The Boiler Upgrade Scheme rulebook has been refreshed. Statutory Instrument 2026/390 was laid on 1 April and takes effect on 28 April 2026, replacing a previous version and locking in new definitions, grant categories and installer obligations for England and Wales. For HVAC SMEs, this is a clear signal to update quoting, cashflow and compliance processes ahead of the new start date. (statutoryinstruments.parliament.uk)

The headline shift is technology scope. Air‑to‑air heat pumps join the scheme for domestic properties with a flat £2,500 grant, while existing levels stay at £7,500 for air‑to‑water and ground‑source units and £5,000 for biomass. DESNZ framed air‑to‑air as a way to heat in winter and cool in summer; Ofgem’s draft guidance confirms the amounts that apply from applications properly made on or after 28 April. (gov.uk)

Installer rules are tighter and simpler. Ofgem’s draft guidance states that consumer-facing BUS work must be carried out by MCS‑certified firms that also belong to a Secretary of State‑approved consumer code. Crucially, the full grant value must be deducted upfront from quotes and invoices-installers must not request or accept payment of the discounted amount. Voucher redemption still occurs after commissioning, with three months for air‑to‑air/air‑to‑water/biomass and six months for ground‑source. Plan deposit terms and working capital accordingly. (ofgem.gov.uk)

Paperwork friction is eased. Retrofit properties no longer need a valid EPC to apply. Where an EPC exists it should be referenced; where it does not, Ofgem will accept alternative evidence (such as utility bills) and, where available, details from an expired EPC. Expect fewer aborted quotes due to document gaps, but keep evidence packs tight. (ofgem.gov.uk)

System design rules are clarified without becoming over‑prescriptive. Hydronic heat pumps must still meet the full space‑heating and hot‑water demand, alone or alongside non‑biomass supplementary electric appliances. Capacity caps apply: 45 kWth per individual plant, up to 70 kWth combined on multi‑unit installs, and 300 kWth for shared ground loops. The minimum seasonal performance for hydronic units remains 2.8 (SCOP), assessed against the Secretary of State‑approved standard at commissioning. Quote and size with these thresholds in mind. (assets.publishing.service.gov.uk)

Eligibility boundaries matter for pipeline planning. Air‑to‑air heat pumps are residential‑only under BUS; non‑residential buildings remain out of scope for this technology, so commercial quotes should continue to focus on hydronic solutions or biomass where permitted. (ofgem.gov.uk)

The scheme horizon has been extended. Government’s consultation response confirms BUS will run through 2029/30 with rising annual budgets-useful certainty for forward orders and hiring. That continuity underpins finance decisions on vans, tools and training for smaller contractors. (assets.publishing.service.gov.uk)

Demand signals are firmer but realistic. Under the Warm Homes Plan, the government now aims for more than 450,000 annual heat pump installations by 2030-a recalibrated target that still implies steady growth from today’s levels. BUS is positioned as one of the levers to get there, alongside other retrofit programmes and low‑interest loans. (gov.uk)

Where air‑to‑air fits commercially: it opens a simpler install path for flats and smaller homes without wet systems, at lower ticket sizes. DESNZ cites a typical installed cost around £4,500 in a flat or small house; a £2,500 grant can wipe out most of that headline price, widening your addressable market if you hold the right certifications. (gov.uk)

Cashflow will sit front and centre this spring. With the grant deducted upfront and payment released only on voucher redemption, SMEs will carry more working capital per job. Build this into quotes, milestones and supplier terms; reconfirm commissioning dates, and keep MCS paperwork watertight to avoid delays to redemption. Ofgem’s guidance is explicit on itemised quotes and evidence, so align CRM templates now. (ofgem.gov.uk)

Operationally, three near‑term actions stand out. First, validate MCS scope and consumer‑code membership cover for air‑to‑air as well as hydronic work. Second, retrain sales teams on the new EPC approach and evidence substitutes to reduce drop‑offs. Third, check designs meet BUS capacity caps and performance standards, especially where multi‑unit packages or shared ground loops are planned. These are low‑cost changes that protect margin and speed conversion once the rules go live on 28 April. (ofgem.gov.uk)