Wood and Pellet Boilers  :

Biomass is the general term given to combustible organic material harvested and burnt to create energy.  Most common, in a domestic system are wood logs, wood chips and pellets.

Burning wood is carbon neutral since the CO2 released when burning is equal to the CO2 absorbed during growth.  As long as the wood comes from a source where new trees are planted to replace those that are harvested then there is balance.

The main ways to use wood for heating in the home are.


Stand Alone Wood or Pellet Stoves

These are essentially room heaters where the burning chamber is totally enclosed.  Creating a focal point in a room, typically they have an output of around 7 to 8kW or less and burn logs or pellets.  With an efficiency of up to 80% they offer a marked improvement on open fires that have an efficiency of less than 30% and when not lit offer an easy escape for precious, indoor heat.  There are also stoves available with back boilers for heating water.

Wood and Pellet Boilers                

Burning logs, wood chip or pellets boilers offer a complete central heating system distributing heat via radiators and producing hot water.  The boiler sized for the heat demand of the building and can be used to heat homes, large public buildings and also used for district heating systems.

Pellets are made from sawdust and shavings from sawmills and the best quality come from 100% virign timber with no additives, rather relying on the naural lignin of the wood to act as a binder.  Check that your supplier is harvesting from sustainably managed plantation forestry.  About 6-8mm in diameter and resembling animal feed, pellets are supplied in bags or by the tonne for large quantities.  Dry storage is essential and humidity should not exceed 12%.
Pellet boilers offer the convenience of an automatic feed from a hopper or large storage room and regulated flow of pellets onto a grate where the controlled burning takes place.  The small amount of ash left from burning is expelled into an ash drawer below the grate and can be easily accessed from the front of the boiler for emptying.  How regularly the ash needs to be emptied depends on the boiler and the quality of the pellets.  With weather compensation, built in controller and electric ignition the boiler maintains a constant indoor temperature automatically.  Annual cleaning and servicing is required as well as sweeping the flue.  

Wood boilers require manual feeding on a regular basis with logs which can be up to 0.5m long in "domestic" sized boilers.  The function of the wood boiler is similar to the pellet boiler but without the automation.  Substantial water storage is needed with a wood boiler installation to take care of the heat.  Some of the key factors in determining whether a wood or a pellet boiler is right for your home or building are:
  • Heat demand of the building
  • Level of convenience required
  • Availability of local supply of logs, wood chip or pellets
  • Available storage space for wood fuel and proximity to boiler
  • Practical and planning implications of the required flue
  • You can't live in a smokeless zone

To discuss these and other eco-friendly ways to heat your home and for further details please contact us

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