The Department for Energy Security and Net Zero has issued a corrected Statutory Instrument for the Boiler Upgrade Scheme (BUS). S.I. 2026/390 was laid on 1 April 2026 as a substitute for S.I. 2026/368 and comes into force on 28 April 2026. The change regularises minor errors in the earlier instrument and confirms a package of policy updates to widen eligibility and streamline administration in England and Wales. (statutoryinstruments.parliament.uk)
Air‑to‑air heat pumps (A2A) are brought into scope for the first time. The Government confirms a £2,500 grant for A2A installations in domestic properties, adding a lower‑cost pathway for homes with ‘dry’ heating systems. Non‑domestic buildings remain out of scope for A2A under the scheme. (assets.publishing.service.gov.uk)
Hydronic heat pumps (air‑to‑water and ground source) remain core to BUS support but the rules are updated to reflect mixed‑technology systems. Installations can be paired with supplementary electric appliances that do not burn fossil fuel, provided the BUS‑funded heat pump can meet the property’s full space‑heating demand. Biomass back‑up alongside a BUS‑funded heat pump is not supported. (assets.publishing.service.gov.uk)
Capacity thresholds are clarified. Individual plants are capped at 45 kWth, with a combined cap of 70 kWth where multiple heat pumps serve one property; shared ground loop systems retain a 300 kWth limit. These thresholds are designed to preserve the scheme’s focus on homes and small non‑domestic premises while allowing multi‑unit solutions where appropriate. (assets.publishing.service.gov.uk)
Performance requirements are retained. Hydronic heat pumps supported by BUS must continue to meet a minimum seasonal efficiency standard equivalent to a SCOP of at least 2.8 under MCS rules, with compliance assessed against Secretary of State‑approved standards at commissioning. (ofgem.gov.uk)
The requirement for a valid Energy Performance Certificate (EPC) as a condition of eligibility is removed from 2026/27, to widen access where certificates have lapsed or are not readily available. Applicants should still expect Ofgem to verify core property information as part of routine checks. (assets.publishing.service.gov.uk)
Certification is standardised on the Microgeneration Certification Scheme (MCS). “Installer” now means an MCS‑certified person (or a subsequent MCS version approved by the Secretary of State), and references to equivalent schemes are removed. DESNZ will continue to publish and update the list of approved standards and grant categories. (assets.publishing.service.gov.uk)
Consumer protection at the point of sale is strengthened. Installers must deduct the BUS voucher value from the customer quote so the grant is applied upfront, reducing exposure if a firm later fails. This formalises current best practice and simplifies payments for property owners. (assets.publishing.service.gov.uk)
Definitions are updated to ensure consistent application. “Urban area” now references the Office for National Statistics 2021 Rural‑Urban Classification released on 22 August 2025, aligning BUS rules with the latest national geography. (ons.gov.uk)
Funding and timelines are confirmed for the remainder of the decade. Government has signalled BUS will operate through 2029/30 with rising annual budgets, providing policy certainty for households, installers and supply chains. S.I. 2026/390 gives effect to the next phase from 28 April 2026. (assets.publishing.service.gov.uk)
What this means in practice is straightforward. Homeowners gain a new route to decarbonise with A2A support and clearer pricing as grants are deducted from invoices. Installers should align designs to the 45 kWth/70 kWth/300 kWth capacity limits, maintain MCS compliance, and ensure hydronic systems meet full space‑heating demand. Public‑sector estate managers and SMEs should note that A2A support is limited to domestic buildings; hydronic options remain available where scheme conditions are met. (assets.publishing.service.gov.uk)