Boiler Upgrade Scheme (BUS) Grant for Heat Pumps UK: Everything You Need to Know
The Boiler Upgrade Scheme (BUS) is the UK government's main financial incentive for replacing gas or oil boilers with low-carbon heating systems. Administered by Ofgem and funded by DESNZ (the Department for Energy Security and Net Zero), it offers a £7,500 grant toward the cost of an air source heat pump (ASHP), ground source heat pump (GSHP), or biomass boiler. The grant has been available since April 2022 and is currently funded to run to 2028. This guide explains who qualifies, what the grant covers, how the application process works, and what installation actually costs after the grant.
Grant Amounts (2024–2028)
| System | Grant Amount |
|---|---|
| Air Source Heat Pump (ASHP) | £7,500 |
| Ground Source Heat Pump (GSHP) | £7,500 |
| Water Source Heat Pump (WSHP) | £7,500 |
| Biomass Boiler | £7,500 |
The grant was uplifted in October 2023: ASHPs rose from £5,000 to £7,500, and biomass boilers rose from £5,000 to £7,500. GSHPs remained at £7,500 (previously £6,000). These are the current figures as of the 2024-28 funding round.
The grant is paid directly to your MCS-certified installer — it reduces their invoice to you. You never handle the money.
Who Is Eligible?
Properties That Qualify
- Located in England or Wales (Scotland has the Home Energy Scotland Heat Pump Grant; Northern Ireland is not covered by BUS).
- Must have an existing heating system that is being replaced — new-build properties are not eligible.
- Must have a valid Energy Performance Certificate (EPC) that does not contain an outstanding recommendation for loft insulation or cavity wall insulation (where applicable). If your EPC recommends these measures, you must have them installed first — or have a professional confirm that the property is unsuitable for them — before the BUS application will be accepted.
- Any property type is eligible: houses, bungalows, flats (though ASHPs are more complex in flats), and some commercial properties with domestic heating.
Buyers Who Cannot Use BUS
- Landlords receiving the grant for a property let to a tenant at the point of application (though there are exceptions for landlords meeting specific criteria — check with Ofgem).
- Properties that have already received a BUS grant for the same technology.
What the Installer Checks Before Applying
The BUS application is submitted by your MCS-certified installer, not by you. Before they apply, a competent installer will:
- Check the EPC: Confirm no outstanding loft or cavity wall insulation recommendations. If there are, they may advise you to get those done first (improving the EPC), or commission a written assessment confirming why the measures are not suitable (for example, the property has solid walls and no cavity to fill).
- Carry out a heat loss calculation (BS EN 12831): Size the heat pump to the property. An undersized or oversized pump will not perform efficiently. This calculation should cover room-by-room heat loss.
- Assess the existing heat emitters: ASHPs work best with large-surface radiators or underfloor heating. If your current radiators were sized for a high-temperature gas boiler (75 degrees C flow), they may need to be upgraded to work efficiently with an ASHP (typically 45-55 degrees C flow). The installer should identify which radiators need upgrading and quote accordingly.
- Confirm Ofgem's BUS portal is open for applications: The scheme has a fixed budget each financial year. Occasionally the annual budget is exhausted before year end, and applications pause. Your installer should confirm availability before you commit.
- Submit the BUS Voucher application on your behalf: The installer applies to Ofgem for a voucher before installation. The voucher is then redeemed at the point the installation is complete and signed off.
How to Apply
- Get a heat loss survey and quotes from at least two MCS-certified installers. This is not just good practice — Ofgem may ask for evidence that the system is correctly sized.
- Confirm your EPC is BUS-compliant (no outstanding cavity or loft insulation recommendations).
- Your chosen installer submits the BUS Voucher application via the Ofgem portal before installation begins.
- Once the voucher is issued (usually within a few days), installation can proceed.
- On completion, the installer redeems the voucher through Ofgem. You pay the balance — the total invoice minus £7,500.
Typical ASHP Installation Costs
Costs vary by property size, radiator compatibility, and whether any additional work (such as hot water cylinder replacement or radiator upgrades) is needed.
| Scenario | Before Grant | After £7,500 Grant |
|---|---|---|
| 3-bed semi, compatible radiators, standard ASHP | £10,000-£12,000 | £2,500-£4,500 |
| 3-bed semi, radiator upgrades needed | £13,000-£16,000 | £5,500-£8,500 |
| 4-bed detached, UFH throughout, large ASHP | £14,000-£20,000 | £6,500-£12,500 |
| Ground source heat pump, 4-bed detached | £20,000-£35,000 | £12,500-£27,500 |
These are market-average figures as of 2024-25. Get at least two quotes — ASHP pricing varies significantly between installers.
Running Cost Comparison: Gas Boiler vs. ASHP
The key question for most homeowners is not the capital cost but the ongoing running costs. ASHPs are powered by electricity, which is currently more expensive per kWh than gas. However, a well-specified ASHP runs at a Coefficient of Performance (COP) of 2.5-4.0, meaning it generates 2.5-4 units of heat for every 1 unit of electricity consumed.
| Metric | Gas Boiler | ASHP |
|---|---|---|
| Energy cost per kWh (approx. 2024-25) | ~7p/kWh (gas) | ~24p/kWh (electricity) |
| Typical seasonal efficiency | 85-92% (SEDBUK) | 250-350% (COP) |
| Annual heating cost, 3-bed semi (15,000 kWh heat needed) | ~£1,300-£1,500 | ~£1,000-£1,440 |
| Carbon emissions (kg CO2/kWh delivered heat) | ~0.22 | ~0.05-0.08 (grid mix) |
For homes replacing oil boilers, the running cost case for ASHPs is much stronger — oil currently costs around 7-9p/kWh but often runs at 85% efficiency, giving a delivered cost of ~8-11p/kWh. An ASHP on electricity at 24p/kWh with a COP of 3.0 delivers heat at ~8p/kWh — broadly comparable.
Do You Need Planning Permission for an ASHP?
In most cases, no. ASHPs benefit from Permitted Development (PD) rights under Class G, Part 14, Schedule 2 of the GPDO 2015 in England. To benefit, the installation must meet these conditions:
- Only one ASHP per property.
- The unit must not be installed on a wall or roof that faces a highway and is visible from that highway.
- In a conservation area or World Heritage Site, the unit must not be installed on a wall facing a highway or visible from a public road.
- The unit must be at least 1 metre from the property boundary (updated in 2021 guidance).
- On a flat roof, the unit must not be within 1 metre of the roof edge.
- Flats do not benefit from PD rights for ASHPs — planning permission is required.
- Listed buildings require Listed Building Consent in addition to any planning permission.
If your installation falls outside PD rights, a householder planning application costs £258 in England.
Domestic RHI vs. BUS: What's the Difference?
The Domestic Renewable Heat Incentive (RHI) was the predecessor scheme — it paid quarterly payments for seven years based on the heat your system generated. The domestic RHI closed to new applications in March 2022. If you are already receiving domestic RHI payments (i.e., you installed an eligible system before March 2022), you will continue to receive those payments until your seven-year term ends. You cannot receive both domestic RHI and BUS.
BUS is a one-off capital grant, not an income stream. It is simpler to access and does not require metering or ongoing reporting.
MCS Certification: What It Means and How to Verify
MCS (Microgeneration Certification Scheme) certification is mandatory for BUS. It is a quality assurance standard covering both the products (the heat pump itself must be MCS-approved) and the installer.
To verify an installer's MCS certification:
- Visit mcscertified.com/find-an-installer.
- Search by postcode and technology (heat pumps).
- Check the installer's certificate is current — MCS accreditation is renewed annually.
An uncertified installer cannot apply for BUS vouchers, and you will not receive the grant. Do not instruct an installer who cannot demonstrate current MCS certification.
Is the BUS Worth It?
For the right property — one that is reasonably well insulated, has or can have large radiators or UFH, and is in England or Wales — the BUS makes an ASHP installation significantly more accessible. The £7,500 grant covers 40-70% of a typical installation cost and brings many properties into a range where the investment is recoverable over 8-12 years in running cost savings alone.
For poorly insulated properties, the economics are less favourable. A heat pump in a draughty Victorian terrace will underperform — prioritise insulation first, then revisit the BUS.
Want to know how an ASHP affects your EPC rating? Our EPC guide for buyers and sellers covers the scoring system in detail. For a deeper dive into ASHP vs GSHP installation specifics and the fabric-first preparation steps, see our heat pump installation guide. For a homeowner-focused walkthrough covering the suitability checklist, COP expectations, running cost comparison, and BUS grant application process, see our heat pump installation guide for homeowners.