By now it's no secret to most people that fireplaces are far from efficient when it comes to heating a home. Hundreds of people have closed off their fireplaces and turned to wood-burning stoves for their greater efficiency. You can easily get four or five times as much heat out of your woodpile.
There are two ways to do it. You can run the smoke stack from your stove directly into the old fireplace opening. That's what I've done in my home, and it's the easier way. Or you can cut a hole into the side of the chimney. This involves more work and more mess.
For the easy way, select a woodstove with a horizontal stove pipe connector lower than the top of your fireplace opening. This lets you run the pipe straight out the back of the stove through the plate you use to cover the fireplace. If the stove is tall, or its pipe connector comes out of the top, you probably won't be able to go through the cover plate.
For the plate, go to a welding shop and buy a piece of 1/8" steel plate large enough to cover your fireplace opening with two or three inches of overlap all around. Have the shop cut a hole in the plate the right diameter to accept a flue collar sized to accept your stove pipe. The hole should be positioned about an inch or two higher on the plate than the pipe outlet on your stove.
Fasten this plate to your fireplace opening with about eight 1" lag screws driven into lead screw anchors set in holes drilled in the fireplace bricks with a carbid-tipped drill. Any hardware store should have the screws, anchors and bit. Before fastening the plate in place, run a fat bead of silicone rubber caulk about an inch in from the edges of the plate, on its back surface. This will seal the plate against the fireplace opening.
To install the stove, first fasten the flue collar to the plate. Use sheet-metal screws or pop rivets. Use some furnace cement (sold at plumbing shops and hardware stores) to seal the collar, then run a length of stovepipe from the stove into the flue collar. Seal both the stove-to-pipe and pipe-to-collar joints with furnace cement. That's it.
Instead, cut a hole into your chimney large enough to accept a flue collar. Best way to make the hole is drill a series of small holes with a 3/8" carbide-tipped masonry bit. Make the holes about half an inch apart in a circular pattern the size of the hole you need for the collar. Then work with a hammer and cold chisel to remove the masonry between the holes, and to finally chip away until the hole for the flue collar is complete. This is slow and dusty work; wear eye protection.
When the hole is complete, use furnace cement to set the flue collar into its hole. Then connect the stove to the collar. You'll need an elbow to turn the pipe into the collar.
Note: When installing any stove, be sure to maintain the proper distance between it and any combustible surface. Your fire department should have a copy of the National Fire Protection Assn. publication that covers this subject. For most radiant wood stoves you'll have to allow at least 36 inches of clearance behind the stove and to the sides. You should also provide some form of heat protection for the floor beneath the stove. A piece of 24-gauge sheet metal will work.