The is a natural gas fireplace that uses a flexible double wall exhaust pipe. 7" outer 4" inner (see pictures). It needs to be reconnected to the exhaust in the in the sheeting/siding. How much clearance it requited between the sheeting and the outer wall of the pipe? Hope that make sense.
http://i1238.photobucket.com/albums/ff484/reckless_meanie/IMG_1114.jpg
http://i1238.photobucket.com/albums/ff484/reckless_meanie/IMG_1118.jpg
http://i1238.photobucket.com/albums/ff484/reckless_meanie/IMG_1116.jpg
Thanks,
-Travis