Howdy all.  I am new to the site but not to burning wood.  I currently have a Fisher Grandma Bear that heats my garage and a Lilly add on in the house.  I will be moving shortly into one of my rentals as I am selling the current home.  I have a central masonry chimney in the "new" house.  My question is looking at liners it appears some are nothing more than a one piece flex pipe.  So is there a reason you can't just drop several pieces of single wall pipe in and achieve the same effect?  I plan to install the Fisher in the basement attached to the masonry chimney and expect to have to install a liner of some sort.  Although I haven't inspected the chimney yet to see if it is workable or not.  Just trying to do some homework.  So I guess what I am saying is:  School me on liners.