"TheScullster" wrote in message
...


Looking at the pipe runs and radiator sizes involved upstairs, are 15mm
mains simply not up to the job?

Do the pipes branch off from a 22mm feed or do they run in 15mm from the
ground floor?


Thanks to anyone who has even managed to read this far!

Have you tried bleeding the system?
Have you tried opening (just a bit) the lock shield valves on 6&7?