Boiler Upgrade Scheme vs ECO4: which grant is right for your home?

The Boiler Upgrade Scheme and ECO4 are the two main funded routes to a warmer, cheaper-to-run home in Great Britain, and they do different jobs. The Boiler Upgrade Scheme pays upfront capital grants of up to £7,500 towards a heat pump, and £5,000 towards a biomass boiler, in England and Wales only¹. ECO4 is a supplier-funded obligation worth £4 billion that delivers insulation and heating measures to homes in Great Britain, aimed at low income, vulnerable and fuel poor households².

The single most important rule is that they cannot be combined. Funding from the Boiler Upgrade Scheme and ECO4 cannot be blended for the same measure or included within an ECO4 project⁴. A household therefore picks one route for a given measure: a heat pump through the Boiler Upgrade Scheme, or a boiler, central heating or insulation package through ECO4.

The two also run on different clocks. ECO4 is due to end on 31 March 2026⁵, while the Boiler Upgrade Scheme has a published closing date of 30 December 2029 and installer guidance stating it has been extended to 2030¹. Which scheme fits a home depends less on preference than on tenure, fuel, EPC and whether the household meets ECO4's low income and vulnerability tests.

What each scheme offers in the UK

ECO4 is the fourth iteration of the Energy Company Obligation, which began in January 2013 and is currently in its latest form⁸. It is worth £4 billion and delivers energy efficiency and heating measures to homes in Great Britain². Its stated objective is to reduce fuel poverty by improving the least energy efficient housing stock occupied by low income, vulnerable and fuel poor households, and it works through whole house retrofits rather than single measures⁹.

The Boiler Upgrade Scheme is a different instrument entirely. It came into force on 1 April 2022 and launched on 23 May 2022, providing upfront capital grants towards approved heat pumps and biomass boilers in England and Wales¹⁰. Ofgem administers it on behalf of the Gas and Electricity Markets Authority¹². It is a cash contribution to a single installation, not a whole house programme, and it carries no income test.

That difference in design explains most of what follows. ECO4 is means-tested and measure-rich; the Boiler Upgrade Scheme is universal within its territory but narrow in what it will pay for. A household on a low income with a poor EPC and an old boiler is squarely in ECO4 territory. A household that can fund most of a heat pump and wants the capital contribution is in Boiler Upgrade Scheme territory. The two overlap only in the sense that both can improve a home's energy position, never in the same project.

For the wider landscape of funded routes, including devolved schemes, see home energy grants.

What each scheme will and will not fund

ECO4's measure list is broad. It covers boiler upgrades to non-renewable and renewable heating systems, repair of a broken heating system, replacement of a broken efficient heating system, first time central heating, electric storage heater upgrades and repairs or replacement, connection to a district heating system, heating controls, solar PV, wall, roof, floor and loft insulation, draught proofing, window glazing and higher performance external doors¹³.

The Boiler Upgrade Scheme funds a much shorter list: air-to-water heat pumps, air-to-air heat pumps, ground source heat pumps including water source heat pumps and shared ground loops, and biomass boilers⁶. Hybrid systems are excluded, and no grant is available for a hybrid heat pump system such as a combination of gas boiler and air source heat pump¹⁴.

Eligibility: who each scheme is built for

ECO4 is aimed at households in fuel poverty or at risk of it, and delivery runs through energy suppliers and their installers rather than direct application⁹. Property conditions matter. Where the existing EPC is a D or E it must be able to be improved to a C, and where it is an F or G it needs to be able to be improved to a D¹⁵. Private rented sector properties face a specific restriction: the replacement, upgrade or repair of a boiler, central heating system or electric storage heater is generally not eligible, except where the replacement is first time central heating, a renewable heating measure or a district heating connection¹⁶.

The Boiler Upgrade Scheme has no income test but a set of technical and property conditions. The property must be in England or Wales, must not be social housing, and the installation must replace an existing fossil fuel or electric heating system¹⁸. The previous system must have been a fossil fuel based system or an electric heating system that does not include a heat pump⁶. Self-build properties qualify for heat pumps only, not biomass⁶. Capacity limits apply: 45 kWth for an individual heat pump system, 70 kWth for a multi heat pump system, and 300 kWth total for shared ground loop systems with each connected heat pump not exceeding 45 kWth⁶.

One condition has changed recently and is worth stating plainly, because older pages still carry the old rule. From 28 April 2026, properties are no longer required to have a valid EPC to apply for the Boiler Upgrade Scheme⁶. Government scheme pages still list a valid energy performance certificate as a requirement¹, so the two positions differ; the newer Ofgem installer guidance reflects the current position. Eligibility detail sits on Boiler Upgrade Scheme eligibility and ECO4 eligibility.

Grant amounts and what each scheme costs

The Boiler Upgrade Scheme's headline figures are straightforward. The standard grant is £7,500 off the cost and installation of an air source heat pump, and £5,000 off a biomass boiler¹. From 21 July 2026, eligible off gas grid properties replacing oil or liquefied petroleum gas heating can apply for an uplifted grant of £9,000 for an air-to-water or ground source heat pump⁶. That uplift is in place until 31 March 2027⁶. Properties that do not qualify for the uplift may still be eligible for a grant of £7,500⁶.

The scheme's budget is finite and does not roll forward. Scheme Year 4, running from April 2025 to March 2026, had a budget of £295,000,000, of which £185,500,000 was spent and £109,500,000 remained as at the November 2025 report²⁰. By the February 2026 report the position had moved to £244,337,500 spent and £50,662,500 remaining²¹, and the monthly update recorded £232,720,000 spent in Year 4²². Unspent budget is not carried over to the next scheme year²⁰. The scheme had an initial budget of £150m per financial year for 2022-2025⁶.

ECO4 does not publish a per-household grant in the same way, because it is an obligation on suppliers rather than a voucher. Its scale is set by the £4 billion scheme value and the target of upgrading 450,000 homes over four years³. One specific cap exists: a broken boiler and electric storage heating replacement cap for efficient heating of 5,000 per year³. Where no published price exists for a measure, costs are installer-quoted.

How the application and warranty position works

The Boiler Upgrade Scheme application is a two-stage process: the installer submits a voucher application, Ofgem issues a voucher, the installer submits a voucher redemption application, and the installer receives the grant payment²⁰. A voucher application is only considered properly made once Ofgem has all the necessary information to assess eligibility and the property owner has provided consent and identity verification¹². The application must be properly made within 120 days of the commissioning date⁶. Only one voucher can be redeemed per property, and a property is not eligible if a previous Boiler Upgrade Scheme grant has already been received for a heat pump or biomass boiler at the same address⁶.

Installers carry the compliance burden. All Boiler Upgrade Scheme installations must be MCS certified¹⁰, and all heating systems installed under the scheme must meet the relevant MCS standards approved and published by the Secretary of State⁶. Installers must keep all documentation relied upon in voucher and redemption applications for six years from the date the application was properly made⁶. Ofgem can conduct site or desk audits at any point after an application, including after grant payment¹⁸.

On warranty, the position differs by scheme. ECO4 guidance covers blended funding with the Boiler Upgrade Scheme, which is the administrative treatment of the two schemes meeting, not a warranty in itself²⁴. The Boiler Upgrade Scheme does not warrant the installation; the grant is a capital contribution and the workmanship and product guarantees come from the installer and manufacturer. Heat pumps funded under the scheme must achieve an in situ seasonal coefficient of performance of at least 2.8⁶, which is a performance condition rather than a warranty term. For the application sequence in detail, see applying for the Boiler Upgrade Scheme.

Scheme status and administration

Both schemes are live, administered by public bodies, and neither depends on a private company's solvency. Ofgem administers the Boiler Upgrade Scheme on behalf of the Gas and Electricity Markets Authority¹², and publishes quarterly and annual reports on its website plus monthly operational updates⁶. The most recent quarterly report covers 1 May 2026 to 31 July 2026²⁵. Enquiries go to the BUS Enquiries team at BUS.Enquiry@ofgem.gov.uk or by phone on 0330 053 2006⁶.

ECO4 sits with the Department for Energy Security and Net Zero and is delivered through obligated energy suppliers, with Ofgem publishing delivery guidance that has been revised repeatedly, most recently in March 2026¹⁶. Supplier administration guidance exists for the failure of an obligated supplier, which is the structural risk in a supplier-delivered scheme rather than a scheme-level one²⁷.

The timetable is the live issue. ECO4 is due to end on 31 March 2026⁵, and government guidance refers to the ending of funding for the Energy Company Obligation scheme¹⁹. The Boiler Upgrade Scheme has a published closing date of 30 December 2029¹, and installer guidance states that as of 28 April 2026 the scheme has been extended to 2030⁶. The two do not expire together, and a household weighing them should treat ECO4 as the time-limited route.

What each scheme means for energy independence

ECO4's contribution to independence is fabric and system first. By funding wall, roof, floor and loft insulation, draught proofing, glazing and doors alongside heating measures, it reduces the energy a home needs before it addresses where that energy comes from¹³. Its whole house retrofit approach is designed to lift the least efficient homes, which are also the most exposed to price movements⁹. That is a reduction in demand, and demand reduction is the most durable form of independence because it does not depend on a fuel source, a supplier or a tariff.

The Boiler Upgrade Scheme's contribution is different: it moves the heating load off fossil fuel and onto electricity, and it does so at the point of replacement. A heat pump funded under the scheme replaces a fossil fuel or electric heating system¹⁸, which removes gas or oil from the property's direct consumption. What remains is dependence on the electricity grid and on a supplier, plus the manufacturer's company for parts and the installer for service. The scheme does not fund a battery or solar PV, so a heat pump household without those remains fully grid-dependent for its heating.

Neither scheme delivers full independence on its own. ECO4 can leave a home still heated by gas, simply using less of it. The Boiler Upgrade Scheme can leave a home electrified but still buying every unit from the grid. The combination that most reduces dependence, fabric first and then a heat pump, cannot be funded by blending the two schemes for the same measure⁴, so households sequence them instead. For how these routes fit the wider picture, see grants and energy independence.