Had to stop using my VC WinterWarm Small for a while. Starting to get a lot of "back puffing". This usually tells me that the top 6" of the liner is getting clogged up. Mostly the chimney cap I'm sure, but long and short of it, can't get on the roof until I get some snow melt. Which around here could be a month or so. Getting hammered with snow again today - another 10-12" by this afternoon...