What's the fastest way to burn wood

Firewood: Tips on storage and regulations on moisture content

The fireplace season is approaching. There are a few things to consider when buying and using firewood. If you use wood that is too damp, you are liable to prosecution.

There is one thing you can rely on: the next winter is sure to come and with it it is time to turn the fireplace on again. If you don't have enough wood in your warehouse, you should take care of the stock now. Where to get wood and which types are best - the most important questions and answers about firewood.

Where do I get the best wood?

"Anyone who uses their fireplace regularly or operates a tiled stove needs a few cubic meters of wood a year," explains Volker Lenz from the German Biomass Research Center in Leipzig. "You don't get very far with bagged goods from the hardware store." It is cheaper to order the wood from specialist retailers or to go to the forester to find the remains of logging. However, with the latter option you have to consider: Freshly felled wood is not suitable for the upcoming season. It is still too damp and has to dry out first.

When can fresh wood end up in the stove?

According to the law, only wood with a maximum moisture content of 25 percent may be burned. This corresponds to around 20 percent water content. Although the value depends on the weather and the type of wood, according to the German Forest Protection Association, freshly felled wood can usually be assumed to have a moisture content of 100 to 150 percent (50 to 60 percent water content). This means: the logs usually have to air dry for one to two years - although hard woods such as oak and beech need longer to dry than soft types such as pine and spruce. Anyone who does not adhere to this regulation must expect fines.

What damage does damp wood cause?

"If the wood is too damp, dark smoke often gushes out of the chimney and there is an unpleasant smell in the air," explains Alexis Gula from the Federal Association of Chimney Sweepers in Sankt Augustin near Bonn. "Because the temperature in the stove drops due to the evaporation of moisture, the wood burns incompletely. Soot and tar particles are produced as waste products, which escape with the smoke through the chimney, but also settle in the stove, stove pipe and chimney." This layer of soot reduces the efficiency of the stove and, worse, it can ignite.

How can I control the moisture content?

There are inexpensive measuring devices. However, expert Lenz says: "They are not always very precise. Many users are also not clear about what they are measuring, the wood moisture or the water content of the wood. The higher the water content, the clearer the difference is." In addition, measurements are often made on the surface of the wood. "Even if the necessary guide values ​​are met there, it can still be too damp inside." So it is better to plan enough drying time in any case.

What is the fastest way to dry wood?

"Fresh wood is first sawn and split before it is piled up to dry in a sunny or partially shaded place," advises Christian Liesegang from the Federal Environment Agency. To prevent insects from nesting in the wood, it must not have direct contact with the ground. A waterproof cover such as a tarpaulin is sufficient to protect against rain and snow. "But it must be open on the sides so that the supply is well ventilated."

Which wood is recommended?

For economic and ecological reasons, local woods should be used for the stove. "The combustion chamber of the chimneys is usually designed for hardwood such as beech and oak. They have less resin than soft types and do not pollute the interior as much," explains Lenz. Spruce and pine are usually less suitable for single-room fireplaces. They cause higher emissions. "Softwood is often used for biomass boilers." The expert recommends paying attention to the corresponding instructions on the packaging when buying firewood. "If it only says logs, it can be mixed wood. Typical examples of hardwood in Germany are beech and oak."

Contaminated wood, for example with paint or varnish residues, does not belong in the oven under any circumstances. "Anyone who burns their old garden fence is committing an administrative offense," explains Liesegang. "Burning paint, varnish and other chemicals that adhere to the wood creates high emissions and toxic substances such as dioxins and furans."

How much wood is there in the stove?

Too much fuel in the chamber is rather counterproductive. "When it gets too warm, many stove owners close the air regulators that provide the combustion air," explains master chimney sweep Gula. The combustion can then be incomplete, which gives rise to carbon monoxide and the stuck and rather flammable soot.

What to do with the bark

Burning the bark can be problematic. "The more bark is burned, the more fine dust is created," explains Volker Lenz from the German Biomass Research Center. Oven owners should avoid it if possible. But nobody has to remove the bark from the wood. However, Lenz advises: "If possible, residual bark that is left over should not go into the oven. It is better placed on the compost." With the exception of oak bark. "Their acid content can be so high that generally usable potting soil can no longer be obtained from the compost. Anyone who intends to do something like this should rather throw oak bark into the ash bin."