Last night was the first time I've ever been nervous about a burn going on in the stove. I loaded the fireview with black birch (I'm into a decent sized bunch from the stack) and as I was checking the stove 15 to 20 minutes later I smelled something off...a burn smell I hadn't smelled before. I had the combustor bypass closed and the combustor was cherry red, stove was around 475 at that point. It wasn't a strong smell but worry took over for some reason. I was wondering...yikes is this what a small chimney fire smells like? I went to the basement and slowly opened the clean out door and could small "that smell" again...but could only hear a faint wind sound. I closed that and went outside to take a look, it was 6 degrees out and not overly breezy...there was some normal smoke coming from the chimney, nothing excessive but I smelled that smell again. No flames coming out of the chimney, no soot on the fresh snow on the roof. I don't know why I got worried all of a sudden and was thinking chimney fire....really it was the smell that I hadn't smelled before. Maybe that's the way Black birch smells as it burns? I always burn a little bit here and there but it always gets mixed in with other woods. Last night may have been the first time I've ever loaded the stove entirely with it, but not really sure. I wish I could describe the smell...it didn't smell like wood smoke...more like a chemical. Again the smell was faint inside and stronger outside when the breeze forced the smoke down to the yard. When my combustor is on I really don't get much smoke from the chimney so there wasn't much but enough. I think I was probably worrying over nothing but figured I'd post it here to see what people think? The roof right now is covered with the snow we just got so I really don't want to go up and take a look. I was up there early December and ran a brush up and down the chimney so it should still be pretty clean.