I'm getting ready to order some perlite to dump into my chimney and then I got thinking, how is this really going to affect my setup? Right now, I have a 6" liner in a 7"x7" ID clay lined chimney. I know the liner is touching the clay in numerous spots. I'm not sure I will be insulating much more than just the four corners (round liner in a square hole), but I've been thinking that whatever insulation I can get in there should help to keep the heat in the liner rather than soaking into the surrounding tile and masonary. Then I got thinking, will having spots of the liner that are insulated and spots that are not create some kind of negative effect like creating hot spots or something?