The 2026 change in plain English
From 28 April 2026, the Boiler Upgrade Scheme expanded to include a £2,500 grant towards an eligible air-to-air heat-pump installation in a residential property. Ofgem administers the scheme in England and Wales. The grant is not a general discount on any wall-mounted air conditioner: the property, installer, system design and application must satisfy the current scheme rules.
Air-to-air systems move heat between outdoor and indoor air and distribute heating through indoor fan units rather than a wet radiator circuit. Reversible models may also cool. That makes them relevant to flats and smaller homes, but they normally do not provide domestic hot water. The whole heating and hot-water plan should therefore be clear before a quotation is accepted.
Eligibility begins with the property and existing heating
Ofgem says the air-to-air grant is for residential properties. BUS generally supports eligible installations in England and Wales and excludes social housing and most new-build properties, apart from qualifying self-builds. For retrofit work, the funded installation must replace an existing fossil-fuel or electric heating system. A valid EPC number may be needed, or the installer must provide alternative evidence where the scheme allows it.
Do not assume that receiving another energy grant automatically confirms or prevents BUS eligibility. Funding interactions, ownership status, previous low-carbon heating and the exact system configuration can affect an application. Use Ofgem's current property-owner guidance and ask the proposed MCS-certified installer to identify the precise rule relied upon in writing.
The installer applies, but the owner still checks
BUS is installer-led. An installer certified under the Microgeneration Certification Scheme for the relevant technology applies for and redeems the voucher. Ofgem then contacts the property owner for consent and identity checks. A quotation should show the full grant as an upfront discount; the installer must not ask the owner to pay the grant value and wait for reimbursement.
Ask for the installer's legal business name, MCS certification details, the exact outdoor and indoor models, a room-by-room design, noise assessment and the proposed application timetable. A badge on a sales page is not enough. Certification, product eligibility and property eligibility are separate checks, and a product appearing on a list does not by itself guarantee that the installation qualifies.
Compare the net project, not only the grant
The useful comparison is the total installed price minus the confirmed grant, with every excluded item still visible. Quotes should identify electrical upgrades, condensate routes, core drilling, access equipment, controls, making good and any planning or freeholder work. A grant can improve affordability without making a poorly designed system good value.
Model annual running cost using a stated heat demand, seasonal performance assumption and the household's electricity tariff. Cooling use should be shown separately because it is an additional service and additional electricity demand. Compare at least two itemised quotations on the same room scope and retain the version and date of every grant assumption.
Important dates and the £9,000 headline
The separate temporary £9,000 BUS amount applies to eligible air-to-water or ground-source heat pumps in qualifying off-gas-grid properties replacing oil or LPG; Ofgem states that uplift is available from 21 July 2026 until 31 March 2027. It is not the air-to-air grant. Air-to-air heat pumps have a published £2,500 grant value, including for qualifying off-gas properties.
Rules and guidance can change, so check the application date rather than relying on an old article or quotation. CoolCompare's Grant Tracker records the official source, effective period and next review date. Treat this guide as a route into the current evidence, not as an eligibility decision or promise that a voucher will be issued.
Check that the funded design covers the whole heating job
Ofgem’s property-owner guidance requires the proposed installation to satisfy the scheme’s whole-property heating conditions. That makes a BUS installation different from adding one reversible wall unit to the room that happens to overheat most often. Ask for the room-by-room heat-loss assumptions, intended indoor-unit locations and an explanation of how closed bedrooms, halls and other separated spaces will be heated. If parts of the home rely on heat drifting through open doors, that design limitation should be visible before the contract is signed.
Air-to-air heat pumps do not normally produce domestic hot water, so the quotation should identify the separate hot-water arrangement and its energy source. Ask the installer to map every retained or proposed heater against the versioned scheme rules rather than relying on a general statement that the property is heat-pump ready. The answer should explain the complete heating configuration, not only the equipment receiving the grant.
Keep the grant journey auditable from quote to final invoice
Keep one file containing the installer’s legal name, MCS certificate details, initial survey, heat-loss evidence, exact model schedule, full pre-grant price and the grant shown as a separate upfront deduction. Retain the property-owner consent message and any voucher correspondence. The final invoice should preserve the same distinction between project cost and grant value. The owner should not be asked to finance the grant amount temporarily, and an unexplained special discount is not a transparent substitute for identifying BUS.
Record every later change to equipment, indoor-unit count, installation scope or price. Ask whether the revised design affects eligibility or requires the application evidence to be updated before commissioning. Preserve the official rule URL and access date used for the decision, because an old quotation can otherwise be mistaken for current guidance. Scheme support does not certify that a price is competitive or that a design suits the home; those remain separate quotation, survey and consumer-protection checks.
Build a grant evidence file before comparing net prices
Create one dated file for the proposed system before treating an advertised grant as money available to the project. Record the property and tenure, present heating and hot-water systems, proposed technology, exact indoor and outdoor equipment, installer identity, relevant certification, scheme rule version and the official source used on that date. Keep the full price before grant, the grant amount, the customer balance and every excluded electrical, access, drainage, making-good or permission item on separate lines. The air-to-air route must not inherit an amount or condition from another heat-pump category merely because both products contain the words heat pump. Ask who applies, who receives the scheme payment, what evidence is needed, what happens if approval is refused or expires, and whether ordering equipment creates a non-refundable commitment. A retailer discount, installer promotion or finance contribution should retain its own label instead of being made to look like public funding.
Recheck the file at three points: before a deposit, before equipment is ordered and before final payment. At each point confirm that the scheme remains open for the relevant nation and technology, that the installer and proposal still meet the stated route, and that no equipment or scope substitution has changed the answer. Save application references, eligibility communications, revised quotations and the final commissioning or scheme evidence; do not overwrite the earlier version because it explains which rule informed the decision. Compare competing quotations first on their complete pre-grant scope, then on the same confirmed grant assumption, and finally on the household’s payable balance and retained systems. This prevents one quote appearing cheaper only because it omits hot water, electrical work or another room. CoolCompare’s checker can organise these questions, but it cannot award funding or give legal certainty. The official administrator and the facts of the live application remain decisive, particularly where rules, budgets and temporary provisions can change after an article was reviewed.
