Our views on BUS Grant being extended to domestic air conditioning

Expansion of the Boiler Upgrade Scheme: Air-to-Air Heat Pumps

The Government has recently expanded the Boiler Upgrade Scheme (BUS) to include air-to-air heat pumps (A2A) and heat batteries, providing homeowners with a wider range of low-carbon heating options. Originally focused on hydronic (wet) systems, the scheme now recognises the efficiency of air-to-air technology, particularly for properties where traditional radiator-based systems are impractical or where cooling is also a priority. This update aligns with the government’s broader strategy to decarbonise home heating and move away from fossil fuel dependency. This update came into force on April 28th 2026.

Boiler Upgrade Scheme Criteria for Air-to-Air Systems

To qualify for funding under the expanded BUS, both the property and the technology must meet specific eligibility requirements. The grant for an air-to-air heat pump is currently set at £2,500.

Property Eligibility

Location: The property must be located in England or Wales.
Ownership: Applicants must own the property, which can be a primary residence, a second home, or a property rented out to tenants.
Existing System: The new heat pump must replace an existing fossil fuel heating system (such as gas, oil, or LPG) or a direct electric heating system. It cannot be used to replace an existing low-carbon system.
No existing system: Despite its name BUS can be claimed for installing a heating system in a property where there was previously no central heating. Air to air can be a good option for this situation.
Exclusions: Social housing and most new-build properties are excluded, though custom-built “self-build” homes may qualify.
Technology Requirements
Space Heating: The system must be designed to provide space heating. While A2A units can provide cooling, the grant’s focus is on heating.
Whole Property Demand: The heat pump must be sized to meet the full space heating needs of the property, either on its own or in combination with other eligible electric appliances. Eligible appliances include an electric towel rail in a bathroom as it is not feasible to install an air to air unit in small rooms, such as toilets and bathrooms.
No Fossil Fuel Hybrids: The system must not be a hybrid that combines a heat pump with a fossil fuel boiler. You are expressly forbidden to retain your boiler!
Residential Focus: For air-to-air heat pumps specifically, the BUS funding is limited to installations in residential properties.

Pros and Cons of Air-to-Air Heat Pumps

Air-to-air heat pumps operate by extracting heat from the outside air with the help of refrigerants and distribute it directly into the home via fan units. This differs from air-to-water systems, which use heat to warm water for radiators or underfloor pipes.

Pros

• Provides both heating in winter and cooling in summer.
• Generally cheaper and less invasive; no need for new radiators or pipework.
• Heats up rooms very quickly and provides even air circulation.
• Ideal for flats, apartments, and open-plan spaces.
• Lower upfront cost compared to air-to-water heat pumps.
• Is a cost effective option if paired with solar PV for summer cooling

Cons

• Typically does not provide domestic hot water for taps or showers – though products are becoming available with hot water cylinders.
• May require multiple indoor units and ducting, which can be problematic for retrofit scenarios
• Performance can decline in exceptionally freezing temperatures.
• Less efficient for very large homes compared to hydronic systems.
• A2A is likely to be more expensive to use as central heating for a family size house partly because water is likely to be heated by direct electricity.

One of the most significant advantages of A2A systems is their dual functionality, acting as air conditioning during warmer months. However, because they do not heat water, homeowners must install a separate solution for domestic hot water, such as an electric immersion heater or a thermal battery.

Process for Installer Registration

The Boiler Upgrade Scheme is “installer-led,” meaning the property owner does not apply directly for the grant; instead, a registered installer handles the application and deducts the grant value from the final invoice.

MCS Certification

To be offered under the BUS scheme a product has to be registered with MCS and should be visible on the MCS Product Directory. Unfortunately at the time of writing in May 2026 there are no air to air products uploaded. This means that the grant is in practical terms not available yet.

Managing Customer Expectations

In addition to needing registered products to be available. The installer themselves will need to add air to air heat pump technology onto their MCS registration. This requires an assessment from their Certification Body. At a recent panel discussion at an industry event a representative of MCS could offer no concrete timescales for when Certification Bodies will be ready to assess installers against the new Air to Air Installation standards.

Application and Voucher Process

When it is up and running this is how the process will work:

Assessment and Quote: The installer assesses the property’s suitability and provides a quote that clearly shows the BUS grant as a deduction from the total cost.
Voucher Application: The installer applies for a BUS voucher via the Ofgem portal on behalf of the customer.
Customer Consent: Ofgem emails the property owner to confirm they have given consent for the installer to act on their behalf.
Voucher Issuance: Once approved, Ofgem issues a voucher to the installer.
Installation and Commissioning: The installer completes the work within the voucher’s validity period (typically 3 months for A2A).
Redemption: After commissioning the system and generating an MCS certificate, the installer redeems the voucher through their Ofgem account to receive the grant payment directly.

Conclusion

Our ‘Warm Wisdom’ is telling us – don’t count on there being a huge upsurge in MCS registered Air to Air installers being available in the short term. If you need a new heating system quite urgently it is probably best to look at other options such as an air source heat pump.

It is worth having a conversation with local MCS registered installers and ask them if they are planning to add air to air onto their list of registered technologies. Don’t be surprised if their response is a bit ‘luke warm’.

If you are actually interested in cooling for rooms that get overheated in hot weather, this can make a real difference to comfort, but won’t be covered by the BUS grant so enquire with local companies safe in the knowledge that you’re not missing out on any grant funding.

Louise Howlett