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The denser hardwoods tend to smoulder more easily when the fire is first lit,
so their flue gas temperature will be much cooler.
Because softwoods like pine and larch contain a lot of resins and pitch, a
popular misconception is that they will fur up the chimney with creosote
more easily than a hardwood like oak. This is not necessarily true at all. It is
not the pitch that is the problem, it's the water IN the pitch. Once the water
in the wood has evaporated, that pitch becomes high octane fuel. When dry,
softwoods burn extremely hot.
There is also the matter of seasoning to be considered. When you buy wood,
it will usually have been cut in the winter of the year you buy it. Hard woods
tend to take longer than softwoods to fully dry out.
Softwoods cut in the previous winter should, with proper storage, be ready
to burn the next autumn, whereas many hardwoods may take a bit longer
than that. Oak, for example, is very slow to dry out and ideally left for two
years. It is also possible to purchase pre seasoned wood or kiln dried wood.
Summarising we can say that it is always sensible to buy this year for next
year’s fuel supply and that it is very handy to have both soft and hardwoods.
You can use the softwoods to start a good fire and you will have additional
control over the fire (in addition to the cookers controls) by adding slower
burning wood to fast ones if you want to leave the cooker without tending it
for a while. Alternatively you can add some fast burning softwood logs to the
slower hardwood logs to instantly revive a fire, which has been neglected.
The Wood Burning Process
Understanding what happens when wood is burnt will enable you to burn
wood in a more environmentally friendly way, reduce the maintenance
required for your chimney and get more out of your wood. There are 3 stages
in the wood-burning process:
Evaporation
When you light the cooker a lot of energy will be needed at first to boil away
any moisture, which is left in the wood. Using energy to drive off excess
water in firewood robs the cooker of energy needed for an efficient and
clean burn. Also, much of the energy wasted in evaporating water is energy
that could have heated the hotplate and oven. This is a waste of wood,
money and effort. The presence of all that moisture tends to keep "putting