On 06/12/17 19:03, James Wilkinson Sword wrote:

I have a boiler with a 25mm pipe output.

You mean 22mm.

This branches into 15mm pipes
for different areas (house, garage, hot water).* Then that branches into
8mm pipes for each radiator.* All radiator valves are opened fully.* All
radiators get piping hot.* You only need to balance if your supply pipe
isn't big enough to give water to everything downstream of it.


That's fine if you like microbore. I was strongly advised against it.