Obed, I don't burn wood for heat, but your photos scared the livin' poo out of me.:shocked: You've burned only one season and your chimney was an accident waiting to happen. I think you are lucky to have had some smoke back up into your house. I ran out and looked at my fireplace vent after seeing your pictures. I burn oak exclusively and most of it a very hot fire, but my chimney tiles are 13" x 18" and must take awhile to get really hot. All I ever see is thin black soot coating. Do you think you may have clogged that chimney due to your original problems with your insert? I'm thinking of an insert so I can get some benefit from all the available firewood on my place. Those photos of yours sure will make me take the installation seriously. I'm going to put an insulted stainless duct up my flue even if it is only 10 years old. Thanks for posting that sobering evidence that installation, dry wood, and burning technique are so important.