Question: I have purchased a Lopi Answer fireplace insert. The chimney sweep installing it originally told me that my chimney could handle the necessary 6 inch liner with insolation and had given me a ballpark price. Just recently, he now says he has to use a 7 inch ovalized liner, also insulated, in order to fit properly in the chimney, for about $200 more. The 7 inch would then adapt to the required 6 inch round at the stove. My flue tiles are 8-13 but he says are smaller at the top(?). Will the Lopi insert work as well or have any problems with the slightly larger cross section of the 7 inch ovalized liner? How will the draft be effected? Wouldn't a 6 wrapped liner fit in a 8x13 chimney flue? Answer: You will not have any problems with the oval 7" insulated...should work fine! Some 8*13s are as small as 6" or so in the inside, so it is very possible that a wrapped 6" will not properly fit into there. The insulated flue is definitely a better job, but many people have installed the stainless liners without insulation. Depending on your climate, chimney construction,location, etc...this arrangement might be more than sufficient.