Wood log boilers generally burn virgin wood which has been cut and processed into logs. Other clean waste woods such as carpentry offcuts are also suitable. Several questions and important factors when producing or buying your wood, including storage and handling.
Whether buying or processing your wood logs the most critical factor is the wood must be dry. By dry, we mean less than 20% moisture and ideally less than 15%.
Wood will naturally dry in the UK, a little slower in wetter Northern areas but it will still dry to be fuel.
How long this takes depends on the wood itself and the way it has been processed and stored.
Wood is ready to be burnt after about 2 years of being stored in suitable conditions and split during the early summer of use. By two years we generally mean two full spring and summer periods. If however the wood is split and well stored in the first winter it’s possible to be ready the following winter depending on the wood type.
Splitting wood opens the internal surfaces to allow interior moisture to escape through the action of the wind and sun. It also increases the surface area, allowing quicker drying.
The best way to dry wood is to keep it off the ground with a ventilated floor such as a pallet. The top is covered in a waterproof cover ideally black in colour to heat up from the sun and in an open position where the wind can do the most benefit.
The density of the wood changes the time it takes to dry. The tighter the grain structure inside the wood, the longer the wood takes to dry. The moisture exits the wood via these grain lines the natural tubes within the wood: the smaller these tubes, the more challenging to expel the water.
Oak and other hardwoods have small moisture tubes while pine and most softwoods have larger rings which allow water to escape faster.
Simple to operate and ignite
Burns logs and clean wood waste
Correctly sized once or twice per day fuelling
Located in a boiler room simplifies cleaning and maintenance
Very high efficiency up to 92% depending on model
Wood logs can be stored locally to the boiler house
The boiler house can be located remotely to the property to be heated
Can be easily linked with an alternative heating source
The check list
Requires a dedicated boiler room capable of fitting the boiler and accumulator
Requires daily fuelling
Fuelling is undertaken by hand
Requires occasional ash removal
Requires annual maintenance by engineer