By Mark Benson, of Bowland Stoves Limited
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Are wood-burning stoves really environmentally friendly?
There is no doubt that wood-burning stoves are more popular today than they ever have been and their popularity is still on the increase. The general public is more aware today that while the purchase and installation of stoves may be top-heavy at the front end from a cost perspective, there are significant financial and environmental benefits going forward. As the cost of gas and electricity increases these benefits will only grow as the years go on.
Are wood-burning stoves really carbon neutral?
There have been many studies in relation to the life of a tree and the carbon dioxide released when it is burnt in a wood-burning stove. In a worst-case scenario, it has been proven that a mature tree will absorb as much carbon dioxide in its lifetime as it will release when burned. In reality the vast majority of trees will absorb more carbon dioxide than they release which makes them even better that carbon neutral. So in effect, replacing a mature tree which has been used to fuel a wood-burning stove with a sapling will begin the cycle again releasing a net zero of carbon emissions into the atmosphere.
The way in which a wood-burning stove works is that the heat is retained within the combustion chamber and slowly radiated out through the body of the machine. The initial combustion process burns the basic wood fuel with the hot gases circulated around the body of the stove. Secondary and tertiary combustion processes are now commonplace in stoves today. The secondary process will burn the hot gases to create even more heat and the tertiary system draws in more air and burns off the majority of waste gas which is left. This ensures that minimum emissions are directed into the flue pipe and up into the atmosphere hence current efficiency ratings for many stoves in excess of 80%.
It is worth noting that the average coal fire has an efficiency rating between 20% and 30% which further illustrates the highly efficient technology associated with wood-burning and multi-fuel stoves.
Burning the correct wood
In theory any wood can be used as fuel for a wood-burning and multi-fuel stove but the wood needs to be dried correctly for maximum efficiency and to prevent damage to the stove. In general, freshly chopped firewood can have a water content of up to 50% which is far too high to use as fuel for a stove. The general consensus is that a moisture content of less than 20% is fine for a stove but anything more will burn less efficiently and can create substances such as creosote which can damage the flue pipe and chimney.
How to season your wood
As a rule of thumb, pine and other softwoods traditionally take between six and 12 months to season correctly. Hardwoods take a little longer with anything up to 2 years required to bring the moisture content down below 20%.
It is advisable to chop logs into more manageable lengths of up to 8 inches in diameter and 18 inches in length - although you can adapt the log sizes to the size of your stove. Once the wood has been cut it should always be stored outdoors with a suitable distance between the wood and any buildings/walls and it should also be raised from the ground with many people using strategically placed sapling wood to do this. Even though the seasoning wood requires some kind of tarpaulin cover over the top, this should not cover the whole log pile, leaving sufficient space for air to circulate and continue drying the wood in both hot and windy conditions. This is very important as tightly covering the wood with no airflow is counter-productive when looking to season wood.
When you believe the wood is ready simply use a moisture meter which will measure the moisture element in the wood. If it is below 20% then it can be used as fuel for your wood-burning or multi-fuel stove although if above 20% further seasoning is required.
Obtaining quality wood
As the cost of running gas and electric heating systems continues to increase so the popularity of wood-burning and multi-fuel stoves continues to grow. In some areas it may be more difficult to obtain quality seasoned wood at affordable prices and unfortunately some people may not have the required space and facilities to season their own wood. The Internet is now playing a greater role in the availability of wood and even if you are struggling to find a supplier in your immediate vicinity, there will be many people online able to assist.
While it may be tempting, you should refrain from using substandard wood, unseasoned wood or wood which has at some point been covered in paint or other substances. The burning of paint covered wood, or other substances, can not only damage your flue and chimney but some of these may create toxic fumes when burned.
"This article was supplied by Bowland Stoves http://www.bowlandstoves.co.uk
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