I have a brand new thru the wall class a chimney kit made by Air Jet.Its triple wall pipe.I've been looking on craigslist for some good used air jet chimney pipe but so far I haven't been able to find ANY.I'm building a rocket stove mass heater that's going to need about 20 ft of interior pipe .It's going to run out from beneath my rocketstove barrel to a large bench .It will eventually be covered in cob and rock . (thermal mass)I'm going to need another 15 ft or so to run up to the roof thru my chimney kit. I've found plenty of double wall and triple wall pipe on craigslist ,eBay,etc.but no air jet triple wall chimney pipe . MY QUESTION is THIS:Is it possible to buy a conversion kit so I can use a different brand of insulated pipe in the chimney kit I presently have ? I'm right in the middle of building my rocketstove and need pipe before I can go any further with my project.I'm very frustrated at this point and think I may have taken on a project that's just too darn expensive.HELP!