Wood as a Fuel

Wood is an ideal fuel which is in plentiful supply and is renewable. It is important that  the wood is dry and well seasoned. Burning wet or unseasoned wood is less efficient because much of the heat produced as it burns will be required to drive off the moisture contained within it as steam.

Water vapour combines with other gases and particles going up the chimney and unless the chimney is kept warm the condensation forms a creosote-like substance which hardens to form tar on the surface of chimney liners and may seep into brickwork in an unlined chimney. Wet logs cause the chimney to cool and so condensation occurs and a residue is formed.  The chimney may become completely blocked with this residue allowing harmful fumes to escape into the dwelling. The volatile residue can ignite causing a dangerous chimney fire.

You would need to burn around three times as many unseasoned logs to achieve the same heat output as well seasoned or kiln dried logs.

For good quality fuel we recommend Firewood Bristol

To ensure an efficient burn:

  • Always test the moisture content of the wood before you burn it. No more than 21% is recommended
  • Begin burning with a small hot fire and add to it slowly
  • Allow plenty of air into the fire to keep it blazing brightly
  • Do not allow fires to slumber at low temperatures
  • Reload your fire frequently with small amounts of timber to maintain a hot burn
  • Never burn old painted or chemically treated wood
  • Make sure that the room is well ventilated
  • Have your chimney professionally swept at the recommended intervals and ask for a certificate.
split logs
wood fire

To ensure an efficient burn:

  • Freshly cut wood will have a moisture content of up to 50%. Before it is suitable for burning that should be reduced to between 15% and 21%
  • Correct storage is the key to successfully drying your logs. Ventilation is the most important consideration
  • The logs should be split as this has the effect of maximizing the exposed surface area which ensures that each piece will dry out much faster
  • You should stack the logs in such a way that air is able to freely circulate around them
  • Provide some form of roof over the pile and leave the sides open
  • Stack the logs on a pallet or something similar to ensure they are not in direct contact with the ground
  • Criss cross the ends of the stack to maximize airflow
  • You should be able to achieve a moisture content of about 15% within a few months
  • A moisture meter will give you an accurate indication of the moisture content of your logs.

    When wood burns incompletely it not only harms your chimney and the environment but also your wallet.

Carbon Emissions

Wood fuel is virtually 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 is currently treated more favourably in the building regulations.

Smoke Control Areas

The Clean Air Act allows local authorities to designate smoke control areas which place legal restrictions on combustion and the use of certain appliances and fuels. If you wish to burn any type of wood fuel and you live in a smoke control area, you may only do so if you burn wood on an “exempt” appliance.

A list of appliances which are currently exempted by DEFRA under the Clean Air Act may be found here.

To find out if you are within a smoke control area, follow the link to the relevant authority shown below.

Bristol Council
South Glos