I'm removing this woodstove from my basement and I have a free-standing woodburner that I want to install. I'm going to get the existing flue checked for cracks but I am wondering how I should hook up the new woodburner to my existing chimney. The new woodstove has a 6" round exhaust opening but as you can see from the pics, the existing flue is a rectangular clay and the existing stove looks like it just slid in there and never was fully sealed to the flue. Is there some type of adapter that I can buy or should I run a liner the whole way up the existing flue?