Paliva a energie
We recommend that wood for heating purposes is as dry as possible. Maximum power output and the longest possible life-span of the boiler is obtained if you use wood that has been in storage for at least 2 years. In the graph below, the energy contents of wood, with respect to water contents is shown. The energy contents decline very rapidly with increased water contents.
Wood with 12 - 20% water contents has got the specific energy 4 kWh / 1kg wood
Wood with 50% water contents has got the specific energy 2 kWh / 1 kg wood
- Dependence of the fuel heating value on water content in wood
|Type of wood||energy contents in 1 kg|
Fresh wood heats and burns badly, smokes extensively, and markedly shortens the life-span of the boiler and chimney. The power output from the boiler decreases up to 50% and the fuel consumption doubles.
The required fuel for our boilers is brown coal of walnut size. Alternative fuels are e.g. briquettes. We recommend that coal for heating is less homogeneous and has got low sulphur contents. Smaller grained fuel types should only be put on the cinders, and only in small amounts.
Briquettes from wood and from straw
Ecological briquettes from wood are manufactured from wooden waste through pressing the contents together, without chemical additives. There are lůot of producers in Czech Republic but the quality of briquets differes. Good quality briquets do not split during burning. Splitting briquts can be burned only mixing with log wood or brown coal. Never burn them separately. The splitting briquets choke the nozzle or rotating grate.
Pellets are a new type of fuel produced via a similar procedure as wooden briquettes from waste wood, i.e. by pressing. White pellets, made from soft wood without bark, are considered pellets of quality.
For the Atmos boilers, pellets of the diameter O 6-9 mm are used.
Other pellets made from cereal straw or sorrel are an option for the future. However, it is necessary to develop new appliances for such fuels, on which we are working.
Comparison of costs of heating with various fuel types (as at 1.1.2008)
|Fuel||Mean fuel heating value||Mean fuel price 1.11.2008||Mean efficiency and type of boiler used||Annual fuel consumption (consumption = 120 GJ and heated space volume = 370m3)||Total costs of a heating season in CZK|
|Wood||14,8 MJ/kg||500 ,- CZK/
piled cubic meter
|ATMOS gasifying boiler
21 piled cubic meters
|Classic boiler (65% efficiency)||12,5
28 piled cubic meters
|Brown coal||18 MJ/kg||2800-3400 CZK/t||ATMOS gasifying boiler
|7,9 t||22.120 - 26.860,-|
|Classic boiler for other fuel (65%)||10,3||28.840 - 35.020,-|
|Pellets||18 MJ/kg||3000-4500 CZK/t||ATMOS gasifying boiler
|7,4 t||22.200 - 33.300,-|
|Wooden briquettes||18 MJ/kg||3000-4500 CZK/t||ATMOS gasifying boiler
|7,9 t||23.700 - 35.550,-|
|Classic boiler (65% efficiency)||10,3 t||30.900 - 46.350,-|
|Natural gas||33,7 MJ/m3||1253
|Classic boiler (90% efficiency)||3960 m3||52.153,-|
|Accumulation electricity||3,6 MJ/kWh||1,66 CZK/kWh||98%||34 010 kWh||56.457,-|
|Direct heating electricity||3,6 MJ/kWh||2,16 CZK/kWh||99%||33 670 kWh||72.727,-|
|Extra LTO (light fuel oil||42 MJ/kg||15 - 19 CZK/kg||90%||3180 kg||47.700 - 60.420,-|
|Propane-butane||46 MJ/kg||17 - 23 CZK/kg||90%||2900 kg||49.300 - 66.700,-|
|Electricity (direct heating, accumulation)||Monthly bill according to circuit breaker rating (189,- až 508,- CZK)|
|Natural gas||Monthly bill according to selected consumption (86,- až 202,- CZK)|
|Propane-butane||Regular pressure vessel inspections|
|Brown coal||Ash collection fee|
The real costs of heating of gasification boilers are in practise even lower then non-gasification boilers. It is caused by easy regulating way of gasification boilers.