I'm in a new house, and I just convinced the lady of the domicile that we should cut some of our energy bill by heating with wood. There is a wood stove that seems to have been lightly used and kept in good shape, but when I removed the stove from the piping I realized that the liner going up the chimney is oval. I've never seen or heard of oval liners and the local stores don't carry oval brushes. Any tips on what I should be using to clean it?