Can anyone help? This is our first winter in our 100-year-old house and it's freezing! The furnace runs constantly, but on cold days it never gets above 64. The furnace is 5 years old, but the duct work goes from small to large to small. Could this be making the difference? It is fieldstone foundation with no real insulation. Also, should I insulate the ceiling so the floor on the room above it is insulated?