How Wood Stoves Work

Today’s wood stoves can complement almost any décor -- even that of a modern condo.
Today’s wood stoves can complement almost any décor -- even that of a modern condo.
­iStockphoto/Dave Raboin

­What says, "This feels like home" to you? For many people, it's the image of a roaring fire. The glow of the dancing flames represents the perfect combination of tradition, beauty and coziness. It doesn't matter how many strides the home heating industry has made; few families want to gather around the furnace to open their Christmas stockings.

However, fireplaces are notoriously inefficient -- many of them actually make the rest of the house colder [source: EPA]. If you're concerned about heating bills or energy efficiency, you may have resigned yourself to the idea that the fireplace is only for special occasions.

A wood stove may be a fantastic solution. Wood stoves have evolved quite a bit from their potbellied ancestors. Today's wood stoves are clean and efficient, and ha­ve several environmental arguments on their side:

  • They use cheap, renewable local fuel.
  • They do not rely on petroleum.
  • They produce far less pollution than a fireplace (although even a certified wood stove produces higher emissions than a natural gas stove). [source: EPA]

­However, a wood stove is only as efficient as its installation. A proper installation considers the house's heating requirements and uses the natural movement of heat and air to get the most from the stove. A careless installation, on the other hand, might mean that your wood stove is no better than a fireplace.

This article answers all your burning questions about wood stoves: how to install them, how to put in a stovepipe and how to protect against house fires and other dangers.

Wood Stove Installation Specifications

First things first: get professional help with your wood stove installation. Problems may not always show themselves right away. However, when a problem does arise, it could be in the form of a house fire. To find a reputable professional, check with the nonprofit organization National Fireplace Institute (NFI) [source: EPA].

You must have a chimney for every stove. If you're installing a stove where you used to have a fireplace, you'll need to know how the old chimney was constructed before you attach the stovepipe. If your house is older, the chimney may not be up to current safety codes.

Placing a wood stove depends on the layout of your home and the lifestyle of your family. Like any space heater, a wood stove heats its direct surroundings, so it works most efficiently if you place it in the space where you spend the most time. A wood stove heats best when it's in the middle of the room [source: Wood Heat Organization]. You'll need to think about the way you use your space and the tradeoffs you're willing to make.

Before you place any stove, you must know its minimum clearance requirements. Stove clearance -- the minimum safe distance between a wood stove and surrounding walls and floors -- depends on several factors:

  • Are the walls and floors combustible?
  • Is the stove is certified? Any new stove must be certified by law, which means it meets certain safety requirements. Antique stoves or home-built stoves are likely uncertified.
  • What is the stove made of?
  • Are you willing to install heat shields on combustible walls?
  • Where do you live? There are different clearance requirements in the U.S. and Canada, and the requirements can vary by municipality as well [source: Wood Heat Organization].

Don't place a wood stove in the basement, where it will lose heat to its immediate surroundings, especially if basement floors and walls are poorly insulated. Using a basement stove to heat the upstairs of your home can often result in overfiring -- building bigger, hotter fires than necessary -- which can damage the stove [source: Wood Heat Organization].

Stove size and room size go hand in hand. A stove that's too large will overheat the room. One that's too small will not provide enough heat; or you may find yourself firing the stove so much that you damage it.

You'll also need to install a floor pad around your stove. For more on floor pads, as well as some tips on protecting your walls, go to the next page.

Protecting Walls and Floors from Wood Stoves

You'll need to install a noncombustible floor pad surrounding the base of the stove for a minimum area. Like clearance areas, this minimum is specified by local law. Both the U.S. and Canada require at least 18 inches (45 cm) of pad in front of the stove door and 8 inches (20 cm) on the other sides [sources: Hearth, Wood Heat Organization].

The pad isn't designed to protect your floor from overheating but to ensure that no stray sparks or embers from the stove set the floor on fire. The floor pad can be brick, concrete, slate, ceramic tile or another noncombustible material; in most cases, it may not be installed on top of carpeting. The Wood Heat Organization recommends setting the floor pad so that it's flush with the surrounding flooring -- you don't want to remove a fire hazard but create a tripping hazard.

If your walls are combustible, you can install a shield on a wall to reduce the stove's clearance area. Like the floor pad, the shield should be made of a noncombustible material, such as sheet metal. How it's mounted and what sort of clearance the stove will still require depends on your local building codes, but it's fairly standard for the shield to be on spacers, 1 inch (2 cm) from the wall [source: Hearth].

Another way of reducing a stove's clearance area and still protecting walls is to install a rear heat shield on a stove. This option is not available for every stove, however, as the heat shield must be custom-made for the stove in question [source: Hearth].

Remember, the risk of fire doesn't end with heat shields and floor pads. Fire safety is not just a matter of the surrounding construction materials but also what's in the room. Don't store kindling or wood within the clearance area. Keep blankets, throws, curtains, rugs, cleaning rags or other combustible fabric away from the stove, too. And avoid storing chemical cleaners anywhere near the clearance area.

Finally, even if you've taken all these precautions, you could still damage the walls or floor if you constantly overfire the stove. Extreme heat melts metal, after all, and your heat shield -- while it's very strong -- is only meant to stand up to certain conditions. Burn wood rather than paper, and don't build larger fires than you need.

OK, so you've protected everything from the fire. Now, where does the smoke go? Read on.

Stovepipe Installation Tips

The venting system, or stovepipe and chimney, is one of the most im­portant components of your wood stove installation. A well-installed pipe makes all the difference between an efficient stove and an ornamental one.

Some common ways homeowners run into problems:

  • Retrofitting an old chimney: Frequently, old chimneys are too big for today's wood stoves. That means the amount of air they draw is not proportional to the amount of heat the stove produces. A too-big chimney means you'll burn more wood than you need, and likely spend more time than necessary on fire maintenance. You'll need to install a "liner" stovepipe within the chimney. It should run the entire length of the chimney, and nowhere along its length should it be any bigger than the stove's exhaust opening. But -- before you go jamming pipe up the chimney -- you should know how the chimney was built, and what sort of insulation it contains. The heat produced by a wood-burning stove is different from the heat produced by an open fireplace, and your chimney may not be up to the task without some work.
  • Setting the stovepipe to minimum height requirements: A short chimney may look nicer (though that's a matter of opinion), but it may not supply an optimal draft to the stove. Work with a professional to figure out the right stovepipe height for your stove.
  • Running too much horizontal stovepipe: A venting system works best when it's vertical. Some homeowners, rather than create chimney holes in the roof, run stovepipe out windows or through walls. But this is a very bad idea.
  • Running the stovepipe along an exterior wall: This isn't a safety issue so much as an efficiency issue. The stove will heat more of the house if the pipe travels up along an interior wall, so all the heat from the pipe stays in the house.
  • Not installing a vent to the exterior: This one should be obvious -- it's a good idea for the exhaust to wind up outside your house.
  • Creating too many twists and turns: Venting systems should be direct and straight. Twists and turns in a stovepipe invite the buildup of creosote, and that raises the risk of fire [sources: EPA, Wood Heat Organization, Chimney Sweep Online].

As always, a professional can help you get the stovepipe right. On the next page, we'll look at another good reason to consult a professional -- the safety risks of wood stoves.

Dangers of Using Wood Stoves

The dangers of wood stoves come in two main categories: smoke and fire.

If you have a certified wood stove that was installed by a professional, the smell of smoke is a sign that something is amiss. Smoke in the house can lead to respiratory problems for the occupants. It can also be a sign of graver danger. A certified wood stove should never smell like smoke [source: EPA].

A stovepipe or chimney that doesn't draw properly creates a risk of carbon monoxide poisoning -- and you can't smell a carbon monoxide leak. If you don't have a smoke detector or a carbon monoxide detector in your home, you should install both, pronto. Your local fire department can show you how.

Chimney fires tend to happen when creosote -- a toxic, inflammable residue -- builds up in the chimney. This is more of a danger with old stoves and chimneys than with new. New stoves are required to have low particle emissions; these limits greatly reduce creosote buildup. But you should still perform yearly maintenance and cleaning. You can find a certified chimney sweep through the Chimney Safety Institute of America [sources: ATDSR, EPA].

Floor and wall fires should be preventable as long as you adhere to clearance requirements and install floor pads and heat shields as needed. But you can reduce your fire risk even more by doing the following:

  • Never burn logs made of compressed sawdust and wax, which are designed for open fireplaces.
  • Never burn painted or chemically treated wood, which will release toxins.
  • Never use kerosene, lighter fluid or other fire-starting chemicals.
  • Never let a fire smolder (if you need less heat, build a smaller fire, not a slower-burning one).
  • Burn only seasoned wood (ideally, wood that has dried outdoors for at least six months; it should sound hollow when you knock it against another piece of wood, and the wood grain should have separated a bit at the ends).
  • Regularly clean out ash and place it in a noncombustible receptacle outside your house.
  • Keep combustible household materials (rugs, curtains, towels, paper, etc.) outside the stove's clearance area.

[source: EPA]

Don't let these considerations deter you from installing a wood stove. Installed professionally and used properly, a wood stove can be a fantastic, economical, eco-conscious and energy-efficient addition to your home. Just take the necessary precautions, and you can enjoy one of the oldest -- and most beautiful -- forms of heat.

To learn more, visit the links on the following page.

Related HowStuffWorks Articles


  • Agency for Toxic Substances and Disease Registry. "Creosote." 2002. (Accessed 2/26/09)
  • Chimney Sweep Online. "Sweep's Library: Whuff's the Deal?" (Accessed 2/26/09)
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  • Environmental Protection Agency. "Cleaner Burning Wood Stoves and Fireplaces: Where You Live." October 7, 2008. (Accessed 2/26/09)
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