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Wood Heating

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Learn to burn cleaner and more efficiently

Wood heating is the largest source of smoke (fine particle) pollution in Spokane County during the heating season. Stable weather patterns can make matters worse by trapping smoke near the ground during the winter. 

Wood smoke is a complex mixture of fine particles, many of which are toxic and known to cause cancer. Breathing wood smoke can harm everyone, but children are most vulnerable because their lungs are still developing. Also at higher risk from wood smoke are infants, the elderly, and those with existing heart and lung ailments.

Today’s new wood stoves burn much cleaner and efficiently, but how the stove is operated is the biggest factor in how much it smokes. The goal is to see only heat waves or just a wisp of smoke from the chimney.

Chimney smoke – how much is too much?

State law prohibits excessive chimney smoke. Smoke is measured as opacity. Smoke so thick you can’t see an object through it is considered 100% opacity. Smoke is in violation when it obscures an object by more than 20%.

After start-up, check the chimney. If you see more than heat waves, provide more air (open your damper) to the fire.  

Smoky chimneys may also be caused by burning firewood that has not adequately dried. Wood should be split, stacked and loosely covered to dry at least 9-12 months.

Manufactured logs and pellets may be burned in your wood burning device. Burning anything other than natural firewood or manufactured logs/pellets is prohibited under state law.

Buying and installing wood burning devices

Washington regulates the types of wood stoves and other wood burning devices allowed for sale, resale, exchange, or that are given away. They must meet federal EPA and Washington certification standards. 

Use a stove that is EPA certified, the right size for your home, and properly installed. Never install a non-certified wood stove. See EPA’s wood heater database webpage for listings of approved wood burning devices. A permit and inspection is required for installation so contact your city or county building department for details. List of certified wood stoves and wood-burning devices:

Federal emission standards for wood stoves and pellet stoves are now more protective than Washington standards. All other wood-burning devices must still meet Washington standards.

Buying or selling a house with an uncertified wood stove

In some states, removing an uncertified wood stove is required as part of the real estate transaction. Although not required in Washington, it is a good idea to consider replacing old wood heating devices. Grants are currently available to assist homeowners upgrade old wood burning stoves to new, cleaner heat sources, including wood, pellet, gas and ductless heat pumps. Learn more.

Is your wood stove EPA-certified?

During a Stage 1 burn ban (Yellow) only EPA-certified devices may be used, therefore, it’s important to find out if your device is EPA-certified or not. 

  • If your wood stove (free-standing or insert) was manufactured prior to 1993, it probably is not EPA-certified. If it was manufactured in 1993 or later there should be a label on your device indicating EPA certification. This can only be done at the manufacturer level. If there is no label present, the device has not been tested for emissions levels in an approved laboratory setting, and therefore is not EPA-certified.
  • Below is an example of a label that can be found on wood stoves that are EPA-certified. Sometimes the labels are on the back of the stoves.

Temporary burn restrictions & exemptions

We issue temporary restrictions on wood heating and outdoor burning when fine smoke particle levels are rising and expected to continue to rise due to stable weather patterns. Learn more about burn restriction and exemptions if wood is your sole source of heat.

Preparing firewood for more efficient, cleaner burning

Burning clean, dry, seasoned firewood to heat your home saves money, ignites easily, and lessens the impact on local air quality. To burn efficiently, wood should be split, stacked, and loosely covered for at least six to twelve months, depending on the type of wood.

When people have trouble with wood-burning systems, a common problem is that the wood is not dry (or seasoned) enough. Wet firewood is hard to ignite, slow to burn, and creates excessive smoke. Wood smoke contains many chemicals and is harmful to our health when inhaled.

Whether you get your firewood on your property, on public lands, or from an independent firewood seller or retailer, it needs to be seasoned. Seasoned wood has been split and air dried for at least six months (longer for hardwoods). It tends to be dark in color, cracked on the ends, and lightweight, and its bark is easily broken or peeled.

The ideal moisture content for firewood is 15-20%. Spokane Clean Air has firewood moisture meters to loan to interested Spokane County residents, just email your request to LWoodard@spokanecleanair.org.

Steps for well-seasoned firewood:

  1. Wait at least 6 months and up to 12 months for dry firewood depending on type of wood. Hardwoods like oak and maple dry more slowly than soft woods like pine and spruce. To ensure dry firewood, wait at least 12 months before burning. To test, bang two pieces together; dry wood sounds hollow, wet wood sounds dull.
  2. Cut wood to the right length. The wood should fit easily in your woodstove. Make sure it is about three inches shorter than the firebox width or length.
  3. Split wood before stacking. Split the wood to the right width, no more than six inches in diameter. Splitting the wood before stacking increases exposure to air, which improves the drying process.
  4. Stack wood in alternate directions. This improves circulation and further reduces moisture.
  5. Store firewood off the ground. Use pallets or build a woodshed to keep firewood six inches or more off the ground to protect the wood pile from moisture.
  6. Cover the top of the wood pile, but leave the sides exposed. A structure with a roof is ideal, but you can also use a tarp. Remove the tarp to speed up drying in the warm summer months.

For more information, including an easy-to-build woodshed designs, visit www.burndryfirewood.org or https://www.epa.gov/burnwise