Understanding Biomass Boilers

Understanding Biomass Boilers

Biomass systems (otherwise known as wood-fuelled heating), burn wood matter to provide a heat source either for a single room, or an entire heating system

What is Biomass?

Biomass is waste material—mostly from wood—that is used to create heat, liquid biofuels, and electricity. Wood is one of the most natural and sustainable fuel sources available to us, it has a carbon neutral cycle as it releases about the same amount of carbon dioxide into the atmosphere through burning, as it absorbs during growth process. Wood pellets are produced by compression of sawdust or wood shreds to create a pellet that has typically below 10% moisture content meaning pellets have a high volume energy density. They are also clean, consistent and flow easily, making them particularly attractive in domestic applications. 

Biomass fuel offers an economic incentive to manage woodland and improve biodiversity. The fuel has clean burn credentials and super efficiencies as well as the capability to significantly reduce carbon emissions. Although the price of wood fuel varies considerably, it is often cheaper than other heating options.

Why Biomass?

Controlled in a very similar way to an oil or gas boiler, biomass wood pellet boilers can offer super efficiencies in excess of 90% meaning a more viable option for properties particularly in rural areas that currently have an oil or non-gas heating system installed. 

Advantages of a Biomass Boiler system?

  • Biomass boilers are said to be close to carbon-neutral
  • A new boiler can be easily connected to your existing heating system with very little or no disruption to your premises
  • Biomass boilers are very efficient, durable, clean and easy to use, requiring minimal management time

How much could I save with a biomass boiler?

Savings in carbon dioxide emissions are very significant - up to 14.5 tonnes a year when a wood-fuelled boiler replaces a solid (coal) fired system or electric storage heating. Financial savings are more variable - if you replace a older gas heating system with a wood-burning system you might save up to £80 a year, but if you are replacing an old electric heating system you could save as much as £650 per year assuming you are installing pellet central heating in a typical four-bedroom detached house with basic insulation.

Biomass maintenance

Wood fuelled boilers, stoves and room heaters should be kept clean and swept regularly to remove ash. Ash quantities are generally very low (<1% of fuel volume). This is likely to be weekly and never more than once a day. Some appliances particularly boilers have self-cleaning systems built in which will collect ash from the combustion grate and the heat exchanger tubes. If there is no automatic ash cleaning mechanism in place the boiler will need to be shut down periodically so that this can be done by hand.

Some boilers have a mechanism for compressing the ash which reduces the number of times the ash bin needs to be emptied. With automatic ash removal and cleaning of the heat exchanger the only maintenance requirement will be occasional ash removal and an annual maintenance check. If you have a wood burning stove or boiler the chimney and flue pipe must be swept regularly to remove all soot deposits and prevent blockage. It’s recommended that this should be done before the heating season to check that the flue has not been blocked and also at the end of the heating season to prevent soot deposits from resting in the chimney during the dormant period.