Help, I have a duel central heating system solid fuel and oil. we have been using the solid fuel only but got in oil last week but it would not work. It may of had something to do with the big freeze we had here. Well anyway my son told me he heard the tank bubbling in the attic a while ago, and then an hour later by husband told me that the tank was running in the attic and the radiators are all cold. The tank has now been filling for hours, we cant see a leek anywhere, we dont know if there is a burst pipe somewhere if so where could it be as the thaw was only yesterday and we had no problems till now. Please help