Square wrote:
In an earlier contribution to this discussion,
wrote:
Hi


I need isolating valves for the CH so I can take rads off and still
run the rest. I've got 15mm or half inch copper, little room to
play
with, and 2-3m of pipe will be hanging off the valves in some
locations, so I'm thinking compression rather than pushfit.
Compression would also make reassembly easier, with egtting
everything lined up.

I ask cos Ive heard there are issues with full flow or not - which
of
the following screwfixes ok for CH? Whats the difference? I know
diddly about water valves.

13483 79p p290 (I see they have an arrow on, I dont know which way
the
water flows).

17447 =A31.20 p290

18796 2.29 p291

19933 2.29 p291

21860 3.19 p291

http://www.screwfix.com/


thanks,
NT

Only the very last of your examples is full bore. You can tell
because it
says so(!) and because it is very much fatter in the ball area -
allowing
space for a big enough ball to have a 13mm or so hole through it.

Whether or not it matters depends on the size of radiator. The others
are
likely to have a bore in the region of 6-8mm - which is ok for small
to
moderate rads, but too restrictive for large ones.

It's easy enough to determine flow direction. Water flows *into* the
radiator through the hotter pipe and *out* through the cooler pipe.
--
Cheers,
Set Square

FWIW there are 3' x 2' rads with the valves turned down a lot, plus a
bigger one set to full on. I gather there is agreement the 3' rads
should be fine on the cheaper valves, but not sure about the bigger
rad.

I could do with a clue on pipe freezing too, would be considerably
easier than drain the whole thing down. Presumably I'd need to freeze
both the rad pipes, and I'm guessing the quoted upto 35 minutes means
15-20 IRL.

That also leaves the q of the best way to cut the pipes: some of them
are up against the wall, making a hand held rotating wheel thingy
un-fittable-in-there. Angle grinder??


I can see it all going horribly wrong.... the ice plug prematurely
melted by the CH coming on when its not meant to, then the ice plug
shaken out by the angle grinder, the grinder showering live water
everywhere, the inaccessible stopcock being inaccessible, and the
entire system of black sludge being dumped over 2 floors of dwelling.
And the CH constantly filling with air once its all sorted. Heh, can
you tell I've not done this b4?


cheers, NT