For all its charm and economy, wood heat has one serious drawback: Burning wood can coat the inside of your flue or stovepipe with a tarlike substance commonly called creosote.If enough of this stuff builds up, it can ignite, and the result is a roaring blaze in your chimney.

I've never had a chimney fire, but friends who have tell me it's a frightening experience. The blaze in the flue roars with such intensity that you tend to lose your composure, along with your ability to deal with the situation. What should you do if you're faced with this situation?

First, call the fire department. Most chimney fires will die out harmlessly if the chimney is sound, but the fire department would much rather send a few men over to keep an eye on things than send a whole company to put out a house fire you thought you could prevent.

Next, try to suffocate the fire. With a stove this is easy: Just close the draft control all the way. A fireplace presents problems because it has no intake control, only a damper. If you close the damper you'll just fill the house with smoke, force yourself outdoors, and ruin visibility for the firemen when they arrive.

Best bet is to soak a blanket with water, then hold it over the fireplace opening with the aid of a helper. Hold the blanket firmly in place, since the draft will tend to pull it into the fireplace.

Do not pour water into fireplace or stove: It may crack metal or masonry, causing more trouble you don't need. If you have a spare hand, send him outside to watch for burning debris rising out of the chimney. He can wet down the roof with a garden hose if one is handy (most likely it won't be during the heating season). If you're lucky there will be a thick layer of snow on the roof to provide protection from flying embers.

When the firemen arrive, they may simply monitor the fire until it dies, or they may drop a flare down the chimney to smother the flames. They'll also check your walls and roof near the chimney, looking for signs of overheating. They may even punch a hole in your wall to take a closer look.

Then, if all is in order, they will leave, advising you to keep an eye on the area near the chimney for a few more hours. And they will probably suggest that you clean your chimney more often in the future.