Page type: primary-anchored (mirrors Boiler Upgrade Scheme, SI 2022/565 as amended)
Last updated: 2026-04-05
Boiler Upgrade Scheme (BUS)
The Boiler Upgrade Scheme is a government grant scheme that pays installers to fit heat pumps and biomass boilers in domestic and small non-domestic properties in England and Wales. It is established by the Boiler Upgrade Scheme (England and Wales) Regulations 2022 (SI 2022/565), as amended by SI 2024/524. DESNZ sets the policy and budget; Ofgem administers. The scheme runs from 23 May 2022 to 31 March 2028.
Source file: sources/desnz/bus.md
How it works
Grant flow
BUS is a grant scheme, not a supplier obligation. The chain runs: Secretary of State publishes grant values and budget (Reg 12-13), installer applies for a voucher on behalf of a consenting property owner (Reg 14), Ofgem issues a voucher (Reg 15), installer commissions the plant, installer redeems the voucher (Reg 16), Ofgem pays the installer (Reg 16(3)). The grant reduces the cost to the property owner.
Current grant amounts (published by Secretary of State)
| Technology | Grant |
|---|---|
| Air source heat pump | GBP 7,500 |
| Ground source heat pump | GBP 7,500 |
| Biomass boiler | GBP 5,000 |
| Air-to-air heat pump | GBP 2,500 |
The 2025/26 budget is GBP 295 million.
Grant amounts are not set in the SI itself. The Secretary of State determines and publishes values per Reg 13, and may change them with 28 days' notice.
Who can get a grant
Eligible property (Reg 5): a building (not social housing) in England or Wales that has an existing fossil fuel or electric heating system (not a heat pump), a valid EPC, no previous public grant for heat pump/biomass at that address, and no prior supplier-obligation (ECO) installation. New-build properties eligible only if self-built and not part of a commercial development (Reg 7).
Eligible plant (Regs 8-11):
Heat pumps (Reg 9): new components only (except shared ground loops), max 45 kWth (300 kWth for shared ground loops), Secretary of State-approved standards, minimum seasonal coefficient of performance of 2.8, electricity-driven compressor, air source must not use expelled building air. Must provide space and hot water heating via liquid medium and meet full heating demands.
Biomass boilers (Reg 10-11): new components, max 45 kWth, approved standards, emissions certificate (Schedule 1). Restricted to rural (population under 10,000), off-gas-grid, non-new-build properties only.
Commissioning and voucher timeline
The plant must be commissioned no more than 120 days before the grant application is properly made (Reg 8(1)-(2)). Ofgem may extend this where its own decisions caused delay (Reg 8(3)).
Voucher validity: air source heat pumps and biomass boilers expire after 3 months; ground source heat pumps after 6 months or 31 March 2028, whichever is earlier (Reg 15(2)). Ofgem must refuse all new vouchers after 31 December 2027 (Reg 15(4)).
Installer requirements
Installers must hold Microgeneration Certification Scheme (MCS) certification or equivalent under a UKAS-accredited scheme (Reg 2). Obligations include retaining application information for 6 years (Reg 17(1)(a)), notifying Ofgem within 14 days of any inaccuracy (Reg 17(1)(b)), and providing requested information within 14 days (Reg 17(1)(c)). These obligations continue even after a person ceases to be an installer (Reg 24).
Enforcement
Ofgem may temporarily withhold payments on suspicion of non-compliance, with a 3-month investigation limit (Reg 19). On confirmed violation, it may withhold with 14-day notice (Reg 20), revoke vouchers (Reg 21), and require repayment with a minimum 28-day period, recoverable as civil debt (Reg 22). Installers have a right to request review of Ofgem decisions within 28 days, with an impartial reviewer appointed and decisions suspended pending the outcome (Reg 25).
Key numbers
| Metric | Value | Reference |
|---|---|---|
| Scheme period | 23 May 2022 to 31 March 2028 | Reg 1, Reg 15(4) |
| Heat pump capacity cap | 45 kWth (300 kWth shared ground loop) | Reg 9(1)(b) |
| Biomass capacity cap | 45 kWth | Reg 10(1)(b) |
| Minimum SCOP (heat pumps) | 2.8 | Reg 9(1)(d) |
| Commissioning window | 120 days before application | Reg 8(1)-(2) |
| ASHP/biomass voucher validity | 3 months | Reg 15(2) |
| GSHP voucher validity | 6 months or 31 March 2028 | Reg 15(2) |
| Last voucher date | 31 December 2027 | Reg 15(4) |
| Record retention | 6 years | Reg 17(1)(a) |
| Information notification | 14 days | Reg 17(1)(b)-(c) |
| Repayment period (minimum) | 28 days | Reg 22(3) |
| Review application deadline | 28 days | Reg 25(1) |
| Investigation limit (withholding) | 3 months | Reg 19(3) |
| Urban population threshold (biomass) | 10,000 | Reg 2, Reg 11(a) |
| Grant change notice period | 28 days | Reg 13(3) |
Defined terms
See source file defined terms register for the full list of 38 defined terms.
Cross-references
| Connected instrument | Nature of link |
|---|---|
| Energy Act 2008 s.100 | Legal basis for renewable heat incentive schemes |
| Gas Act 1986 s.5(1)(b) | "mains gas" definition |
| Energy Performance of Buildings (E&W) Regulations 2012 | EPC and recommendation report definitions |
| Housing and Regeneration Act 2008, s.68 | "social housing" definition |
| Microgeneration Certification Scheme (MCS) | Installer certification gateway |
| Clean Heat Market Mechanism | Related scheme (manufacturer obligation for heat pumps) |
| Schedule 1A grant categories | 4 sets allowing Secretary of State to differentiate by technology, property type, location |
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