Pellets are small standardised cylindrical rolls comprising 100% natural wood residues such as wood shavings and sawdust. The dried wood residues are ground and compressed into wood pellets under high pressure using special presses. No binding agents or additives are required, and neither are they permitted. Manufacturing wood pellets from dried wood shavings takes about 1% of the energy contained in the fuel, or about 5% if moist sawdust is used. The "liquid wood" therefore has the best energy efficiency of all fuels.
If you use wood pellets for your heating system, you can use the following comparisons as a guide. In terms of calorific value, two kilograms of wood pellets are comparable to one litre of heating oil. For 650 kg of wood pellets you need one cubic metre of space. Thus three cubic metres of wood pellets for your wood pellet heating system correspond to about 1,000 litres of heating oil. Wood pellets, the liquid wood that combines economical space requirements with environmentally friendly operation.
The quality of the pellets is an important factor in achieving optimum operation of the heating system. When buying pellets, make sure that they meet the quality standards of EN ISO 17225-2 A1. For maximum reliability, source pellets from manufacturers with EN-Plus certification (or DIN-Plus, ÖNORM M7135 or UZ38), as they are required to perform ongoing internal quality control. Make your pellet supplier aware of these quality requirements before ordering and seek confirmation upon delivery.
Some visual characteristics of good pellet quality are a shiny, smooth surface, uniform piece size and little dust. Quickly and easily test the quality yourself by throwing wood pellets into a glass of water. Good quality pellets sink immediately.
Diameter: 6 ± 1 mm
Length: 3.15 to 40 mm
Bulk density: > 650 kg/m³
Heat value: > 4.6 kWh/kg
Ash content: < 0.7%
Fines material portion: < 1%
Trees absorb CO2 from the air as they grow. When wood is burned, precisely that amount of CO2 is released back into the air, so it is no higher than it would have been had the tree rotted naturally in the forest. Heating with wood pellets is therefore CO2 neutral and makes an important contribution to climate protection.
The quality guidelines for transport and storage logistics are defined in ENplus and ÖNORM M7136.
Pellets are sold by fuel merchants in the following form:
- for manual filling of the fuel hopper in 10, 15 and 30 kg bags and also Big Bag with approx. 1 tonne on Euro pallet
- For automated room and building clearing in loose form by means of bulk road trailer, quantity as required (offered and delivered in kg)
Pellets must be transported and stored absolutely dry. They swell up greatly if stored in moist conditions. Therefore, the pellets must be protected against moisture during transport, storage and through to combustion. Learn more about pellet storage here.