The preferred wood for a stove is wood from hardwood trees i.e. Ash, Beech, Birch, Blackthorn, Elm, Eucalyptus, Hawthorn, Hazel, Hornbeam, Maple, Oak, Rowan, Sycamore, Wild Cherry, Willow, Alder, Apple, and Pear.
Hardwoods are from slow-growing deciduous trees & the logs have a greater density than softwoods which are from evergreen trees i.e. pines/firs/spruces. Hardwood logs give a greater heat output – up to 50% compared to softwoods.
Different varieties of hardwood have different attributes – Oak, Beech, Ash, Birch, and Elm give the best heat output, fruit trees also provide a good heat output.
For optimal performance, wood should be as dry as possible (moisture content 20% or less); damp wood uses heat to evaporate the water in the wood, producing less heat from the fire and more condensates in the chimney.
Trees felled in winter months have an average moisture content of about 50%, trees felled during the summer months will have an even higher moisture content of around 65%.
Wood needs to be “seasoned” before burning so that energy isn’t used to dry the wood out during combustion. Wet wood produces less heat but more importantly, it causes tar deposits in the chimney.
Wood should be “seasoned” outdoors for at least 18 to 24 months. Wood should be stored off the ground with plenty of space between the logs to allow air movement & with the top covered to keep rain & snow off the wood.
As a guide, wood which is well seasoned makes a distinctive ‘clack’ rather than a dull ‘thud’ when banged together. Other indicators of a seasoned log include the bark cracking and peeling and splitting of the wood across the grain.
We personally recommend the use of kiln-dried wood. Kiln dried logs are dried to an average moisture content of 20% and are recommended for immediate burning on all wood burning appliances. These logs provide the ultimate clean burn with maximum heat output. Our recommended supplier is Certainly Wood.
Seasoned wood gives approximately 50% more heat output than the equivalent volume of unseasoned wood, this means fewer logs to provide warmth & a reduction in the number of condensates/tar inside the stove and chimney. Condensates are a leading cause of chimney fires.
The Forestry Commission has a free guide to choosing & drying logs (PDF format), for a copy click here (opens in a new window) and the Solid Fuel Association has a guide to Wood and Multi-Fuel wood here (opens in a new window).