I think it was Tony who asked to see what our chimney was like. My wife is the one who usually checks but today I took the cap off the tee and took a picture up the chimney. Here is what I found: By my feelings, it is time to clean. Sure, we could get by longer but not gain anything. So I think maybe tomorrow I'll run a brush up there. Notice there is not black creosote and we like that as that brown stuff is simple soot and a bit of fly ash. For those who don't know, the horizontal section comes out the rear of the stove into about a 2' run. That has a bit over 1/2" rise per foot of horizonal into the tee. Then it is up about 12'. Short? Yes, by all accounts it should now work but it does. We put the new chimney up in 2007 when we installed the Fireview. We did clean the chimney after the 2009 burning season (about a cup of soot) so what you see is 3 more burning seasons with no cleaning.