Stick your head behind the stove and take s peek up the chimney. You should not be able to see up the chimney. You’re pipe should running up the chimney thru a piece of sheet metal that would have been installed in place of the damper. If no block off plate at least you’ll be able to see how far up the chimney the pipe goes.How is it installed?Is there a block off plate in the chimney,sealed?Does the flue pipe go to top of chimney?