Sounds like the problem is with insulation. You may need to check for presence of any insulation in the walls and perhaps blow some more in. The steel will conduct your heat out even with insulation. I would also check the outside to see if there are any places that need more screws and/or caulking.
Another thing that may help is to make sure the heating system blows directly on the exterior walls. That could keep the condensation down or dried up as it forms. The basic principle of heating is to keep the areas of heat loss warm and the rest of the house will be warm also. That includes windows, doors and poorly insulated walls.