Wood-burning stoves are highly efficient, running at up to 87% efficiency compared with up to 25% for a traditional open coal fire as open fire has to suck a lot of the (warm) air out of the room, and it is replaced by cold air from outside. The most efficient wood and multi-fuel stoves use ‘cleanburn’ technology, introducing pre-heated air into the smoke at the top of the firebox to combust the hydrocarbons in the smoke, resulting in less pollution.
Wood as a fuel is green, sustainable, renewable, and if burnt cleanly can be 100% carbon neutral, as it gives off as much carbon dioxide when burnt as it absorbed during the lifetime of the tree. Most firewood in this country comes from sustainable sources, so for every tree cut down another is planted, and the carbon released from the felled tree will be absorbed by another tree.
You can choose from a wood only, a multi-fuel, or a pellet stove which burns small pieces of compressed sawdust that are automatically fed into the fire. Wood and multi-fuel burners can also incorporate a back boiler supplying heat to radiators or a domestic hot water systems.
Most people use logs, but they should ensure that only 'seasoned' wood (dried under cover for at least a year to reduce the moisture content) is used.
Pellet stoves are available in a range of sizes from small room heaters to larger units incorporating a boiler supplying heat to radiators or a domestic hot water systems. They usually have an integrated fuel hopper which is filled from a bag. Pellet stoves are available from room heaters of 1.5 to 2kW up to around 12kW, above this size a boiler is more appropriate
All pellets are not the same. Many types of biomass can be pelleted including straw, miscanthus, and cotton waste. While these alternative feedstocks can be useful, it is important to remember that different fuels have different chemical composition and burning characteristics. If your pellet stove has been designed and set up for wood pellets, you should only use wood pellets or risk damaging the stove.
Things you will need to consider:
- You need a chimney with a large enough flue to cope with the output you’ll need for your room. If you don't already have a chimney you will need to have a flue installed at the same time. This can cost as much as the stove itself. Even if you do have an existing chimney it may need lining.
- Check the prevailing wind. If it blows back down the chimney you’ll may need to fit a vent to the top of the chimney.
- Are you in a smokeless zone? If you are and you want to burn wood then your choice of stoves will be restricted to approved appliances;.
More info about smokeless areas can be found on the DEFRA site
For further information about all systems visit http://www.biomassenergycentre.org.uk