© 2013 Brunner GmbH
User manual IRON DOG 02 (1.1)
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FIREWOOD AND HEATING POWER
The combustion process in our devices has been optimized to enhance their performance and
reduce emissions. You can support our efforts to protect our environment by respecting the following
recommendations for low-emission heating: Use only dry, natural firewood with a water content below 20%
or wood briquettes according to DIN 51 731, size class HP2.
Damp, freshly cut or improperly stored wood has a high water content, therefore does not want to burn,
makes a lot of smoke and gives not much of heat. Use only firewood stored for at least two years in a dry
place with sufficient air circulation. Because dry wood is much more calorific, you can save on fuel costs.
For example: Dry wood has a calorific value of approx. 4 kWh/kg, freshly cut wood only 2 kWh/kg. You will
need twice the amount of wood to achieve the same heating power.
Water content g/kg wood
Calorific value kWh/kg Consumption raised by %
very dry
100
4,5
0
stored for 2 years
200
4
15
stored for 1 year
350
3
71
freshly cut wood
500
2,1
153
Natural firewood (picture left) is the best
fuel for fireplaces, but you can also use
wood briquettes complying to DIN 51 731,
size HP2 (picture right).
How much thermal energy you will get, if you buy
wood by weight?
500 kg freshly cut wood
Water content 50%
500 kg x 2.0 kWh/kg = 1000 kWh
500 kg dried wood
Water content 30%
500 kg x 3.3 kWh/kg = 1650 kWh
500 kg dry wood
Water content 15%
500 kg x 4.1 kWh/kg = 2050 kWh
