Man I'd have put in a halon and every other first suppression system known to man into that place with all the stuff he has. Well if it's the main house and nothing is nearby it probably won't hurt much but better safe than sorry and he has his own fire fighters?
It vents smoke to the outside. Unfortunately, if you don't have your chimney chim-chim-cheroo'd often, tar and soot and various other goop accretes into creosote, which is highly flammable and will combust and cause some serious trouble if not immediately dealt with. If you don't clean this out:
I used to make my living in the fireplace business. Chimney fires can reach 3000 degrees Fahrenheit and if you think that's hot, keep in mind that your vitrified clay flue liners are fired to near the melting point at around 2200 degrees when made. Chimney fires often lead to cracked flue liners that if not repaired/replaced will lead to a house fire at some point. I'm glad no one was hurt (even Jar Jar). :behave