The following is an excerpt from an interesting site I found:
"Our home has a large permanent brick chimney that serves our two wood heating/ cooking stoves is quite another matter. For the past thirty years, we have lived in this 90+ year-old, 9 meter (30 ft) one-story square wood frame structure, with an unlined brick chimney rising up from its center to about a meter above the peak of a steep pyramid roof. We blocked off the old fireplace at the base of the chimney and connected above it the flue of a 1922 "Home Comfort" woodburning kitchen cook stove, and in the living room, the flue of a cast iron, space heating box stove. The 6" diameter flue pipe of each stove runs about four feet vertically, and six feet horizontally, to connect to the brick chimney.
During the winter, we run both stoves at full draft to minimize smoke and creosote build-up. No banking the fire at night means re-loading every four to five hours in very cold weather. We take down the stove pipes once a year for cleaning, removing from each about two pounds of hard, brittle, glassy-- to soft fluffy tar/ creosote. The brick chimney itself gathers hard creosote layers that are very difficult to remove, as the roof is too steep to climb, and I can reach only a little way up into it with scrapers from below.
During our thirty-year stay here, we have experienced five or six flue fires-- very scary, very dangerous. Usually, they happen in the middle of the night when we are awakened by a strange palpable roar and the crackle of over-heated stovepipe. If it has advanced far enough, we can see the landscape near our house illuminated by an eerie orange glow from the blowtorch of flame extending several feet above the chimney. Our flue fires always start from a very hot stove, work their way up and along the stove pipe, and into the chimney. With luck, we can stop the progress of the burn before it reaches the chimney by shutting off all air and by cooling the stove pipe with water. If we can't stop it, a full-fledged chimney fire takes over. If we can't put it out, at least we can slow it down. Over the years, fires have eroded the mortar between the chimney bricks. Before we re-grouted the bricks, we could see the orange glow of the raging fire inside the chimney through open cracks between the bricks. We keep a garden hose ready at all times, to keep the roof from catching fire. I also have a chemical torch that is supposed to lessen the ferocity, but have not used it yet. A full flue fire does completely clean out the chimney, so its not all bad, unless it also cleans out the house.
So why the heck don't we fix it? Tear the chimney out and build it right? It would cost less to let the house burn and buy a trailer. Abandoned for over twenty years, "this old house" has feasted colonies of termites, the foundation has hosted lush gardens of moldy dry rot, the ceilings have suffered from leaky roofs, and floors were never level or square. It is a few years older than we are, and it need last only a few years more. The important things-- the family, the forest, and the land-- will still be when we and the house are gone."