At the moment the dial is hovering on the danger zone. The water is fine - as is the central heating downstairs.
Upstairs the radiators are hot at the very bottom but cool/cold above that. I have bled them but there is no rush of air and no liquid comes out.
when the heating is first put on there is a sound coming from the upstairs radiatiors which sounds like water rushing. The sound eventually stops.
The boiler is about 2.5 years old.
Thank you for any help you can give.

David Norwich, February 2009