Boiler Upgrade Scheme requirements for biomass boilers

Biomass is the exception in a scheme built around heat pumps. The £5,000 figure is the biomass grant, while the scheme as a whole advertises grants of up to £7,500, which is the heat pump figure¹. The two amounts sit side by side in the official material, so the biomass figure should be confirmed with an installer before work is quoted.

The rules that matter most are location, emissions and capacity. Biomass boilers are only eligible where the property is in a rural location and is not connected to the gas grid, including where a gas connection has been capped or clamped³. The boiler must be a standalone system providing both space and hot water, must meet emission limits for particulate matter and NOx, and must not exceed 45 kWth⁵.

What the scheme pays a biomass boiler owner

The published grant for biomass is £5,000 off the cost and installation of the boiler¹. The scheme's own summary describes upfront capital grants of up to £7,500 to encourage property owners to replace existing fossil fuel heating, and that higher figure is the one attached to heat pumps². Both figures are given here rather than one being presented as the answer for every technology.

The £5,000 biomass figure has been stable. It appears in the scheme's annual reporting for 2024 to 2025 as the biomass amount from 23 October 2023⁸. Independent guidance repeats the same number, describing a grant of up to £5,000 per installation for biomass boilers in England and Wales, available when a heat pump is not suitable⁴. A consumer body's funding page likewise states that a boiler must have an emissions certificate showing that polluting emissions are kept to a minimum⁹.

What the grant does not do is cover the whole cost. It is a capital contribution discounted from the installer's invoice, not a payment to the householder, and the balance is met privately. Prices for biomass boilers are installer-quoted and the scheme publishes no price list, so no cost range can be given here. For a rural household off the gas grid, the practical effect is a reduction in the upfront cost of moving away from oil or electric heating, while the running cost depends on fuel supply, storage and the boiler's efficiency, none of which the grant controls.

Eligibility: which properties and which heating systems qualify

Biomass eligibility is tighter than heat pump eligibility, and the guidance describes it as available only in limited circumstances, subject to additional location and air-quality requirements¹⁰. Three conditions run together: the property must be off the gas grid, it must be in a rural location, and the boiler must meet emission limits³.

The heating system being replaced matters too. To qualify, a property must be replacing an existing heating system that operates on either fossil fuels or electricity, and properties that have already had public funding for a heat pump or biomass boiler are not eligible⁸. The new boiler must be capable of meeting the full space heating and hot water heating demands of the property, and must provide both space and hot water heating rather than one or the other¹¹.

Biomass boilers must be standalone systems providing space and hot water, and are ineligible on the gas grid, including where a connection has been capped or clamped, and in self-builds⁵. The definition of an eligible biomass boiler was widened to include those with a cooking function, provided the cooking function is integrated and cannot be controlled separately from the heating function of the property¹³.

A property is not eligible if a previous Boiler Upgrade Scheme grant has already been received for installing a heat pump or biomass boiler at the same address⁶. Blended funding with ECO4 is covered in the scheme guidance, so an ECO4-funded measure at the property is not by itself a bar¹⁴. The ECO4 scheme works on different eligibility grounds, and the two routes are compared on Boiler Upgrade Scheme vs ECO4.

The 45 kWth capacity limit and emissions standards

The maximum permitted capacity for an individual biomass boiler system is 45 kWth, the same ceiling that applies to an individual heat pump system⁵. The limit is per system, and it is the figure an installer checks against the property's calculated heat demand before quoting.

Emissions are the second technical gate, and they are set out as certificate limits rather than as design guidance. The boiler's emissions certificate must show that particulate matter did not exceed 30g/GJ net heat input and that NOx did not exceed 150 g/GJ net heat input⁶. The scheme rules require an emissions certificate showing that polluting emissions are kept to a minimum³. The requirements for biomass boilers sit in regulation 10 of the 2022 Regulations, amended by the 2024 amending regulations¹⁵.

The capacity ceiling shapes which homes the grant realistically serves. A 45 kWth biomass boiler suits a larger rural property with high heat demand, which is also the kind of home most likely to be off the gas grid. Above that figure the scheme does not apply, and the installation becomes a privately funded project. MCS certification is the other standard in play: the scheme is installer-led, and installers who are MCS certified can apply for and redeem vouchers on behalf of property owners¹⁶. The MCS biomass technology page sets out what certification covers for the technology⁴.

How the installer-led application and voucher process works

The application is installer-led, with the installer applying for the grant on the property owner's behalf¹. The installer discounts the grant from the invoice, applies to Ofgem for a grant voucher, and redeems the voucher after installation and commissioning¹. It is an installer-led two stage process, which means the property owner's chosen installer applies for and redeems the voucher¹⁴.

Stage one is the voucher application. Installers submit a voucher application, known as stage 1a, where Ofgem checks whether the pre-installation eligibility criteria are met; if the application succeeds, Ofgem issues the voucher at stage 1b¹⁷. Stage two is redemption: the installer submits a voucher redemption application and then receives the grant payment¹⁸. The same two-stage description appears across the quarterly reporting¹⁸.

1. The installer checks the property against the eligibility criteria.
2. The installer submits the voucher application to Ofgem.
3. Ofgem checks pre-installation eligibility and issues the voucher.
4. The boiler is installed and commissioned.
5. The installer submits the redemption application and receives the grant.

Two timing rules govern the sequence. The boiler must be commissioned no more than 120 days before the voucher application is properly made, and retrospective applications are permitted if properly made within 120 days of commissioning¹⁰. Once issued, the voucher must be redeemed within three months for biomass boilers⁷. The scheme requires confirmation that the property owner has consented to an application being made on their behalf²⁰. The application process is described in more detail elsewhere.

England and Wales only: where the scheme applies

Only properties located in England and Wales are eligible for Boiler Upgrade Scheme funding⁶. The scheme is targeted towards domestic and non-domestic properties in England and Wales, and self-build properties are eligible for heat pumps²¹. The government's own evaluation of the scheme records its territorial extent as England and Wales²².

For biomass specifically, the location test is narrower still. Biomass boilers are only eligible where the property is in a rural location and is not connected to the gas grid⁴. Rural properties only, in England or Wales, is how the older property owner guidance put it¹⁴. Householders in Scotland, Northern Ireland and Wales should note that the scheme does not extend to Scotland or Northern Ireland at all, and that separate devolved schemes operate there, covered under home energy grants in Scotland and home energy grants in Northern Ireland.

The rural and off-grid conditions mean the grant is aimed at households with the least grid dependence already. A property with no mains gas connection is not exposed to gas price movements, but it is exposed to whatever fuel it does burn, whether that is heating oil, LPG or electricity. Biomass moves the household onto a fuel it can store on site, which is a form of energy independence, but it substitutes one delivered fuel for another: the wood pellets or chips still arrive by lorry, and the boiler still needs servicing and a flue. The wider picture of grants and energy independence sets out what the scheme does and does not change.

Social housing, self-builds and other exclusions

Properties classed as social housing are not eligible for Boiler Upgrade Scheme funding, and this includes shared ownership properties⁷. The guidance has been expanded to explain what counts as social housing, with confirmation that Right to Buy properties may become eligible once they are privately owned⁵. The social housing position is treated separately.

New build properties are not eligible for the scheme except for certain self-builds¹⁸. Self-build properties are only eligible for Boiler Upgrade Scheme funding for heat pumps, and biomass boilers are not eligible for funding in self-build properties¹⁰. A biomass installation therefore has to be a retrofit into an existing property.

The Energy Performance Certificate position has changed. From 28 April 2026, properties are no longer required to have a valid EPC to apply for the scheme²³. Where a property does hold a valid EPC, the certificate number must be provided¹⁶. The government has said it intends to amend the eligibility criteria to relax the EPC requirement from 2026/27 onwards, adopting a hybrid model⁵. The EPC and insulation question is covered in full elsewhere.

Scheme end dates and budget: how long the funding runs

The scheme's funding has been extended well beyond its original window. The government confirmed funding for further years up to 2029/30 through the Warm Homes Plan in January 2026²⁴. The scheme is scheduled to close at 11:59pm on 30 December 2029¹. Older local authority guidance still describes the scheme as running from 2022 to 2025, which reflects the position before the extension²⁵.

Budget figures have moved over the scheme's life. The 2022 to 2023 financial year budget was £150 million⁶. The final budget for 2024 to 2025 was £180 million²⁶.

Take-up of the biomass element is small. Thirty biomass grants were paid in the quarterly period from November 2025 to January 2026¹⁸. That is consistent with a technology restricted to rural, off-gas properties with an emissions-certificated boiler. For a household weighing the grant, the practical reading is that funding is confirmed for several more years, the biomass share of it is small, and the eligibility conditions rather than the budget are the binding constraint. The Boiler Upgrade Scheme pillar page covers the scheme as a whole, and the grant amount page covers the payment figures.