6 Types of fuel
The basic fuel for the Holz Master boiler are wooden logs and chips. It is recommended to use
wood of deciduous trees, which is characterized by compact structure and high hardness. Calorific
values of individual species of deciduous wood (with moisture content from 15 to 20%) are listed in
the Table 3. Unlike deciduous trees, conifer wood due to contained resins cause formation of large
amounts of soot in the furnace. For these reasons, combustion of coniferous wood is not
recommended.
Wood species
The calorific value of timber
kWh/m
3
kWh/kg
Hornbeam
2200
4,2
European beech
2100
4,2
Oak
2100
4,2
Ash
2100
4,2
Locust
2100
4,1
Birch
1900
4,3
Elm
1900
4,1
Maple
1900
4,1
Alder
1500
4,1
Willow
1400
4,1
Poplar
1400
4,2
Average calorific value of
deciduous trees
2100
4,2
Table 3. Calorific values of individual species of deciduous trees
It is recommend to use wooden chips with a diameter of 70 to 100 mm and a length of 500 mm. It is
recommended to use fuel with a moisture content not exceeding 20%. With the increase of wood
moisture content, its calorific value decreases. Wood moisture content reaches about 15 to 20%
after appropriate drying or after 2 years of storage. Fresh wood is characterized by more than twice
lower calorific value, than its dried equivalent, and during its combustion steam is condensed on the
boiler walls and large amount of soot is formed and deposited in the combustion chamber and the
chimney.
The Holz Master boiler is not designed to burn waste, flammable liquids and any other fuels
not indicated in this manual!
Holz Master Manual
wer. 22/05/2012/EN/V1.0
HKS LAZAR
str.13