On 14/11/2017 22:55, The Other John wrote:
On Tue, 14 Nov 2017 11:59:28 -0800, tabbypurr wrote:

On Tuesday, 14 November 2017 15:44:07 UTC, Martin Moores wrote:
replying to Stuart, Martin Moores wrote:
I have a load of 9mm microbore in my house. It's old stuff I have heard
and impossible to get fittings for. I need to replace a few joints now
and have had to replace loads with 10mm.
If anyone knows of a supplier for 9 mm microbore please let me know.

If I were in that position I might mandrel & hammer it out to 10mm.


NT

I presume the OP means pre-metric 3/8 inch microbore which is what I've
got. When I had to have a couple of TRVs and lockshield valves replaced
my heating chap used 10mm fittings with extra solder and we haven't had
any leaks (touch wood).

Assuming it is copper.

My parents had a system that lasted from 1972 to about 2008 and was
plumbed in 12mm, 10mm, 8mm and 6mm plastic. The only copper was the 22mm
connecting boiler and pump to both floors.

Gradually more and more was replaced with copper from the mid-'90s as
the plastic had become brittle and was very easily cracked if disturbed.

That meant extra work, as the original system had no lockshield valves
and all but two radiators were fed and returned from a single corner
(the valves had both flow and return connections and used an extension
pipe within the radiator to get the feed to the far end. As copper was
put in, the self-balancing of the carefully sized piepwork was disturbed
and feed and return had to be separated to opposite ends of the
radiators to allow lockshields to be fitted.

SteveW