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Biomass

​Wood-fuelled heating systems, also called biomass systems, burn wood pellets, chips or logs to provide warmth in a single room or to power central heating and hot water boilers.

A stove burns logs or pellets to heat a single room – and may be fitted with a back boiler to provide water heating as well. A boiler burns logs, pellets or chips, and is connected to a central heating and hot water system. A wood-fuelled biomass boiler could save you hundreds of pounds a year compared to electric heating.

Affordable heating fuel
Although the price of wood fuel varies considerably, it is often cheaper than other heating options.

Financial support
Wood fuel boiler systems could benefit from the Renewable Heat Incentive.

A low-carbon option
The carbon dioxide emitted when wood is burned is the same amount that was absorbed over the months and years that the plant was growing. The process is sustainable as long as new plants continue to grow in place of those used for fuel. There are some carbon emissions caused by the cultivation, manufacture and transportation of the fuel, but as long as the fuel is sourced locally, these are much lower than the emissions from fossil fuels.

Choosing a wood-fuelled heating system:

Boiler or stove? 

  • Boilers can be used in place of a standard gas or oil boiler to heat radiators for a whole house, and to heat the hot water.
  • Stoves are used to heat a single room, usually in conjunction with other heating systems, but may also have a back boiler to provide hot water.
  • Stoves are not eligible under the domestic RHI unless it is a pellet stove with a back boiler.

Chips, pellets or logs?

  • Chips are used to heat larger buildings or groups of houses.
  • Pellets are much easier to use and much more controllable than logs. Pellet boilers can run automatically in much the same way that gas or oil boilers operate. Most pellet and chip burners use automatic fuel feeders which refill them at regular intervals.
  • Log-burning stoves and boilers have to be filled with wood by hand and require considerably more work. You will need a lot of logs to heat a whole house, but they can be cheaper than pellets if you have a good local supply.

Do you have a local fuel supplier? 

  • Some companies now offer deliveries of pellets anywhere in mainland Britain and Northern Ireland while the supply of logs is more variable.

Do you have space?

  • Wood boilers are larger than gas or oil equivalents and you will need space to store the fuel. This area will need to be somewhere that’s handy for deliveries as well as appropriate for feeding the boiler.

Do you have somewhere to put the flue?

  • You will need a flue which meets the regulations for wood-burning appliances.
  • This could be a new insulated stainless steel flue pipe or an existing chimney, though chimneys normally need lining to make them safe and legal.

Do you need permission?

  • You may not need planning permission, but you should always check.
  • All new wood heating systems have to comply with building regulations, and the best way to ensure this is to use an installer who is a member of a competent person scheme.

Wood fuelled (biomass) heating system (image: energenengineering.co.uk)