In reply to GrahamD:
Agree about the flue seal - mine needs doing.
I have a multi fuel one so I tend to run it mahoosively hot using coal every now and then to burn off some of he crap inside, then use seasoned logs the rest of the time.
Try to make sure you use the right sort of wood, as anything green or unseasoned can generate resins which will glog and as another poster said, ignite.
If you get a big one like mine you can immolate an entire person in one evening. The only gve away is the white smoke but I just told the people opposite I was electing a pope.