Biomass Boilers
Overview
Biomass boilers operate in a similar way to conventional gas or oil boilers, providing reliable space heating and hot water for residential and commercial properties. However, instead of fossil fuels, they use sustainably sourced wood pellets as their primary fuel, offering a renewable and low-carbon heating alternative.
Wood is considered a near carbon-neutral fuel source, as the carbon dioxide released during combustion is broadly equivalent to the amount absorbed by the tree during its growth. When responsibly sourced and managed, biomass heating can play an important role in reducing reliance on fossil fuels and supporting long-term decarbonisation.
In the UK, it is estimated that around 8.5 million tonnes of waste wood are sent to landfill each year. This material could instead be repurposed — where suitable — into wood pellets for biomass boilers or used in other biomass heating systems. Redirecting waste wood in this way not only provides a renewable source of heat and hot water but also helps reduce landfill use and supports a more circular, sustainable energy economy.
How Do Biomass Boilers Work?
Biomass boilers generate heat using a process known as gasification, which delivers high efficiency and clean combustion. This is achieved through a two-stage burn process. In the first stage, wood pellets are burned at temperatures of around 600°C, releasing combustible gases. These gases are then re-burned in a secondary chamber, raising temperatures to approximately 1,200°C.
The resulting hot gases pass through a metal heat exchanger, where heat is transferred into the water used for heating and hot water systems, while the exhaust gases are safely discharged.
In most biomass boiler installations, a thermal store is used. A thermal store is a large insulated tank of water — typically sized at 30 litres or more per kW of boiler output — which acts as a heat battery. It stores hot water generated by the boiler and releases it gradually to meet heating and hot water demand.
The biomass boiler is connected to temperature sensors within the thermal store, allowing the system to operate efficiently and automatically. The boiler fires when the stored temperature falls below a set threshold and switches off once the target temperature is reached. This controlled operation helps optimise performance, reduce fuel consumption and extend system lifespan.
Why use biomass instead of fossil fuel?
The integration of a biomass heating system is generally straightforward, particularly for retrofit projects. In most cases, a biomass boiler can replace an existing fossil fuel boiler, such as oil or LPG, while the downstream heating system remains unchanged. This means existing radiators, underfloor heating and pipework can often be retained, reducing disruption and installation costs.
Key Advantages of Switching to Biomass
Fuel cost savings
Heating with biomass can be significantly more cost effective than traditional fossil fuels. Where there is access to an existing or local wood supply, fuel cost savings of up to 80% compared with oil can be achieved, even after allowing for processing and handling costs. This makes biomass particularly attractive for rural properties, estates and commercial sites with higher heat demand.
Long-term financial benefits (legacy schemes)
Biomass systems installed under historic government support schemes, such as the Renewable Heat Incentive (RHI), continue to receive quarterly payments for eligible heat generated over the scheme’s lifetime. While the RHI is now closed to new applicants, these legacy installations benefit from long-term income streams that help offset capital costs and improve whole-life returns.
Greenio can advise on system compliance, servicing and optimisation for existing RHI-supported installations.
Reduced emissions
Biomass boilers are widely regarded as low-carbon heating systems. The carbon dioxide released during combustion is broadly equivalent to the amount absorbed by the trees during growth, making biomass a near carbon-neutral fuel when sustainably sourced. According to industry data, biomass heating can reduce carbon emissions by up to 96% compared with fossil fuel alternatives.
FAQs
How much space do I need for a biomass boiler?
Biomass systems typically require more space than a gas boiler, as allowance is needed for the boiler itself, fuel storage and often a thermal store. They are therefore best suited to properties with adequate internal or external space, such as rural homes, estates and commercial buildings.
How is biomass fuel delivered and stored?
Wood pellets are usually delivered in bulk by tanker and blown into a hopper or silo, or supplied in bags for smaller systems. Greenio will advise on the most suitable storage solution based on your property, access and heat demand.
How often does a biomass boiler need refuelling?
This depends on the size of the fuel store and usage. Automated pellet systems can operate for weeks or even months between deliveries, while smaller systems may require more frequent refilling.
How much ash does a biomass boiler produce?
Biomass boilers produce a small amount of ash, typically less than 1% of the fuel volume. Ash removal is simple and usually required only every few weeks, depending on system size and usage.
Is biomass suitable for urban properties?
Biomass is generally better suited to rural or semi-rural locations where space is available and fuel deliveries are straightforward. Urban installations may be possible but require careful planning around space, access and emissions requirements.
Why Greenio?
Biomass Heating Expertise
Greenio’s knowledgeable and approachable specialists are on hand to guide homeowners and businesses through every stage of a biomass heating project. We take the time to understand your property, heat demand and fuel options to ensure the right biomass solution is specified for efficiency, compliance and long-term performance.
Qualified, Experienced Biomass Engineers
All Greenio engineers are fully qualified and bring extensive experience in the installation, servicing and maintenance of biomass boiler systems. As a forward-thinking, professional and customer-focused company, we ensure only skilled and accredited engineers deliver our biomass projects.
A Complete One-Stop Solution
From initial assessment and quotation through to installation, commissioning and handover, Greenio manages the entire process. You’ll benefit from a single point of contact throughout, providing clear communication and complete peace of mind.
Customer Service You Can Rely On
Exceptional customer service is central to our approach. We are proud to have received over 100 five-star Google reviews, reflecting our commitment to quality workmanship, reliability and customer satisfaction across domestic and commercial installations.
Quality Assurance & Warranties
All biomass boiler equipment installed by Greenio is supplied with full manufacturer warranties. In addition, every biomass installation includes a 24-month workmanship guarantee, giving added confidence in the quality and durability of our work.
Compliance & HETAS Certification
Where required, biomass servicing and maintenance is carried out by HETAS-approved engineers. This ensures systems are maintained in line with industry standards and, for legacy installations, supports ongoing compliance with Renewable Heat Incentive (RHI) requirements where applicable.
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