I live in South Carolina so winters are very mild. We get down in the upper teens at night but that's about the worst. So is it necessary to insulate the liner on a masonry chimney on the outside wall? I was at a dealer today and he said that he never insulates. But then again he told me that no liner at all was OK. just slide the insert in and let it go. From what I've read here there is no way I would not use a liner but can I get away with skipping the insulation? thanks