Many solid fuel appliances are now multi-fuel and can burn both wood and coal. These include open fires, stoves, roomheaters, cookers and freestanding boilers. The manufacturers’ specification will tell you what you can burn; and especially important if the appliance has a boiler, the average output that you can expect by burning the different fuels.

Some appliances are manufactured solely for burning wood, They will have no bottom grate. However, some can be converted to burn coal by fitting a grate. A grate must be used when you are burning coal and smokeless coal, because these fuels produce more ash than wood fuel. The grate allows the ash to fall away from the fire bed.

You will find information on a selection of manufacturers and importers of wood burning appliances in our links section. Wood burning grates and appliances can be purchased from many stove shops, fireplace showrooms, or selected builders’ merchants. They can also be obtained through heating engineers. Purchasing on the internet or though a warehouse may be perfectly satisfactory so long as you understand the level of technical assistance and support is likely to be less than through the other routes. We would always recommend you consult a HETAS Engineer prior to purchasing an appliance. They will be able to advise whether the chimney you have is satisfactory and whether the proposed appliance is suitable for your heating requirements. Visit the HETAS website, www.hetas.co.uk for a list of HETAS Registered Engineers. Details of your nearest appliance showroom can be obtained by telephoning the Solid Fuel Association on 0845 601 4406.

Exempt Appliances
The following appliances are presently exempted appliances under the Clean Air Act:
(To check later additions to the list or to see if you are in a smoke control area go to www.uksmokecontrolareas.co.uk).

MORSO OWL

WOOD FUELS

Logs
The most common form of wood fuel at the moment is logs. These will usually come from local sources and can be brought from a variety of outlets – e.g. coal merchants, farmers, tree surgeons. It is important the logs are dry and well seasoned. Burning wet or unseasoned wood is less efficient and can cause harmful build up of deposits in the chimney over a very short time. Thick coatings of creosote or resinous material can cause chimney fires, or prevent the chimney functioning properly. This can allow harmful fumes to escape into the dwelling. Efficient burning is achieved by setting the appliance to burn fast after stoking. This will ensure that all the gases are fully burned. Only set to slow burn when all wood has been reduced to charcoal and ash. Newly added wood set to burn slowly creates smoke and creosote in the chimney. The stove should not be banked up with logs for overnight burning. A bright fire which has turned the wood into charcoal should be left with the day’s ash, no secondary air and minimal primary air.

If you buy logs which have not been seasoned, you should store them under cover but open to allow free air circulation for at least a year. Some logs may take 3 to 4 years to fully season. Bring the fuel into the house a few days before you want to use it to get it as dry as possible. Wood from different trees has different heat values The table below provides a useful comparison. Wood fuel has typically less than half the calorific value of coal and smokeless fuel, so you must be prepared to use a greater volume of wood to heat your home or room, unless you use both wood and mineral solid fuel.

Under the Weights and Measures Act, coal and smokeless fuel have to be sold in defined weights, which makes it easy for you to compare the cost between suppliers. Unless there is a local statutory instrument in force, there will be no such statutory weight for deliveries of wood. The logs and wood are usually sold in “nets” or by lorry load, so take care to check the amount you can expect to get for your money. Fresh felled wood weights about one tonne per solid cubic metre but will lose up to half its weight when it becomes fully air dried, so find out for how long the wood has been seasoned before delivery.

If you burn wood, you should have your chimney swept at least twice a year. Do not burn any painted or treated wood. Treated or painted wood will emit chemicals which are potentially damaging to health and the environment. This also applies to MDF and chipboard.

Wood Pellets
Wood pellets are used on specially designed stoves. Pellets are typically made from timber waste from sawmills. The wood goes through a fairly lengthy process of transformation before it is finally extruded as hard pellets. In spite of the processing, the fuel is still carbon neutral and so is less harmful to the environment than other fossil fuels. For commercial undertakings, as with any wood fuel, wood pellets do not attract climate change levy tax.

There are at present a limited number of pellet producing plants in the UK although there is some encouragement to produce from local sources. Some pellets are being imported in the meantime. The pellets for domestic roomheaters and boilers are being supplied in prepacked bags, usually 10kgs in weight, which makes them a handy size to store and load into the hopper. For the larger boiler models, pellets can be delivered in bulk, but an appropriate silo must be available, connected to the boiler. At the moment most of the pellets will be supplied by the stove shop that markets the boilers, but see our links page below for other suppliers.

It is critical to ensure the pellets for domestic stoves are of good quality. European standards are presently being drawn up but in the meantime be aware that pellets generally come in two sizes and the 6mm ones are most common for use in roomheaters/stoves. Good quality pellets will maintain their integrity through the handing process and be made from virgin wood. You should not use wood pellets made from reclaimed wood. It may contain harmful chemicals.

Wood and the Environment
All fossil fuels (coal, anthracite, oil, gas, lpg and wood) 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 in your house. Wood fuel is carbon neutral. It absorbs as much carbon dioxide in its growth as it releases when it is burnt. For this reason, the installation of wood fuel appliances are treated more favourably in Building Regulations.

Typically, consumption figures for the average house for different fuels produce the comparisons in carbon dioxide emissions per week as shown in the adjoining table:

Grants
Under the Government Low Carbon Buildings Programme, selective grants are available for the installation of renewable energy equipment in both domestic and commercial properties. The amount available is limited and capped each month. The grants are available for the installation of wood pellet roomheaters and boilers and for the larger wood chip systems. Visit www.lowcarbonbuildings.org.uk.

There is also a reduced rate of VAT at 5% on the purchase and installation of wood boilers. The definition of a wood boiler is strictly limited and does not apply to any boiler that is available as a multifuel model. For further details of when the reduced rate is applicable visit www.soliftec.com

Other Organisations
For information on Smoke Control Areas, exempt appliances and fuels go to www.uksmokecontrolareas.co.uk.
For information on biomass fuel and other renewables visit the National Energy Foundation website
www.greenenergy.org.uk Tel 08908 665555.
The Biomass Energy Centre is a one-stop shop for information and advice about all aspects of the use of biomass,
including woodfuel, for energy. www.biomassenergycentre.org.uk
Renewable Energy Association is a lobbying body representing producers and suppliers of renewable energy in the UK. www.r-e-a.net
Centre for Alternative Technology (Machynllech ) www.cat.org.uk.