This is my first ever post to a forum group. I have been reading the discussions on building storage tanks, burning coal, and using draft regulators on flue pipe. All this information on how to extend or get more out of your wood boiler. I am currently using a Logwood AOB 36W wood boiler. I am currenly building a 575 gallon hot water storage system. (more on that later) My first question is I am using a insulated 6" ss chimney and was wondering if anybody has burned coal with this chimney. I have heard its not a good idea because of corrosion?? coal is acidic?? Also use of a damper in flue pipe?? Manual or automatic?? Any input would be helpful Thank you.