Boiler Upgrade Scheme (BUS) Guide: £7,500 ASHP Grant, Eligibility, Application Process and Installer Obligations

Quick Answer: The Boiler Upgrade Scheme (BUS) provides £7,500 for replacing a fossil fuel heating system with an air source heat pump (ASHP) or ground source heat pump (GSHP) in England and Wales. The customer applies for a voucher through Ofgem, the installer (who must be MCS-certified) installs the heat pump, and then redeems the voucher — reducing the customer's invoice by the grant amount. Key eligibility: valid EPC with no outstanding loft or cavity wall insulation recommendation; replacing a fossil fuel (gas, oil, LPG) primary heating system; property in England or Wales.

Summary

The Boiler Upgrade Scheme launched in April 2022 as the UK government's primary demand-side heat pump incentive for domestic and small commercial properties. It provides a straightforward capital grant — the customer does not pay the grant amount; the installer claims it and reduces the invoice accordingly.

For heat pump installers, BUS vouchers are the primary route through which customers can afford heat pump installations. Understanding the eligibility rules, the application timeline, and the installer obligations is essential for every heat pump installer.

Key Facts

Quick Reference Table: BUS Eligibility

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Criterion Eligible? Notes
ASHP installation Yes — £7,500 grant MCS certified; England/Wales
GSHP installation Yes — £7,500 grant MCS certified; England/Wales
Existing gas boiler being replaced Yes Must be the primary heating system
Existing oil boiler being replaced Yes Must be the primary heating system
No valid EPC No Must have EPC; apply at epcregister.com
EPC has outstanding insulation recommendations No Must first address loft/cavity wall insulation
New build property No BUS for retrofits only
Commercial premises (large) No BUS is for domestic and small non-domestic
Scotland No — separate scheme Apply to Home Energy Scotland

Detailed Guidance

How the Application Process Works

Step 1: Customer checks eligibility The customer (homeowner or landlord) checks their EPC on the EPC register (epcregister.com). The EPC must:

If the EPC is expired, a new EPC is required (cost: £60–£120). If the EPC includes outstanding insulation recommendations, these must be addressed first (or the customer can contest the recommendation if the insulation has already been installed).

Step 2: Customer applies for a BUS voucher The customer applies through Ofgem's BUS portal. The application requires:

Vouchers are usually issued within a few days of application. The voucher specifies the grant amount and the validity period.

Step 3: Installer completes the installation The MCS-certified installer carries out the heat pump installation fully compliant with MCS 007:

Step 4: Installer redeems the voucher The installer redeems the BUS voucher through the Ofgem BUS portal. Required information:

On successful redemption, the grant (£7,500) is paid directly to the installer by Ofgem within a defined payment period (typically 10–15 business days).

Step 5: Invoice to customer The installer invoices the customer for the full installation cost minus the £7,500 BUS grant. The invoice must show:

EPC Insulation Recommendations: The Key Barrier

The most common reason for BUS ineligibility is an outstanding EPC recommendation for loft or cavity wall insulation. If the EPC recommends either of these and they have not been installed, the BUS application will be rejected.

How to address this:

  1. Check the EPC recommendations section carefully — it lists measures by category
  2. If loft insulation is recommended: the customer must either install loft insulation (typically £300–£500 — much cheaper than losing the £7,500 grant) or obtain evidence that the loft already has adequate insulation
  3. If cavity wall insulation is recommended: the customer must either install it (£500–£1,500 for a typical semi-detached) or provide evidence that the property's walls are not suitable for cavity wall insulation (solid walls, filled cavities, non-standard construction)

Cavity wall insulation suitability survey: Where the EPC recommends cavity wall insulation but the walls are already filled, solid, or otherwise unsuitable, a CIGA (Cavity Insulation Guarantee Agency) registered surveyor can confirm the walls are unsuitable. This confirmation can be submitted as part of the BUS application to remove the outstanding recommendation from the eligibility assessment.

Updated EPC: If insulation has been installed since the existing EPC was issued, a new EPC (updated to reflect the installed insulation) will remove the recommendation and restore eligibility.

Installer Obligations Under BUS

Grant paid to installer — not customer: The BUS framework requires the grant to be paid to the installer, not the customer. The installer then reduces the customer's invoice. The installer cannot simply pocket the grant — this is fraud and would result in removal from the MCS scheme and potential criminal liability.

MCS 007 compliance: All BUS installations must comply with MCS 007. If an audit reveals non-compliance (e.g., no heat loss calculation was performed, heat pump is significantly oversized, commissioning records are incomplete), the installer faces compliance action from the certification body and potential grant clawback.

Voucher redemption timeline: The voucher must be redeemed within its validity period (check current rules — validity has varied). If the installation is delayed and the voucher expires, the customer must apply for a new voucher. New vouchers are subject to current scheme availability — if the scheme's annual budget is exhausted, new vouchers may not be available until the next funding period.

Ongoing audit exposure: BUS-funded installations are included in the MCS audit pool. An installer who claims multiple BUS grants without adequate MCS 007 documentation is at higher risk of audit selection and findings.

BUS vs ECO4 and Other Schemes

BUS (Boiler Upgrade Scheme):

ECO4 (Energy Company Obligation):

Great British Insulation Scheme (GBIS):

For customers who qualify for ECO4, this may be more advantageous than BUS (full funding rather than a £7,500 partial grant). As an installer, being able to advise customers on all available schemes is a differentiator.

Commercial Properties

BUS for small non-domestic premises (small commercial, community buildings) was included in earlier iterations of the scheme. Check current Ofgem documentation for the current status of non-domestic BUS applications, as the scheme focus may have changed.

Frequently Asked Questions

The customer's EPC is 11 years old. Can they still apply for BUS?

No. The EPC must be less than 10 years old at the time of the BUS voucher application. The customer must commission a new EPC (typically £60–£120 from an accredited assessor). A new EPC may also update insulation recommendations if work has been done since the last assessment.

Can a customer apply for BUS if they also want to keep their gas boiler as a hybrid backup?

A hybrid heat pump system (heat pump + gas boiler backup) can qualify for BUS provided the heat pump is the primary heating system. The BUS documentation confirms this — "hybrid" installations are eligible. The heat pump must be the dominant heating source; the gas boiler is for backup/top-up only. Both the heat pump and the boiler must be serviced and maintained separately.

What happens if the installation fails an MCS audit after the BUS grant has been paid?

If an MCS audit finds the installation does not comply with MCS 007, the certification body will require remedial action. In serious cases, the grant payment may be subject to clawback by Ofgem. The installer bears the cost of remedial work; the customer's heat pump remains installed but the installer may face financial penalties.

My customer is in Scotland. Can they claim BUS?

No. BUS applies to England and Wales only. In Scotland, heat pump support is available through Home Energy Scotland (Scottish Government funded): interest-free loans and grants up to £7,500 (matching the BUS amount) for eligible properties. The customer should contact Home Energy Scotland (homeenergyscotland.org) for details.

Regulations & Standards