How can I fix my heating system?

Its airlocked....try bleeding the radiator again - it could help if you turned some of the other rads off to increase the pressure. Failing that, turn off the rad valves, disconnect from rad - which will drain down- and open them again, one at a time, into a shallow tray. Reconnect them, open both slowly at the same time, rad bleed valve open.

John
October 2009