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:
- Logs
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. - Pellets
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. - Chips
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.
Types of boiler
There are three main type of biomass boilers for domestic properties:
- Open fire
The most basic example of biomass heating is an open fire. While this is by far the cheapest option, it’s also very inefficient. However, modern wood stoves can come with an integral boiler to provide a highly efficient heating and hot water system. - Log-fed
Log-fed biomass boilers are ideal for homeowners with good access to firewood and are generally cheaper than automated boilers. Although these can be time-consuming as they have to be hand fed, they can prove to be a cost-effective solution for large properties with reduced budgets. - Semi-automatic
Semi-automatic residential biomass boilers are compact in size and have been designed to offer a more aesthetic appearance, making them suitable to be situated in living areas.
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.
The cost of a biomass boiler
For an average property, it can cost between £8,000 and £15,000 for an automatically-fed pellet boiler. This includes installation, flue, fuel store and VAT. However, a manually-fed log boiler system can be slightly cheaper.
The cost of pellets will depend on the method and size of the delivery. The cost can be kept down to approximately £255 per tonne in most parts of the UK if you can accommodate the delivery of several tonnes at a time, by tanker, in bulk.
While logs are usually cheaper than pellets, transporting them can prove costly. An ideal way to save money is to buy a full year’s supply of unseasoned logs and let them season over the course of 12 months – providing you have the room to store them.
How much should you pay?
How much you should pay for a biomass boiler will depend on several factors. The price will vary depending on the size, make and level of automation of the boiler you choose. Manually fed log boiler systems will be cheaper than automatically fed pellet boilers.
| Small manually fed log boiler | £4,000 to £7,000 * |
| Large manually fed log boiler | £7,000 to £10,000 * |
| Small automatically fed pellet boiler | £9,000 to £16,000 * |
| Large automatically fed pellet boiler | £15,000 to £21,000 * |
The above figures can be used as a guide for estimated costs of biomass boilers. For more information, including installation costs, it is recommended that you talk to a qualified HIES installer.
Government Incentive eligibility
Renewable Heat Incentive (RHI)
If you install a biomass boiler, you may be eligible to receive quarterly cash payments over seven years under the UK Government’s domestic Renewable Heat Incentive (RHI) scheme.
The first of its kind in the world, the RHI scheme was set up to encourage the installation of renewable heat technologies.
Please note, the DRHI is now closed to new applications.
Boiler Upgrade Scheme
Recently, Government has announced plans for a new initiative known as the Boiler Upgrade Scheme which looks to reduce the cost of low carbon heating technologies, such as biomass boilers, so that they are more affordable for consumers to buy and run. As part of the Scheme, a £5,000 grant will be available for biomass boilers for those who meet the eligibility requirements. Find out more here.
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).
Finding a reputable biomass heating company
To get a quote from a reputable company click below to search for your nearest HIES member.
Find your nearest HIES memberOn-going maintenance
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.
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