On 06/02/2015 22:44, Andrew Gabriel wrote:
In article ,
Roger Mills writes:
They *do* cause a flow restriction, so it's better not to use them on
big radiators. They're ok for small ones though. The larger full-bore
lever isolation valves are far better when you don't want any
restriction - but you don't too many of those on show in your living room!

The other problem is that there isn't a valve which will operate
reliably after many years of not being operated. You need to make
sure your annual test/check of the system includes opening and
closing all these valves, or after a few years, you will find you
can't do it anymore. There are 4 x 22mm full bore valves in my
system for isolating some sections in case of any leaks which I
ignored for 10 years, and then found they will no longer turn.

I must remember to move mine! They have only been in a couple of years.