How does biomass heating work?
Biomass heating can be utilised in different ways. In its simplest form, it can comprise of a stove or fireplace to heat a single room, fuelled by burning logs or pellets. The stove can also be equipped with a back boiler to generate water heating.
Properties can utilise a stand-alone biomass boiler, instead of a gas or electric model. These are fed – automatically, semi-automatically, or by hand – with wood pellets, chips or logs.
The hot gas and air produced by burning these materials travel through a flue and pass through a heat exchanger. This transfers the heat to the water used in the property’s heating system.
Choosing a fuel
There are three types of fuel to choose from for a biomass boiler:
A large number of logs would be required to heat a whole house but this can prove cost effective if you have a good local source.
The majority of pellet and chip burners benefit from automatic fuel feeders which top up on regular intervals. Pellet boilers can operate automatically in a similar fashion to gas and oil boilers and are easier and much more controllable than logs.
Wooden chips are the preferred choice when heating larger buildings or a group of properties.
Where to buy wooden pellets or logs?
Some companies now offer deliveries of pellets anywhere in mainland Britain and Northern Ireland while the supply of logs is more variable. It is worth doing your research to find the best supplier for you and you can also ask your installer for advice.
What are the benefits of biomass heating?
There are several benefits to converting your home to biomass heating:
- Cheaper heating – Even though the price of wood fuel can vary, it usually costs less than other heating alternatives, especially if you can source a good local supply. Compared to an old electric heating system, a wood-fuelled biomass boiler could prove up to £800 cheaper.
- As long as your fuel is obtained locally, the carbon emissions are typically lower than the ones from fossil fuels.
What size of boiler do you need?
The size of boiler required for your particular property will be dependent on how well it is insulated, the draught proofing of the building, the lowest external temperature for the region and how you intend to use it. A qualified heating engineer will be able to calculate the size of the boiler needed.
A useful method to use in order to make an initial size estimate for your boiler is to calculate the volume to be heated (in cubic metres) and divide it by 34 (for a reasonably well-insulated house) and this should tell you your boiler size output (in kW).
Biomass boilers require on-going maintenance in order for them to function efficiently.
- Although ash quantities are usually low, biomass boilers and stoves will still need to be swept on a regular basis to remove the ash and keep them clean. The ash bin will need to be emptied about once a week.
- Some boilers benefit from a self-cleaning system, collecting ash from the heat exchanger tubes and combustion grate. However, if this isn’t the case then it will be necessary to shut down the boiler on occasions to perform this by hand. If this isn’t done then the ash can build up and affect combustion conditions. This could lead to the boiler failing and shutting down.
- The only other maintenance requirement will be an annual check. In the case of a wood burning stove or boiler, it’s important that the chimney and flue pipe are swept on a regular basis in order to get rid of soot deposits and avoid blockages.
Biomass maintenance standard
Well maintained boilers and stoves operate more efficiently, which can reduce costs and improve the lifespan of the installation. Regular maintenance also has a significant impact on reducing emissions.
The Microgeneration Certification Scheme (MCS) is the leading standards and quality assurance organisation in the UK for small scale renewable heating installations. To be eligible for Government incentive schemes, such as the Renewable Heat Incentive (RHI) or Boiler Upgrade Scheme, installers must be MCS certified. MCS has created a maintenance standard that is designed to reduce particulates and contribute to the efficient running of the biomass system. Although it is not mandatory to follow this standard for the Domestic RHI, it is good practice. We recommend that your engineer follows this standard when maintaining your biomass system.
For more information on the standard, see here.