Recently my hot water stopped working after a long expensive time the engineer finally found it was the aqua sensor which he replaced.
However now while the hot water works the central heating doesn't, all it does is heat a couple of radiators while all the others are cold.
I have bled the radiators but they had no air in them, is there a way that there is air somewhere else in the system that is stopping the heating system from working

John, July 2009

I can seem to get on radiator working at a time by closing all other radiators then using the bleed valve bleed the radiator till it gets hot. However one inlet is very hot while the other side is still cold. Is this a blockage in the return system and if so how can I get rid of it?

John, July 2009

Try turning all radiators off except one (start with the furtherst away from boiler) then turn your heating on at maximum. When that radiator gets to full temperature turn another on and continue this until all rads are on. That may be enough to re-establish the flow around the system. Otherwise you may have a blockage.

Ian, July 2009

The radiators that are hot are two upstairs Directly above utility room where the boiler is and one downstairs in the same room as the boiler.

John, July 2009

what rads are hot and what are cold ?
are they the upstairs rads that are cold etc.

hi-spec plumbing & heating (essex, July 2009