Okay, first off I have a super 27 with straight pipe, double wall inside and triple out and total of over 16 ft. This is the 2nd year with this stove (first one was a little steel box with just a small steel plate under opening of flue with a damper on it) so when I was new to running stoves I had a lot of black crunchies on porch and roof (I know why then) but I just noticed for the first time with this stove I had a few also (first time). Flue was swept prior to season and only a quarter cup was there (Jan-april 11) I run my flue no less than 300 on my double wall and stove is run 500-600 not usually any more..glass stays clean, wood is seasoned so what is causing this? I also don't have and wierd sounds in pipe like rice krispies. I am gonna have it swept again here soon as snow melts off roof but I am a little concerned until then..I thought maybe since the moisture from the snow and stove going cold for two days that when it heated back up that what was on cap blew off...at least I hoping that was all...any help would be appreciated..Thanks