How can I fix my potterton floor standing boiler?

I'll assume the F&E cistern is above the level of the top rads.
If you bleed them and air comes out until they are full, then they refill with air a day or so later, you have a problem with air being sucked into the system, the configuration of the pump/cold feed/open vent need to be corrected.

OR:
If they won't bleed or fill, the cold feed from the F&E is blocked and will need to be cleared (messy job).

Carefree
January 2011