BUS Grant Application Guide: MCS Installer Requirement, Eligible Properties and £7,500 Process
Quick Answer: The Boiler Upgrade Scheme (BUS) is an Ofgem-administered grant in England and Wales giving £7,500 towards an air-source or ground-source heat pump and £5,000 towards a biomass boiler (rural, off-gas only). The grant is claimed by an MCS-certified installer on the homeowner's behalf — homeowners cannot apply directly. The property needs a valid EPC, the system must be MCS-certified up to 45 kW, and it must replace a fossil-fuel system. The scheme is funded to 2028.
Summary
The Boiler Upgrade Scheme is the main capital subsidy for low-carbon heating in England and Wales. It exists to close the gap between the cost of a gas boiler and the cost of a heat pump, and since the October 2023 uplift the headline figure has been £7,500 — a number that genuinely changes the conversation with a homeowner because it now covers a large slice of a typical air-source heat pump install.
The structure trips up tradespeople new to it: the homeowner never applies. The MCS-certified installer registers the job, generates a voucher quotation, installs the system, and then redeems the voucher — the grant is deducted from the customer's invoice, so the customer pays the balance. This means being (or partnering with) an MCS-certified installer is the entry ticket; without MCS certification you cannot offer BUS at all.
The other thing to understand is what makes a property eligible. The home must be in England or Wales, have a valid Energy Performance Certificate, and be replacing a fossil-fuel heating system (gas, oil, LPG or electric). New-build is generally excluded, with a self-build exception. The eligibility detail that has shifted over the life of the scheme is the rule about insulation recommendations on the EPC, so always check the current Ofgem guidance before quoting.
Key Facts
- Scheme name — Boiler Upgrade Scheme (BUS), England and Wales, administered by Ofgem.
- Grant values — £7,500 air-source heat pump (ASHP); £7,500 ground-source heat pump (GSHP, including water-source); £5,000 biomass boiler.
- Uplift date — ASHP/GSHP grants rose to £7,500 (from £5,000/£6,000) in October 2023.
- Installer applies — only an MCS-certified installer can apply for and redeem the grant; homeowners cannot apply directly.
- Capacity cap — eligible systems up to 45 kW thermal output.
- EPC required — property must have a valid EPC (less than 10 years old).
- Replaces fossil fuel — must replace a fossil-fuel system (mains gas, oil, LPG, or electric); cannot be installed alongside an existing fossil-fuel heating system serving the same space (no "hybrid topping-up" of a retained gas boiler under BUS).
- Biomass conditions — biomass grant only for rural, off-gas-grid properties meeting emissions limits.
- New build excluded — except eligible self-build properties.
- One grant per property — a property that has already received BUS (or earlier RHI) funding for the same measure is not eligible again.
- Voucher validity — vouchers have a redemption window (typically 3 months for ASHP/biomass, 6 months for GSHP) from issue.
- Funding to 2028 — the scheme budget was increased and extended to 2028.
- MCS + consumer code — the installer must be MCS certified and a member of a consumer-protection code (e.g. RECC or HIES).
Quick Reference Table
Quoting a heating job? squote turns a 2-minute voice recording into a professional quote.
Try squote free →| Measure | BUS grant | Typical eligibility notes |
|---|---|---|
| Air-source heat pump (ASHP) | £7,500 | On or off gas grid; ≤45 kW; MCS certified |
| Ground/water-source heat pump (GSHP) | £7,500 | ≤45 kW; MCS certified; longer voucher window |
| Biomass boiler | £5,000 | Rural, off-gas-grid only; emissions limits |
| Shared ground loop (per dwelling) | £7,500 per dwelling | MCS certified district/communal arrangements |
| New-build dwelling | Not eligible | Self-build exception applies |
Detailed Guidance
Who can offer BUS: the MCS requirement
BUS is built on MCS (Microgeneration Certification Scheme). To deliver it you must be an MCS-certified installer (or work under one) with the relevant technology scope, and a member of an MCS-approved consumer code such as RECC or HIES. Becoming MCS certified involves applying through a certification body, having your competence and processes assessed, and submitting an example installation. If you are a heating engineer wanting to move into heat pumps, this certification — not the grant paperwork — is the real barrier to entry, so plan the lead time.
The application flow (installer-led)
BUS process (installer's view)
------------------------------
1. Confirm property eligibility
- England/Wales, valid EPC, replacing fossil fuel,
not new build (unless self-build).
2. Design the system to MCS standards
- Room-by-room heat loss (MCS 003 / MIS 3005),
emitter sizing, hot-water cylinder, controls.
3. Register the job on the Ofgem BUS portal & request a voucher
- Installer submits property + measure details.
- Homeowner consent recorded; Ofgem issues a voucher.
4. Install the system
- Commission to MCS standards, generate MCS certificate.
5. Redeem the voucher within the validity window
- Installer submits commissioning + MCS cert; grant is
paid to the installer.
6. Discount the customer's invoice by the grant value
- Customer pays the net (price minus £7,500).
The customer experiences this as a discount, not a rebate they chase — that simplicity is a selling point.
Property eligibility in detail
- Location — England or Wales (Scotland uses Home Energy Scotland grants/loans instead; Northern Ireland is separate).
- EPC — a valid EPC (under 10 years old) is required. Historically the EPC had to have no outstanding recommendations for loft or cavity-wall insulation, but this requirement has been the subject of change during the scheme — always check the live Ofgem rule before quoting, because telling a customer they must insulate first when they don't (or vice-versa) loses the job or breaks compliance.
- Existing system — must replace fossil-fuel heating. You cannot use BUS to add a heat pump to a home that keeps a working gas boiler for the same heating duty.
- Self-build — privately built/commissioned new homes can qualify; standard developer new-build cannot.
- Capacity — system ≤ 45 kW. Larger commercial/multi-dwelling schemes have specific rules.
Designing to qualify and to perform
The grant is conditional on MCS-standard design, and that is also what makes the system actually work:
- Heat loss calculation room by room (MCS heat-loss methodology), not a rule-of-thumb sizing off the old boiler kW.
- Emitter sizing to a low flow temperature (typically 45–50 °C, lower is better) — many radiators need uprating; check compatibility before promising.
- Hot-water cylinder sized for the heat pump (larger coil, reheat times).
- Controls and commissioning records to MCS, which are required to redeem the voucher.
Under-design and the customer gets a cold, expensive-to-run system and a bad review; the MCS process exists to prevent exactly that.
Stacking and interactions
- BUS cannot be combined with the same earlier RHI payments on the same system.
- BUS can sit alongside other support such as ECO measures in some circumstances, and the 0% VAT on energy-saving materials (heat pumps qualify for 0% VAT to 2027) applies to the install — confirm current VAT rules with the customer's circumstances.
- Local authority schemes (e.g. Warm Homes / GBIS) may help with the insulation that improves heat-pump performance.
Frequently Asked Questions
Can a homeowner apply for the BUS grant themselves?
No. The Boiler Upgrade Scheme is deliberately installer-led: only an MCS-certified installer can register the job, request the voucher and redeem it. The homeowner gives consent and pays the discounted balance. This is different from some other grant schemes, so set the expectation early — the customer's "application" is really choosing an MCS installer.
Is it £7,500 off any heat pump?
It is £7,500 towards an MCS-certified air-source or ground-source heat pump up to 45 kW that replaces a fossil-fuel system in an eligible property. It is a fixed grant, not a percentage, so on a smaller install it covers more of the cost and on a larger one less. Biomass is a separate £5,000 grant restricted to rural off-gas properties.
Does the customer need to insulate the loft first?
The property needs a valid EPC, and there has historically been a rule about outstanding insulation recommendations on that EPC. Because this specific condition has changed during the scheme, check the current Ofgem BUS guidance before telling a customer they must insulate — but regardless of the grant rule, good loft and cavity insulation is strongly advisable so the heat pump can run at a low, efficient flow temperature.
Can BUS be used on a new build?
Generally no — new-build properties are excluded. The exception is eligible self-build homes (privately commissioned, not speculative developer stock). Standard new developments are expected to install low-carbon heating under building standards rather than via BUS.
How long does the voucher last?
Vouchers have a redemption window from issue — commonly around 3 months for air-source heat pumps and biomass and 6 months for ground-source (which take longer to install). The exact windows have been adjusted over the scheme's life, so confirm the current validity period when the voucher is issued and plan the install accordingly.
Regulations & Standards
Boiler Upgrade Scheme — Ofgem-administered grant scheme (The Boiler Upgrade Scheme Regulations 2022, as amended).
MCS (Microgeneration Certification Scheme) — installer certification and product standards; MIS 3005 (heat pumps) and MCS 003 design methodology.
RECC / HIES — consumer-protection codes required for MCS membership.
Building Regulations Part L — energy efficiency; heat-pump installs interact with EPC/SAP.
VAT (Energy-Saving Materials) — 0% VAT on qualifying heat-pump installs (to 2027).
Ofgem — Boiler Upgrade Scheme — official scheme rules and grant values.
GOV.UK — Apply for the Boiler Upgrade Scheme — homeowner-facing guidance.
MCS — Microgeneration Certification Scheme — installer certification and standards.
GOV.UK — VAT on energy-saving materials — 0% VAT relief.
bus grant scheme guide — companion heat-pump-focused BUS guide
mcs certification explained — what MCS is and how to become certified
heat pump sizing heat loss — the heat-loss design BUS requires
radiator heat pump compatibility — checking and uprating emitters for low flow temps
air source heat pump installation — installing the system the grant funds