Wood fuel for biomass boilers

Wood heating systems are offered for a wide variety of wood fuels. See below for details of the properties of this type of fuel and how it should be stored.

Wood storage

The combustion of damp wood is not only uneconomical, it can also lead to high emissions and tar deposits inside the chimney stack due to low combustion temperatures. Wood reaches its highest calorific value after being seasoned for at least three years in a sheltered location.

Here are a few tips:

  • Split round logs with a diameter of 10 cm or more
  • Stack the logs in a ventilated and preferably sunny spot underneath a canopy
  • If possible, stack logs with generous air gaps to enable flowing air to absorb the dissipating moisture
  • Stack logs on support timbers so moist air can escape
  • Never store freshly cut wood in a cellar, as air and sunshine are required for seasoning. However, dry wood can be stored in ventilated cellars.

Pellet properties

Only 100 percent untreated wood remnants are used in the manufacture of wood pellets to ENplus and ENISO 17225-2 standards. This raw material is waste matter created by the wood processing industry in large volumes through planing or sawing.

Fine grained wood remnants are compressed under high pressure and formed into pellets, i.e. pressed into a cylindrical shape. The fuel is stored and handled in a dry state. Completely dry storage conditions are absolutely essential. This is the only way to guarantee optimum and effective combustion.

Pellets are offered in packs and in bulk. In their loose form, pellets are transported by silo tanker and pumped into the storage room via a hose system. If an oil heating system is to be completely replaced by a new pellet heating system, the room in the cellar used previously to store fuel oil is ideally suited for this purpose.


Storage and supply systems for wood pellets

Storage and supply systems for Vitoligno 300-H and Vitoligno 250-F


Questions regarding wood boilers

Viessmann is aware of its responsibilities towards the sustained protection of the environment. Our company philosophy and products have been designed with this duty in mind.

Can anyone heat with a wood boiler?

Viessmann wood boilers are so convenient to use that they can supply practically any detached house or apartment building with heat. One important requirement is a dry storage room, as the residual moisture in the wood is one of the crucial factors influencing the combustion quality. Conversions, for example of the chimney stack, are generally not required. Wood heating systems from Viessmann are also a perfect companion for oil and gas heating systems.

Which is better – heating with logs or pellets?

Logs are the perfect choice for those who can obtain the fuel themselves, for example from local forestry operations. Wood needs to be seasoned correctly, in other words stored until it has the lowest possible residual moisture content. In addition, a heating water buffer cylinder is required to ensure a continuous supply of heat.

Pellets are made from sawdust, created under pressure. Due to their low residual moisture content they have a high calorific value. Pellets are easy to deliver and store. Supplying and dosing them out to the wood heating system is automatic and convenient.

Where can I obtain wood fuel?

Wood fuel, especially pellets, are now standard for most fuel merchants. Similarly to fuel oil, they are "pumped" into the storage room. This is accomplished quickly and without much effort. Many sawmills and wood processing enterprises also offer pellets. You can obtain logs at favourable prices from forestry operators or farms with forestry enterprises attached.