The £7,500 Boiler Upgrade Scheme: Complete 2026 Guide

The Boiler Upgrade Scheme provides upfront capital grants in England and Wales toward installing a low-carbon heating system. The headline numbers in May 2026:

• £7,500 grant for an air source heat pump
• £7,500 grant for a ground source heat pump (including water source variants)
• £5,000 grant for biomass (very limited — rural off-gas-grid only)
• Funding confirmed through 31 March 2028
• Annual budget of £295m for 2025-26, rising to £320m in 2026-27

The grant is administered by Ofgem, paid directly to your MCS-certified installer, and deducted from your invoice. You never see the cash; you simply pay the post-grant balance. Combined with 0% VAT on heat pump installations until 31 March 2027, a typical Cornwall ASHP install that quoted at £18,000 list price comes out at £10,500 inc. VAT after grant.

The scheme has been an unqualified delivery success: 2025-26 fiscal year saw 47,000 grants issued (up from 12,500 in 2022-23), and Cornwall ranks in the top 10 local authorities for grant uptake per capita, partly because of the off-gas-grid rural housing stock. Across the South West region, MCS heat pump installations passed 80,000 cumulative in Q1 2026.

Visit our grants page for current funding status or call 01209 596 002 to start an application.

The grant value depends on technology, not property size or income.

Air source heat pump: £7,500

Applies to monobloc and split ASHP systems sized appropriately to the property heat loss. Hybrid heat pumps (ASHP + boiler) are excluded unless the heat pump can independently meet 100% of design heat load — in which case they are treated as ASHP for the grant. The vast majority of grants are for ASHP installations.

Ground source heat pump: £7,500

Applies to closed-loop and open-loop ground source systems, water source heat pumps drawing from rivers, lakes or boreholes, and shared ground arrays serving multiple properties. The grant amount is the same as ASHP despite the higher capital cost — which is why GSHPs are growing more slowly in proportion to ASHPs nationally.

Biomass: £5,000

Available only for rural off-gas-grid properties (defined by RPC2.1 rural classification) and only for high-efficiency wood pellet boilers. Wood-burning stoves and log boilers do not qualify. CCS does not currently install biomass — the operating economics rarely beat ASHP and pellet supply chains in Cornwall are limited.

What was the historical journey?

Initial 2022 launch: £5,000 ASHP, £6,000 GSHP, £5,000 biomass. October 2023 uplift: £7,500 / £7,500 / £5,000. The scrapping of the loft and cavity insulation prerequisite in May 2024 effectively widened eligibility further by removing a major barrier for older Cornish stone-built properties where retrospective wall insulation is impractical. See our BUS glossary entry.

Eligibility is broad and most Cornwall homeowners qualify. The criteria as of May 2026:

Property type

• Owner-occupied homes in England and Wales (Scotland has separate Home Energy Scotland scheme; Northern Ireland a separate scheme)
• Privately rented homes (the landlord applies, though the tenant may also benefit indirectly via lower bills)
• Small non-domestic premises with peak heat demand under 45kWth (small offices, GP surgeries, village halls, churches, small hotels)
• Self-build properties via a specific exemption (must have been substantially built by the same person who lives there)

EPC requirements

You must hold a valid Energy Performance Certificate (EPC) — not expired, not over 10 years old — but there is no minimum EPC band. The previous requirement for no outstanding loft or cavity insulation recommendations was scrapped in May 2024.

If your EPC is missing, expired or has issues, CCS can refer you to an accredited Domestic Energy Assessor in Cornwall — typical EPC cost is £60-100 and takes 2-3 weeks.

Property what you replace

The new grant rules allow replacement of any existing heating system — gas, oil, LPG, electric, solid fuel, or no heating at all. Originally the scheme excluded mains gas replacements, but that restriction was dropped in 2023. Today, even a homeowner with a working modern gas combi can claim BUS to switch to a heat pump.

Installer requirements

The installer must be MCS certified for the technology being installed. CCS holds MCS certification for ASHP and GSHP — our MCS installer number is on every quote. Without an MCS installer, the grant cannot be claimed. Always verify your installer's MCS status at mcscertified.com before signing.

The exclusion list is short:

New-build properties

Properties that have never been occupied are excluded — the rationale being that new-builds should comply with the Future Homes Standard and have heat pumps included from day one. The self-build exemption covers properties where the homeowner has substantially built the property themselves, even if it is technically a new dwelling.

Social housing

Council and housing association properties are excluded from BUS — they are funded separately via the Social Housing Decarbonisation Fund (SHDF) administered by DESNZ. Cornwall Council and Coastline Housing have active SHDF programmes for their tenants.

Replacing biomass

You cannot use BUS to replace an existing biomass system with a heat pump — Ofgem's reasoning is that biomass is already considered low-carbon. (You can replace a biomass with another biomass, claiming the £5,000 grant.)

Hybrid heat pumps (mostly excluded)

Systems where a heat pump operates alongside a boiler and the heat pump cannot meet 100% of design heat load do not qualify. This was tightened in 2024 to prevent gaming. If you need a hybrid, the grant is forfeit — though the lower capex of a hybrid can still make economic sense in some legacy properties.

Properties with existing low-carbon heat

If your property already has a working heat pump, district heating connection or biomass, you cannot claim BUS to replace it with another low-carbon system. The scheme is intended to drive new conversion from fossil fuels.

Park homes / mobile homes

Park homes are excluded as they fall outside Building Regulations Part L for heating systems. Some park home schemes have been funded via Warm Homes Local Grant instead — see our grants page.

From first enquiry to grant-discounted invoice, the typical Cornwall BUS journey takes 8-12 weeks. Here is the day-by-day breakdown:

Week 1: Initial survey

• Day 1: You call CCS on 01209 596 002 or fill our enquiry form
• Day 3-7: We visit your property for a free heat loss survey, taking room-by-room measurements, fabric analysis, photographing existing system, and discussing emitter options

Week 2: Detailed quote

• Day 8-12: We produce a full MCS-compliant quote including heat pump model, hot water cylinder, controls, pipework, electrical works, radiator upgrades, and a comprehensive heat loss report
• Day 12-14: You review and ask any questions — we often do a second site visit if helpful

Week 3-4: Sign-off and BUS application

• Day 15: You sign the contract and a single Ofgem consent form
• Day 15-17: CCS submits your BUS application via the Ofgem MCS portal — including your address, EPC details, the quoted heat pump model, and your consent
• Day 17-35: Ofgem processes the application. Approvals are typically 2-3 weeks at current volumes; we will chase if it overruns 4 weeks

Week 5-7: Equipment ordering and scheduling

• Once Ofgem voucher is confirmed, we order your heat pump and cylinder
• Lead times for our preferred Vaillant aroTHERM plus and Daikin Altherma 3 R range are 2-3 weeks in May 2026
• We provisionally schedule install dates, confirmed once equipment is in our warehouse

Week 8-9: Installation

• Typical 3-5 day install on site
• Day 1: Old system decommissioning, base laid, electrical first fix
• Day 2-3: Heat pump landed and plumbed, cylinder installed, controls wired
• Day 4: Commissioning, customer handover, system explanation
• Day 5: Snagging, electrical sign-off, MCS commissioning certificate uploaded

Week 9-10: Grant deducted and final invoice

• The £7,500 grant is paid by Ofgem directly to CCS within 5 working days of the MCS certificate being uploaded
• Your final invoice is the contract value minus the £7,500 — you only ever pay the net amount

The whole process is genuinely paperwork-light from your perspective: one consent form, one contract signature, and you are done.

CCS Heating & Renewables manages every aspect of the BUS process so you do not have to interact with Ofgem directly. Here is exactly what we handle:

• Heat loss calculation — full MCS-compliant room-by-room heat loss using EN 12831 methodology
• Heat pump sizing and selection — matched to your heat loss, fabric and emitter strategy
• EPC verification — we check your existing EPC validity; if missing or expired, we refer you to a Cornwall-based DEA
• BUS voucher application — submitted via the Ofgem MCS Installer Database within 48 hours of contract sign-off
• Ofgem chase — we monitor application status weekly and chase if anything stalls
• Equipment ordering and scheduling — only after voucher is confirmed, eliminating any risk of you paying for kit before grant approval
• Installation and commissioning — by our own MCS-certified engineers (we do not subcontract)
• MCS certificate — uploaded to the central database within 10 working days of commissioning
• Grant redemption — Ofgem pays us directly, your invoice shows £7,500 deducted
• Documentation pack — you receive a folder containing the MCS certificate, heat loss report, commissioning data, weather compensation curve setup, warranty registrations, IBG certificate, electrical certificate (BRCC), and operating manual

Total time you spend on paperwork: about 30 minutes total across the whole project. Total time CCS spends on Ofgem admin: typically 4-6 hours per project, included in our quote.

Call 01209 596 002 to start your BUS application or visit our grants page.

BUS can be combined with several other funding streams, but rules around stacking are nuanced.

BUS + 0% VAT (until March 2027)

The 0% VAT on heat pump installations applies automatically and stacks with BUS. The grant is calculated on the inc-VAT contract value, and the result is a deeper effective discount. Worth claiming before VAT returns to 5% (or potentially higher) in April 2027.

BUS + ECO4 (limited)

If you qualify for ECO4 you generally get a fully funded ASHP via the ECO4 lead generator route, so BUS is not needed. The two cannot be claimed for the same measure on the same property.

BUS + Warm Homes Local Grant

WHLG covers a range of measures (insulation, solar, heat pump). For the heat pump specifically, WHLG and BUS cannot stack — but WHLG can fund insulation and solar while BUS funds the heat pump on the same property. CCS can coordinate a combined application via Cornwall Council's Community Energy Plus partner.

BUS + Public Sector Decarbonisation Scheme

PSDS covers public sector buildings only. BUS is residential-and-small-commercial only. They do not overlap.

BUS + 0% APR finance

The grant is deducted before the finance amount is calculated. CCS partners with Phoenix Financial Services to offer 0% APR over 24 months on the post-grant balance, subject to status. See our finance page.

BUS + SEG (Smart Export Guarantee)

If you also install solar PV, SEG is a separate income stream administered by your electricity supplier and unaffected by BUS. Combining solar PV + battery + heat pump is the gold-standard 2026 retrofit and we install dozens of these combined packages annually across Cornwall.

BUS is funded to 31 March 2028. What happens next is still being shaped, but the direction of travel is clear.

Likely successor: Clean Heat Market Mechanism (CHMM)

The Clean Heat Market Mechanism is the policy framework intended to take over from BUS post-2028. It works on the supply side: gas boiler manufacturers must sell a rising proportion of heat pumps as a fraction of total appliance sales, on penalty of fines per unit short. CHMM was deferred from 2024-25 to 2026-27 after lobbying, and the 2025 review pushed full implementation to 2028. The expectation is that CHMM, combined with falling heat pump prices and possibly a smaller transitional consumer grant (£3,000-5,000), will replace BUS.

Risk of grant cliff

If CHMM is delayed again and BUS expires without successor, there could be a 6-12 month gap with no consumer grant — followed by panic policy-making. Our advice to Cornwall homeowners: if you are seriously considering a heat pump in 2026-2027, claim BUS while it is in place. Waiting for whatever comes next risks losing the £7,500.

Future fuel costs

Even if grants reduce, the underlying economics of heat pumps will continue to improve. Wholesale electricity prices are projected to fall 15-25% in real terms through 2030 as offshore wind and grid storage scale, while gas remains exposed to international LNG markets and the UK ETS carbon price. The ratio of electricity:gas unit prices, currently around 4.3:1, is widely forecast to fall to 3.0:1 or lower by 2030.

Building Regulations

The Future Homes Standard already mandates heat pumps in new builds from 2025-2026. The next step — likely 2028-2030 — is a phased ban on new gas boiler installations in existing properties when the existing system fails. This is contested politically but the policy machinery is being built.

The takeaway: heat pumps are the medium-term direction whatever the precise grant trajectory. Locking in £7,500 in 2026 is the cleanest deal available. Visit our heat pump page or call 01209 596 002.