Gordon Henderson coughed up some electrons that declared:

Another daft question, (thanks for all the screwfix shop replies - works
a treat!), but the incoming mains to our house is a black semi-flexible
pipe of about an inch in external diameter. This has what looks like an
odd coupling that looks like some sort of compression joint to 15mm pipe
where I fitted a stop cock some years back... (works fine).

Not daft - been there done that.

Mine was 1/2" black alkathene (phone call to water board who took a stab at
identifying by description). As other's have said, yours is almost
certainly the same.


Our water pressure is high (8 bar), but flow rate low (under 10 litres
a minute) I think due to some external restriction in the pipe work -
which I'm not prepared to dig up at this point in time.

I would say you have a restriction. I have 12-13m of that pipe at 7 bar and
I can get 50+l/min out of it.

I'd like to remove the join to the 15mm pipe, fit a coupler to 22mm pipe,
a quarter turn full-bore "stop cock" to make it fool-proof for wifey,
then fit a pressure reducer to 3.5 bar, and then run 22mm pipe from
there - hoping to get a better flow rate at a pressure that'll reduce
the possibility of burst pipes (not a plesant sight round here when it
happens - as it did to our neighbours recently)

http://photos.dionic.net/v/public/bu..._0019.jpg.html

http://photos.dionic.net/v/public/bu..._0016.jpg.html

I went via blue MDPE - not sure if that's your intention. Or do you want to
go direct from 1/2" to copper 22mm?


If the former, I used

http://www.bes.co.uk/products/168.asp (part 11330) to go from 25mm MDPE to
copper (don;t forget the pipe insert).

and 13544 on the same page to go from 1/2" to 25mm MDPE.

If going from 1/2" to copper I suspect you could just use the latter as it's
rated for 22mm copper.

1/2" alkathene can be made off with a compression joint similar to 11330
above, but I'm not sure where you'd get one with the correct olive and
insert.


Peglar 1/4 turn full bore valves are good - and for the pressure reducer I
recommend

http://www.hav.co.uk/products/shw-de...13086&cid=1051

It doesn't mess with the flow at all. I still get 50+ l/min through it at
any pressure setting.

You'll need some gas PTFE (or a *lot* of water PTFE or some other potable
threadlok type stuff) to seal the pressure dial on. For some sick reason
they used parallel BSP threads and there's no seat to seal against - and if
there were, you'd not get the dial in the right place.

Cheers

Tim