Boiler Upgrade Scheme (BUS)

Scheme eligibility

This page summarises key information about the Boiler Upgrade Scheme (BUS) for installers.
For full scheme details, we encourage you to read the BUS installer guidance.

To apply for a grant on behalf of a property owner, your business must be certified to install the relevant technology with the Microgeneration Certification Scheme (MCS), or equivalent scheme should one become available.

Some of the eligibility criteria for the scheme are set out below. For a full explanation of all eligibility criteria, see chapter 2 of BUS: installer guidance.

In order to be eligible for a BUS-funded installation a property must:

  • be in England and Wales
  • comply with the insulation requirements of the scheme, or be shown to be exempt from these
  • not be social housing
  • not be a new build (although ‘self builds’ are eligible, providing they’ve been built mainly using the labour or resources of the first owner and have never been owned by a business or organisation)
  • (retrofits only) have an existing fossil-fuel or electric heating system that’s being replaced by the BUS-funded installation  

For the full set of eligibility criteria related to properties, please read the BUS: installer guidance.

The following technologies are eligible for the BUS:

  • air source heat pumps (air-to-water)
  • ground source heat pumps
  • ground source heat pumps as part of a shared ground loop
  • biomass boilers

The requirements that apply to all technology types are that the heating system:

  • complies with the BUS regulations and the relevant MCS standards approved by the Secretary of State.
  • has a maximum capacity of 45 kWth (including a system limit of 45 kWth for shared ground loops)
  • is commissioned on or after 1 April 2022
  • is new - none of the heat-generating components of the new heat pump or biomass boiler have been used prior to commissioning (ground source heat pumps can connect to an existing shared ground loop, providing the heat pump is new).
  • replaces all parts of the main heating system that generate heat via fossil fuels (though you don’t need to have replaced any circulation pumps, solar thermal collectors, supplementary electric heaters or wood-burning stoves).
  • is capable of meeting the full space and water heating demands of the property
  • has not been the subject of another grant from public funds to cover any of the purchase or installation costs
  • has not been funded by the Energy Company Obligation (ECO)
  • will be owned by the property owner at the installation address after it is installed

An additional requirement for heat pumps only is that they: 

  • have a minimum seasonal coefficient of performance (SCOP) rating of 2.8

In addition, biomass boilers:

  • can only be installed in rural properties 
  • can only be installed in properties with no connection to the gas grid
  • cannot be installed in self-builds
  • must have an emissions certificate to show they meet certain emissions standards for the scheme

For a full explanation of all eligibility criteria, see chapter 2 of BUS: installer guidance.

How the scheme works


1. You will need to create a BUS installer account in order to be able to submit BUS applications. Instructions on how to do this can be found on the BUS ‘Sign up and apply’ page.


2. You advise the property owner on whether a proposed installation is eligible for a grant.
3. Together, you agree a quote for the project.
4. You also both agree that you can submit a BUS voucher application on behalf of the property owner.

Application and property owner consent

5. You apply for the BUS voucher on behalf of the property owner.
6. Ofgem then emails the property owner and asks them to confirm that you have agreed they can submit a voucher application on their behalf. Property owners will also confirm some details related to their eligibility, including that they’re aware they may need to address any issues with their EPC.
7. After conducting eligibility checks, Ofgem emails you a voucher for the grant amount.

Installation and commissioning

8. From the date the voucher is issued, you have 3 months to complete the installation (6 months for a ground source heat pump). If the voucher expires before you have commissioned the installation, you can re-apply for another BUS voucher - go back to Step 5.

Voucher redemption and payment

9. After you've commissioned the new system and generated the MCS installation certificate, you can apply to Ofgem to redeem your voucher.
10. Ofgem conducts final eligibility checks, which will include at a minimum reviewing the details on the MCS installation certificate.
11. Once a redemption application has been approved, it will be processed for payment, along with all other redeemed vouchers, on the next scheduled payment day. Scheduled payment days will occur on a weekly basis.

Audit and compliance

To ensure installers comply with scheme regulations, Ofgem has the power to conduct audits and take action where non-compliance is suspected or discovered.

These can be either site or desk audits and can occur at any point after you've made a BUS application, including after you’ve been paid the grant.

For full details of our audit and compliance powers and activities and how they affect you, see see chapter 8 of the BUS: installer guidance.