Boiler Upgrade Scheme Cornwall 2026 — Claim Your £7,500 Grant

The Boiler Upgrade Scheme (BUS) is a government grant administered by Ofgem on behalf of the Department for Energy Security and Net Zero (DESNZ). It pays homeowners and small non-domestic property owners in England and Wales a fixed grant towards replacing an oil, LPG, gas or direct-electric heating system with a low-carbon alternative.

Current grant values (May 2026):

• £7,500 for an air source heat pump (ASHP) — the most common in Cornwall.
• £7,500 for a high-temperature heat pump (still subject to MCS HP product list eligibility).
• £5,000 for a ground source heat pump (GSHP) or water source heat pump.
• £5,000 for a biomass boiler in rural off-gas-grid properties (very limited eligibility — see below).

The scheme was extended in October 2023 from a £5,000/£6,000 grant to the current £7,500/£5,000 levels, and again in 2024 to remove the EPC requirement and the building-loft-insulation prerequisite. The scheme is now open to 31 March 2028 and is uncapped in budget (each year Ofgem releases ~£150m of vouchers on a first-come-first-served basis until exhausted, then refreshes the following April).

Following the May 2024 reform, the eligibility test for the Boiler Upgrade Scheme in Cornwall is straightforward. You qualify if all of the following are true:

• You own the property (owner-occupier or private landlord). Tenants cannot apply directly but landlords can.
• The property is in England or Wales (Cornwall qualifies).
• The property is a domestic dwelling or a small non-domestic building (capacity rating <45 kW).
• The system you're replacing is fossil fuel (oil, LPG, mains gas) or direct-electric (storage heaters, panel heaters).
• The installer is MCS-certified and listed on the Ofgem BUS installer database (CCS is).
• The new heat pump or biomass system is on the MCS product certification list and sized to the property's heat loss.

What is no longer required (since the May 2024 reform):

• ❌ No minimum EPC rating
• ❌ No loft / cavity insulation prerequisite
• ❌ No recommendation for loft or cavity insulation on the EPC
• ❌ No mortgage lender consent
• ❌ No income test (this was never required — but commonly believed otherwise)

Listed buildings are eligible. New-build properties are not (newbuild has separate Building Regs Part L pathways — see our self-build renewables page).

The grant amount depends on the technology, not the property:

• £7,500 — Air source heat pump (ASHP). The standard Cornwall pathway. Covers all MCS-listed ASHPs from Daikin, Vaillant, Mitsubishi, Samsung, Grant, Worcester Bosch and others. Typical fitted cost in Cornwall £11,500–£16,800 before grant — net of grant £4,000–£9,300.
• £7,500 — High-temperature ASHP. Same grant value. Suits older Cornish granite or cob properties where keeping existing radiators at 70°C flow is preferred over a microbore upgrade.
• £5,000 — Ground source heat pump (GSHP). Higher installation cost (typical £18,000–£32,000) due to borehole or slinky-loop ground array. Best suited to large rural Cornwall properties with paddock space.
• £5,000 — Biomass boiler. Only available in rural off-gas-grid areas, and the property must be RHI-style eligible. Rarely cost-effective in Cornwall — heat pumps almost always win.

For a property-by-property comparison see the table further down this page.

Step-by-step, here is what happens when you instruct CCS for a Boiler Upgrade Scheme Cornwall installation. All the paperwork is ours — your involvement is signing two consent forms.

1. Free Cornwall heat-loss survey — our engineer visits your home (typically within 7–10 days of enquiry) and conducts a BS EN 12831 heat-loss calculation, photographs your existing system, measures radiators and pipework, and discusses cylinder placement.
2. System design and quote — we send a written quote with bill of materials, radiator schedule, BUS grant applied, 0% VAT applied, and our 12-month workmanship guarantee.
3. BUS voucher application to Ofgem — we apply for your voucher via the MCS Certification Body portal. You sign two consent forms electronically. Voucher issue: typically 4–6 weeks.
4. Voucher received — installation booked — once Ofgem issues the voucher (valid for 3 months from issue, 6 months for GSHP), we book installation dates with you.
5. Installation — 3–5 days on site for an air source heat pump retrofit, longer for ground source. Existing boiler removed, new system commissioned to MCS MIS 3005 standards.
6. Voucher redemption — we submit installation evidence (photos, commissioning data, MCS certificate) to Ofgem within 28 days of completion. Grant is paid directly to CCS within 14 days. You never see the £7,500 — it has already been deducted from your invoice.
7. Post-install audit cooperation — Ofgem audits ~10% of installations within 18 months. We handle audit response on your behalf if your property is selected. The audit is a brief on-site visit to verify the heat pump is installed and operating as specified.

Cornwall has the highest off-gas-grid penetration in England — 47% of homes burn oil, LPG or use direct electric. That makes the running-cost saving from a heat pump particularly large here. Worked example for a typical 3-bed Cornish semi using 16,000 kWh of heat per year:

• Oil boiler (kerosene at 78p/litre): 16,000 kWh ÷ 10.3 kWh per litre ÷ 0.88 efficiency = 1,765 litres/year = £1,377/year.
• LPG boiler (90p/litre): 16,000 ÷ 6.6 ÷ 0.88 = 2,754 litres = £2,479/year.
• Air source heat pump on Octopus Cosy 12p off-peak: 16,000 ÷ 4.0 SCOP = 4,000 kWh, weighted average tariff 17p = £680/year.
• Air source heat pump on standard 24.67p tariff: 4,000 kWh × 24.67p = £987/year.

So replacing an oil boiler with an ASHP on a sensible tariff typically saves £697/year; replacing an LPG boiler saves £1,799/year. Pair with solar PV and the saving climbs further. For the calculation methodology see our payback calculator.

For 95% of Cornwall homes, the answer is air source (ASHP). It costs less upfront, qualifies for the higher £7,500 grant, and Cornwall's mild Atlantic climate (average winter low ~3°C, never below -6°C in the last 30 years) is ideal for ASHP performance. Modern ASHPs operate efficiently down to -25°C, so Cornwall is, in heat-pump terms, the easiest county in the UK.

Ground source heat pumps (GSHP) make sense in a narrow set of Cornish scenarios:

• Large rural property with >0.5 acres of accessible paddock for slinky-loop ground array, OR
• Limited outdoor wall space for an ASHP unit, AND
• High annual heat demand (>25,000 kWh/year).

GSHP installation cost is typically £18,000–£32,000 versus £11,500–£16,800 for ASHP, but GSHP SCOP is higher (typically 4.5–5.2 vs 3.8–4.5 for ASHP), so running costs are 10–15% lower. The £2,500 lower BUS grant for GSHP (£5,000 vs £7,500) usually offsets the running-cost advantage over a 15-year horizon. For most Cornish customers we recommend ASHP.

For more on our heat pump installations see our heat pump installation hub, and the Redruth, Truro and St Austell service pages.

Typical fully installed pricing for Cornwall air source heat pump systems, after the £7,500 BUS grant and 0% VAT (figures correct May 2026):

All pricing includes the heat pump, hot water cylinder (180–300L), heat-loss survey, design, BUS application, installation, commissioning, MCS certification, and Building Regulations Part L notification. Financing is available 0% APR over 24 months or low-rate spread over 60–120 months — see finance options.

The £7,500 Boiler Upgrade Scheme can be combined with other Cornwall grants to bring total funding above £15,000 in some cases. Three stacks to consider:

• BUS + Warm Homes: Local Grant (Cornwall Council) — Cornwall Council administers WH:LG for households with income under £36k in EPC D, E, F or G properties. Provides up to £30,000 towards heating, insulation and solar. Cannot fund the same kWh of work twice, but can fund insulation, ventilation and rewiring alongside the BUS-funded heat pump. See our grants overview.
• BUS + ECO4 — eligible (low-income or benefit-receiving) Cornwall households can stack ECO4 funding for insulation alongside a BUS-funded heat pump. ECO4 doesn't fund heat pumps directly but enables the insulation upgrade that lets the heat pump run at lower flow temperature. See our ECO4 Cornwall page.
• BUS + 0% VAT — automatic on all heat pump installations to March 2027. Saves ~20% on the post-grant balance.

Free solar via ECO4 is also available — see free solar panels Cornwall.

We see a steady stream of Cornish homeowners who applied through a non-specialist installer, were rejected by Ofgem, and came to us to redo the application. The four most common reasons for rejection:

• Heat-loss calculation not BS EN 12831 compliant — Ofgem audits the heat-loss methodology. We use validated software (Heat Engineer or HARP) for every Cornwall survey.
• Property not occupied as residential dwelling — empty holiday lets and second homes with no occupier on record can be rejected. We confirm occupancy status before applying.
• System sized incorrectly — undersized systems fail the MCS PAS 2035 test. We never undersize a heat pump to "fit a budget".
• Installer not on Ofgem BUS register — surprising number of "MCS-certified" installers are not actually BUS-authorised. We are. You can verify CCS on the MCS Certified register and Ofgem's BUS installer search.

Doing it right the first time matters because Ofgem will not re-issue a voucher to the same property within 12 months of a rejection in most cases.