An air-to-air heat pump heats your rooms directly with warm air from discreet wall-mounted units, instead of pumping hot water through radiators. If you've stayed anywhere warm abroad, you've used one — and in summer it runs in reverse, cooling the same rooms it heats in January. Until this year it was the heat pump the grant system ignored. That changed in April 2026, and for the right property it's now the cheapest route out of fossil-fuel heating there has ever been.
What Changed in April 2026
The Boiler Upgrade Scheme originally covered only "wet" systems — air-to-water and ground source heat pumps feeding radiators. From April 2026, air-to-air heat pumps became eligible for the first time, with a grant of £2,500 for residential properties. The conditions mirror the main scheme: the system must be fitted by an MCS-certified installer, and it must fully replace your existing fossil fuel or electric heating — the old boiler or heaters go, they don't stay as backup. The application is installer-led, exactly as with the bigger grants: we apply to Ofgem, the £2,500 comes off your invoice, and you pay the difference. Full scheme detail lives on our Boiler Upgrade Scheme hub.
For the fine print — who qualifies, how air-to-air compares against the £7,500/£9,000 air-to-water route, and why the answer isn't always the bigger grant — see our air-to-air grant guide.
What It Costs — Sometimes Nothing
For wider context, installed prices for every property type — with the grant maths worked through in three scenarios — are in our heat pump cost guide, and the running-cost comparison against oil, LPG, gas and electric heating is in the running costs guide. The short version for this page:
Air-to-air is by far the cheapest heat pump to install because there's no cylinder, no radiator changes and no wet pipework. A single-zone system — one outdoor unit serving one indoor unit, right for a flat, an open-plan living space or an extension — typically costs £2,500–£4,500 installed. Set the £2,500 grant against that and the smallest jobs genuinely come out at £0; most single-zone installs land between £0 and £2,000 out of pocket. Multi-room systems, with one outdoor unit feeding three to five indoor units, typically run £5,000–£9,000 before the grant. VAT is 0% on all of it until 2027.
| System | Before grant | After £2,500 grant |
|---|---|---|
| Single zone (1 indoor unit) | £2,500–£4,500 | £0–£2,000 |
| Two–three rooms (multi-split) | £5,000–£7,000 | £2,500–£4,500 |
| Whole small home (4–5 indoor units) | £7,000–£9,000 | £4,500–£6,500 |
Heating and Cooling in One System
This is the feature no radiator system can match. The same unit that heats a room in January cools it in July — real, thermostat-controlled air conditioning, not a fan. Recent Bucks summers have made south-facing bedrooms and loft conversions genuinely hard to sleep in; an air-to-air system solves winter and summer with one piece of kit, using the same efficient refrigeration cycle in both directions. Cooling costs pennies per hour, and in heating mode efficiency matches or beats wet heat pumps because there's no water loop in the middle — typical output is 3–4 kWh of heat per kWh of electricity. If you were considering air conditioning anyway, the grant effectively pays you to buy the version that also heats.
Installation is the lightest-touch of any heat pump. The outdoor unit connects to each indoor unit by slim refrigerant lines run through a 65 mm wall hole and neat external trunking — no wet pipework through the house, no floorboards up. Indoor units mount high on the wall, need a small condensate drain, and are fitted by F-gas certified engineers; a single-zone job is typically finished, commissioned and demonstrated within a day.
Which Properties Suit Air-to-Air
The honest sorting question is hot water and room count. Air-to-air shines where heating demand is compact and water heating is easy to solve separately: flats and apartments (with freeholder consent for the outdoor unit), well-insulated smaller homes and bungalows where two or three indoor units cover the living space, extensions, annexes and garden rooms that the existing boiler never reached, and all-electric homes replacing storage heaters — where it's transformative, since storage heaters cost two to three times as much per unit of heat.
Where we'll talk you out of it: a four-bed family house with a bathroom-heavy morning routine is usually better served by an air-to-water heat pump — one indoor unit per room adds up fast, and the £7,500–£9,000 grants on the wet system usually beat the £2,500 here. We quote whichever route leaves you better off; sometimes that's both options side by side.
Air-to-Air Questions
Does an air-to-air heat pump do hot water?
No — it heats and cools rooms only. Showers and taps need a separate solution, usually a well-insulated immersion cylinder on a cheap overnight tariff, or whatever you already have. We include this in the design and the quote so there are no surprises; it's also the main reason larger households often do better with air-to-water.
Is it noisy — inside or out?
Indoor units run at 19–30 dB on low — quieter than a library. The outdoor unit is smaller and quieter than an air-to-water unit and sits comfortably within permitted development noise limits in almost every garden. The same siting rules apply: we run the MCS noise assessment before anything is fixed to a wall.
Can I get the £2,500 grant for a system that only cools?
No. The grant exists to replace heating systems, so it applies when the air-to-air system becomes your home's heating and your old fossil-fuel or electric heating is fully removed. A unit added purely for summer cooling, with the boiler staying, is a normal paid installation — worth having, but not granted.
I rent out a flat — can I use the grant there?
Yes. Landlords and second-home owners qualify for the Boiler Upgrade Scheme, and air-to-air suits rental flats particularly well: low install cost, no wet system to maintain, and tenants get cooling. You'll need freeholder consent for the outdoor unit on leasehold properties — we handle the technical drawings that request usually needs.
How long does installation take?
A single-zone system is usually done in a day; multi-room systems take two. There's no pipework through the house beyond the slim refrigerant lines, so it's the least disruptive heat pump installation there is — no floors up, no radiators off the walls.
Find Out Which Heat Pump Your Home Actually Wants
Tell us about your property and we'll give you a straight answer — air-to-air with the £2,500 grant, air-to-water with £7,500–£9,000, or both quotes side by side so you can see the arithmetic yourself.