Jonathan Ireland
Vicky... if any radiator within a property is warm at the bottom and cold at the top, it is likely needing aired via the manual air point, this can be done with a brass radiator airing key (these can be purchased at your local DIY store for less than £1.00). If however, the radiator is warm at the top and cold at the bottom, unfortunately there is a bigger problem. You have sludge in your system and various tasks will have to be completed to remedy this. Again, unfortunately, this can be costly. You will have to contact a local Gas Safe Engineer for this. J Ireland Plumber