I'm building a Duravent Triple Wall chimney for use with a NC-30. I've got the through the wall kit and chimney sections from Home Depot. I've got to put a 30 or 15 degree bend in the chimney but cannot find the kit anywhere local. I'm in Vermont. Would rather not have to buy from an online vendor but it is looking that way. Also I wanted to confirm that there is an adapter available to go from the triple wall chimney to a double wall interior pipe. Or does the triple wall terminate in the thimble? Thanks for any help.