"Colin M" wrote in message
...
Roger

Thanks for that. I have thermostatic valves in most of the house but a
couple of rads without. They are set with an 11 degree drop (per balancing
technique in FAQ) and are therefore providing a path for pumped water at
all
times.

Funny thing was the gate valve was almost fully open (and the radiators
not
balanced) so I wonder how much pride house builder plumbers really take in
their work.

Colin M



If you shut the by-pass, you may get slightly more water going through the
rads - resulting in a lower drop - but that shouldn't matter. It shouldn't
affect the balance - but it may be as well to re-check it.

Roger