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Home Technology
Become a conductor

Our BRUNNER home technology is practical, easy to use and full of benefits for the user. See what the abbreviations EAS, EOS and USA means and how you will enjoy using these "little helpers".

Secure guarantee extension now

Register your BRUNNER product within the first three months and you will receive a further warranty extension in addition to the usual BRUNNER warranties.


Wood burning

Taking a closer look at the process

Flames dance, it crackles, cosy warmth spreads when wood burns. What we humans perceive as so pleasant is a chemical process. The oxygen from the air mixes with the carbon and hydrogen from the wood (wood is bound carbon as a solid matter) and energy is released in the form of heat and light. A combustion process always takes place in three phases: Drying, degassing, oxidation.

What happens in the drying phase?

Wood contains water. When the temperature in the fireplace insert rises to about 100 °C, this water starts to evaporate. The logs shrink and crack. Firewood should have a residual moisture content of less than 20 percent, i.e. it should be thoroughly dried. If it is wetter - you can tell by the clearly audible hissing when it evaporates - more heat, i.e. energy, must be used in the combustion process.

In our blog post you can find more information on correct heating.


The burnout phase/oxidation is the actual combustion

When the volatile components of the wood have burnt off, the combustible gases are released in the next stage at 600 to 1300 °C, reaching the remaining approximately 30 percent thermal energy. The fire flames are now short and translucent. Once oxidation is complete, only ash remains. Good and clean combustion leaves fine, white ash. If larger amounts of unburnt fuel, coal or soot particles are visible, this is indicative of incomplete combustion.

Specialist tip

During the degassing phase, most of the firewood's calorific value is released, namely around 70 percent. The flames are particularly strong, yellow and blazing. All that remains of the original wood at this stage is the carbon skeleton.

Klaus Leihkamm, Head of craftsmen consultation & customer service


These articles might also interest you

Further articles on the topic of heating with renewable energies can be found here in our blog posts.

About Brunner
29. August 2018
The name BRUNNER stands for a company with a passion for stove construction, fireplace construction ...
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