Fuel: Crucial to Successful Wood Burning

 

The quality of the firewood that you burn is the key to convenient, efficient and safe use of a wood burning stove. Wet wood and pieces of the wrong size and shape for your stove can be frustrating when lighting, burn inefficiently and damage your stove, or even worse cause a dangerous chimney fire. Planning, seasoning and storage of the wood you intend to burn is crucial to you making the most out of your wood burning stove.

Tips on buying good firewood

• Ask friends and neighbours who burn wood for recommendations on reliable suppliers.

• Shop around and select the supplier who seems most reliable and comes with the best recommendations.

• Do not order wood over the phone. Visit the supplier so you can inspect the wood.

• Look for wood that is clean. Sand or mud on firewood makes it less desirable.

What are the best tree species for firewood?

All wood is chemically similar, it is the density that influences its behaviour in the fire and its value as firewood. Dense hardwoods like maple and oak have a higher energy content and so release more heat. They also produce long-lasting fires and coal beds. Softer woods like pine, spruce and poplar are less dense, burn faster and do not produce a long-lasting coal bed when burned.
Traditionally, hardwoods have been the preferred firewood, although softer woods are often used through the months of Spring and Autumn. Newer wood burning stoves can function well with a wider variety of wood species because of their better control of the combustion process than conventional stoves.

Hard Woods (long burning) Ironwood Rock elm Hickory Oak Sugar maple Beech Yellow birch Ash Red elm Red maple Tamarack Douglas fir White birch Manitoba maple Red alder Hemlock Poplar Pine Basswood Spruce Balsam Soft Woods (shorter burns)

Density of Common Tree Species   Here is a list of tree species commonly used for firewood, sorted from hard woods to soft woods. Trees at the top of the list have the most energy per cord, while those toward the bottom of the list have the least energy per cord. Although they are less dense, the softer woods can make excellent firewood for spring and autumn because they make heat control easier and don't tend to overheat the house.

Length

The length of the pieces must be suitable for your stove. Shorter pieces are easier to handle and preferable to pieces that are too long for the appliance. Pieces that are even slightly too long can make fire stoking difficult or impossible. Pieces should be at least 7.5 cm (3 in) shorter than the fire box size. Even if a stove fire box is big enough to take long pieces of firewood, shorter pieces are usually preferable for ease of handling and fire maintenance. Good quality firewood is a consistent length. Lengths varying more than 5 cm (2 in) are a sign of poor quality and may cause problems in loading the appliance. For convenient handling and stoking in most wood stoves, firewood is best cut into pieces 35 to 40 cm (14 to 16 in) long.

Diameter

Large pieces of firewood tend to smoulder for a long time when placed in the fire, whereas smaller pieces ignite quickly. Small pieces are better for small fires in mild weather. Even in cold weather each load should be made up of a few small pieces that will ignite quickly and some larger pieces that will burn steadily for several hours. 

Tips for stacking and storing firewood

• Stack the wood in separate rows in an open location where the sun can warm it and the wind can carry away moisture. Do not stack unseasoned wood tightly in an unvented storage area.

• Do not allow firewood to lie on the ground for more than a couple of days before stacking - mold and rot can set in quickly and damage the wood.

• Stack the wood up off the ground.

  
  

The top of the pile can be covered to keep off rain, but do not cover the sides.
Softer woods like pine, spruce and poplar/aspen that is cut, split and stacked properly in the early spring will be ready for burning in the autumn. Extremely hard woods like oak and maple, and large pieces of firewood, may take a full twelve months to be dry enough for use. Drying may also take longer if you live near the sea.

How to tell if wood is dry enough

The most effective way to check the moisture content of the wood is to use a moisture meter, this will give you an accurate percentage of the moisture in the wood, only if it is dry enough should it be used as firewood. If you do not have a moisture meter, there are a few ways to tell if wood is dry enough to burn efficiently.

• Cracks in the end grain can be an indication of dryness, but may not be a reliable indicator. Some wet wood has checks and some dry wood has no checks.

• The wood tends to darken from white or cream colour to grey or yellow as it dries.

• Two dry pieces banged together sound hollow; wet pieces sound solid and dull.

• Dry wood weighs a lot less than wet wood.

• Split a piece of wood. If the exposed surface feels damp, the wood is too wet to burn.

  
  

If in doubt, burn some. Dry wood ignites and burns easily; wet wood is hard to light and hisses in the fire. 

In the autumn, store the wood away from moisture

When the firewood has dried in the sun and wind, move it to winter storage. The area should be dry and fully sheltered from rain and snow. Large amounts of wood should not be stored inside houses because of the risk of mould growth, which can contaminate the air with spores. However, a small amount of wood stored inside can give it time to warm to room temperature before burning.

Where possible, use firewood from a sustainable source

Try to buy your wood from someone who uses good forest management practices. Environmentally sound forest management involves thinning out dying and damaged trees and less desirable species. To support sustainable forestry practices, use wood from a blend of species. Burn the softer woods, such as pine, poplar and aspen, in the spring and autumn. These are the ways you can help to ensure that wood is a sustainable energy source for home heating.

How to prepare your own firewood supply

Burning wet wood is one of the biggest issues we see with woodburning (the other is bad chimneys). Your wood burner can only operate efficiently and emit low emissions if the wood you are burning has about the right moisture content. Properly seasoned firewood has moisture content of less than 20 per cent.

Signs of poor performance related to wet firewood include:

• Difficulty getting a fire going and keeping it burning well

• Smoky fires with little flame

• Dirty glass

• Rapid creosote buildup in the chimney

• Low heat output

• The smell of smoke in the house

• Short burn times

• Excessive fuel consumption

• Blue-grey smoke from the chimney

  
  

In short, burning wet wood is frustrating, wasteful and potentially dangerous. Many of these problems can be eliminated by burning properly seasoned firewood.
Seasoning wood is not just a matter of cutting your wood and throwing it into a pile. Dry wood is the result of specific actions you take. Moist wood, will prevent your heater from performing to its full potential. This is particularly true of modern DEFRA approved stoves which perform extremely well when burning the right fuel.

Properly seasoned wood has another important but less obvious benefit. If you cut and pile firewood right away, mold will not have time to grow. Mold, if it allowed to develop, will escape into your home's environment when you bring the wood inside. Mold is an undesirable (although almost inevitable) component in modern homes and comes from many sources in addition to firewood, but minimizing its growth and circulation improves comfort and reduces allergic reactions. Stacking and drying firewood before mold has a chance to grow is a good plan.

Here are four simple guidelines to follow to get the best supply of wood:

1. Cut the wood to length

The wood you have purchased or cut yourself should be the right length for your stove. This is usually about three inches shorter than the firebox width or length, depending on how you load the wood. In general it is better to have wood a little shorter than perfect rather than longer, first to avoid having to force too-long pieces into the stoveand second because shorter pieces are easier to handle and quicker to dry.

2. Split it to the right size

Next, split the wood to the proper size for your burner. For most efficient wood stoves, this is usually no more than six inches measured at the largest cross sectional dimension. A range of piece sizes is best so that when kindling a fire or reloading on a coal bed you have some smallish pieces that will help you achieve the desirable instant ignition. A selection of sizes from three to six inches in diameter for wood stoves and an inch or so larger for furnaces will probably serve you well.

Keep in mind that firewood only begins to dry seriously once it is cut and split to the right size because in log form the moisture is held in by the bark. So, when buying wood, ask when the wood was cut split and properly stacked to get an idea of how ready it is for burning. For this reason, experienced woodburners like to get their wood in the early spring so they can manage the drying process themselves.

3. Pile in a single row exposed to the sun and wind.

If wood is to be below 20% moisture content when you burn it in the winter, it must have the moisture removed. The only practical way most people can do this is to allow the sun and wind to dry the wood for them.

With this in mind, the wood should be piled in a place where the sun can warm it and the wind can blow through it. As the sun heats and evaporates the water from the wood pile the wind will carry it away. If you don't have enough space to dry your wood along a fence row, you may be tempted to stack a few rows together, but be sure to give some space between rows for the sun and wind to penetrate the stacks. 

4. Allow the wood to dry for at least six months

Most people who split their wood and stack it in well-spaced rows find that they can dry their wood in about six months. If you have your wood stacked in early spring it should be ready to put away for winter's use by October. However, it may need longer than that if you live close to the sea and/or use very dense wood like oak, which is notorious for taking a long time to dry. If you burn hardwood, it is wise to process or buy it in the autumn for use the following autumn. That way you'll be sure of having properly seasoned wood.

 

The most important rule for preparing good firewood is:

Cut, split and stack the wood in early spring and allow it to stand in the sun and wind all summer