I'm interested in installing a fireplace insert and considering installing the chimney liner myself to save money. I know that I need to install a 6" liner with insulation. As a follower of Red Green, I know that if the women don't find you handsome, they should at least find you handy. So I try to be fairly handy. I've read up on these forums and know that I can use an angle grinder and/or reciprocating saw to carve a hole in my existing fireplace damper. I've got a reciprocating saw and am totally comfortable using it. I'm going to get a professional out to clean and inspect the chimney prior to my doing this. I've taken several photos to show you all what I'm dealing with. You can view them here: http://imgur.com/R4h4zZs,ii7i3ua,rMxiAcs,0LFxqUy,tCtx7nf,iN2s2tl My chimney flue is 11.5" x 11.5" at the top. The damper opening is only about 4" at the most, which will require me to cut into it in order to fit a 6" liner through it. I'm not sure if I should cut into the lower or upper edge of the damper, though. I'm thinking I can just order a flexible liner online, for example this one: http://www.osburnwoodstoves.com/product_p/chimney-liner-kit-20-foot.htm, cut through the damper and pass the liner through the hole to the insert exhaust. I've read others mention that you need a block off plate to prevent drafts from coming down the chimney into the home, but I've never welded anything before and am not comfortable with this step. Should I have a professional do this whole operation?