BURNING WOOD
Firstly lets consider our environment.
All fossil fuels (coal, anthracite, brown coal, peat, oil, gas and lpg) emit carbon dioxide when they are burnt. This carbon dioxide increases the greenhouse gases in the atmosphere, which contribute to global climate change. It is, therefore, very important to think about ways of reducing these emissions. This can be done by ensuring that your heating system is efficient, well maintained and incorporates adequate controls. You should also undertake other energy saving measures, such as increasing the insulation of your house. Wood fuel is carbon neutral. It absorbs as much carbon dioxide in its growth as it releases when it is burnt.
The table below shows typical carbon dioxide emissions per week for different principal fuels used in the average house.
ELECTRICITY 130kgs (generated by fossil fuels)
COAL 120kgs
OIL 90kgs
GAS 70kgs
WOOD NIL
The De-composition of wood, like all living things, has a limited life span after which it dies and decomposes back to the soil. Did you know that a tree releases as much Carbon dioxide when decaying as it does when burned? Therefore, it makes perfect sense to harvest this free energy.
The composition of Wood
The chemical composition of wood cannot be defined precisely for a given tree species or even a given tree. Chemical composition varies with tree part, (root, stem or branch) type of wood, (ie normal, tension, or compression) geographic location, climate and soil conditions.
There are two major chemical components in wood: lignin(18-35%) (phenolic substances) and carbohydrate(65-75%)(cellulose substances). Both are complex polymeric materials. Minor amounts of extraneous materials, mostly in the form of organic extractives and inorganic (ash) are also present in wood (usually 4-10%) Overall wood has an elemental composition of about 50% carbon, 6% hydrogen, 44% oxygen and trace amounts of several metal ions
The ash content from the burning of wood will depend greatly on the material associated with wood such as nails, screws, stones and earth.
The Calorific Value
The standard calorific value for wood is given as 15GJ/tonne at 20% moisture content, wood nominally has a calorific value of 19GJ/tonne with 0% moisture
[Compare Anthracite @ 35GJ/tonne, Lignite @21.9GJ/tonne, Peat @20GJ/tonne and Waste Paper @16GJ/tonne dry weight]
It is perceived that most wood species have a similar ‘element' composition, but their ‘densities' may vary, particularly hardwoods to softwoods and this is what may affect the perceived calorific value where fuel measurements are made on a ‘volume' basis.
When you choose wood for your stove, ALWAYS BURN DRY WOOD. Wood burns best on a bed of ash, so do be careful to retain some when de-ashing. Dry wood means that it has most definitely not more than 18% moisture content. Wood to be used as a fuel should be logged, chopped and stored in a sheltered but airy site for an absolute minimum of 12 months and preferably 24 months. Wood naturally dries at the rate of 25mm" per year so a 300mm round will take 6 years to dry to the centre.
Do not be tempted to stack wet wood on or around the stove believing this will dry the sap out of the wood. A 300mm log takes approx 8 weeks in a kiln to dry to 18% moisture - so the odd hour or two on or by the stove only increases the likelihood of burning your house down!
Freshly cut green wood - ie wood that still has sap in it - is dangerous to burn. It will cause a chimney to choke with wood tar in a few weeks with a grave risk of a chimney fire resulting. In any case, burning sap wet wood is pointless. It produces far less heat, maybe as little as 10% of that of dry wood.
Treat any bought in wood as wet unless its history is known.
Do not burn wet wood with solid fuel as a very aggressive acid is created, which is lethal for the stove, chimneys and flues.
Tar is caused by burning wet wood. It is brown/black in colour and may be liquid. It has an offensive smell. On the sides of the stove, flue and chimney it resembles a black sticky 'chewing gum' and can eventually block the flue ways. When it ignites, it can cause a chimney fire and be highly dangerous.
RECOMMENDED SOLID FUELS FOR WOODWARM STOVES
All Woodwarm Fireview Multifuel stove will burn coal and some smokeless fuels as well as:
Brown coal ‘Lignite' sold as compressed briquettes (Union Briquettes). A European peat like coal widely used for power generation in Europe, not suitable for smokeless areas, but a good easy fuel.
Peat, rarely sold as fuel in England - not suitable for smokeless areas, but useful if you can get it.
Naturally smokeless Anthracite - use large nuts and small nuts. The rocky cinders from Anthracite can cause even the best riddling grate problems, but it is a good fuel.
Homefire and Homefire Ovals, manufactured smokeless.
We use this for our testing. It is a good fuel and easy to handle.
Housecoal. This is dirty fuel to handle and to burn. It needs to be burnt on a high heat with a good combustion air mix to stop a lot of tar deposits. Clean flueways often, tarry glass will tell you if you are not burning hot enough.
Other Fuels. Be aware that cheap solid fuel is likely to be high in petro-coke (coal derived from chemicals). This fuel is likely to be destructive to the structure of the stove.
Always burn dry Fuel.
Always de-ash frequently (twice a day)
However, if you have any queries consult your Approved Coal Merchant Scheme member for further types and availability. The Solid Fuel Association helpline will give it to you - Tel No 0845 6014406
Fireview stoves are suitable for use in a Smoke Control area so long as you burn a smokeless broad based long flame fuel.
Do experiment to find the best one for you, or mix them if you wish.