Well i'm about to finish my stove install, i'm putting in selkirk super vent, one 42-64 telescopic double wall to the cathedral box then 8ft of class a chimney everything seems kosher except for the actual connection to the stove collar...can i just slip the double wall over the collar or do i need some type of adapter-the fit is good when i put the dbl wall over the collar-trie contacting englander but no response yet.....