"Andy Hall" wrote in message
...

1) Use the bathroom radiator as a bypass for the boiler. If you look
at your system, you may find a pipe between the flow and return
from/to the boiler before the motorised valve(s) with something like a
radiator lockshield valve on it. The purpose of this is so that if
the CH and HW thermostats are satisfied and the boiler is in full
burn, there is a path so that the pump can continue to run and
dissipate the heat.

This is how my towel rail is configured and I wish it wasn't! When it pumps
through the towel when all other rads are off it makes quite a noise and
stops me from sleeping at night.