I am in the process of deciding upon a wood boiler, and am currently looking at the Tarm, Eko, and Wood Gun. I have an unused 6x8 flue in my chimney that I was planning on using for the boiler, whatever one I choose. Should this be ok? I just read a post mentioning lining a clay flue with a round metalbestos type liner, and I suddenly got concerned that this was a necessity, for some reason, on a wood boiler. Any help would be appreciated.