THE BEST WOODS FOR BURNING

Wood is classified as ‘hard’ and ‘soft’.

Hardwoods are mostly, ‘deciduous trees’, i.e. those that lose their leaves in the autumn, e.g. oak, birch, ash, elm, sycamore, chestnut.

Softwoods are mostly ‘evergreen trees’, i.e. those that keep their leaves all year, e.g. pines, firs, spruce, cedar.

The difference is in the density of the wood, with hardwoods having more cells or fibres. However, some evergreens may be harder, e.g. yew, and there are also a number of medium dense woods that don’t fit into this definition.

Firewood tends to be sold by volume rather than weight so it’s important to know what you are buying so that you get the best value.

Softwoods are easier to burn and can create a hotter, more intense fire that pushes the hot air more quickly up the flue/chimney, reducing smoke and condensation. Evergreens like pine and larch contain a lot of resin and pitch that burn extremely hot when dry. This does no harm to the flue/chimney as long as it is dry and properly seasoned as with all wood.

Ideally, therefore, a supply of both hard and soft woods is needed to give better control and to meet all needs.

DRYING WOOD

Wood, which has recently been cut, is still full of sap and moisture. This is called ‘green wood’.

Greenwood will burn poorly and inefficiently, because it has lots of water in its cells. It may be hard to light and if it does it will smoulder, not give out any heat and cause creosote to build up in the chimney. A cut Oak tree may contain enough water to fill six, 55 gallon drums.

Wood needs to be dried to at least 20% of its% moisture content and this is called ‘seasoning.’ The wood should be stored for a season or so, while it dries. Seasoning can be speeded up by storing the wood properly in cut and split lengths.

Wood is composed of bundles of microscopic tubes used to take water from the roots of the tree to the leaves. These tubes will stay full of water for years even after cutting. Splitting the wood after cutting opens up the tube ends so the water can escape. This also increases exposure to the sun and wind to help dry out the moisture.

Well seasoned firewood tends to have darkened ends with visible cracks and splits, it is relatively lightweight and makes a clear “clunk” when two pieces are knocked together. Recently cut ‘green’ wood hand is heavy, the ends look fresher and it tends to make a dull “thud” when knocked.

STORING WOOD

• Keep it off the ground and under cover
• Preferably with open sides so the wind can circulate and help the moisture evaporate
• Cut logs into short lengths, split down the middle
• Use the longest-dried wood first
• Bring into the house to dry out further and keep it in a container in case insects are present

WE ALSO SUPPLY EASILY ASSEMBLED LOG STORES

 

HOW WOOD BURNS

Watching wood burn - seeing the dancing of the flames and hearing the crackling of the wood - is mesmerising, giving a home an inviting atmosphere. Understanding the burning process is essential to maximising the heat, efficiency and life of your stove as well as minimising any ‘exhaust’ products and flue/chimney maintenance.

Modern stoves, use ‘air wash’ and ‘clean burn’ technology to efficiently burn waste gases and to ensure that the maximum heat is generated during this process. The heat being transmitted into the room unlike the traditional open fire where over 75% of the heat is lost up the chimney. A clear sign of burning efficiency is that virtually no smoke is produced.

The burning process has 3 stages:

1. Evaporation - where any moisture left in the wood is burnt away. Burning wood that hasn’t been properly dried, that is ‘seasoned’, deprives the fire of energy that could be used to heat the home. Moist wood also produces lots of smoke.
2. Emissions - during the early stages of burning, the hot air enters a ‘cold’ flue or chimney and condensates. Because of the exisiting residue in the flue/chimney this condensate takes the form of creosote and can be tar-like in appearance. The more moisture there is in the wood, the more creosote is deposited in the flue/chimney and the more inefficient the fire. The hotter the air gases become the more the creosote is burnt along with any other ‘volatiles' in the wood. This generates more heat, maximising efficiency and reducing the emmissions.
3. Ash - this is what's left after burning.

• Using dry wood
• Insulating your flue/chimney so that it heats up easier
• Controlling the air flow, ie the oxygen needed by the fire, acts as a temperature control