Air-to-air vs air-to-water: why the grants are different
The two grant levels
The Boiler Upgrade Scheme pays £2,500 towards an air-to-air heat pump in a residential property, and £7,500 towards an air-to-water or ground-source heat pump. Both are government grants under the same scheme; the amount depends on the type of system installed.
The £7,500 figure gets quoted more often online because it's the older, headline number. If you're searching for an air-to-air grant, £2,500 is the figure that applies to your install.
See which grant applies to your home — five questions.
Check eligibilityWhat each system actually does
An air-to-air heat pump is the wall-mounted unit most people call air conditioning. It moves heat between the outside air and the air in your rooms — cooling in summer, heating in winter. It doesn't heat water.
An air-to-water heat pump heats water in a cylinder, which then feeds your radiators (or underfloor heating) and your hot taps. It replaces a gas boiler like-for-like on the water side. Ground-source systems do the same, but draw heat from pipes buried in the garden.
Why the grant differs
Air-to-water and ground-source installs are more disruptive and more expensive: bigger unit, cylinder, sometimes new radiators, and days of pipework. The £7,500 grant reflects that cost.
Air-to-air is a smaller job — outdoor unit, indoor head, refrigerant line between them. It costs less to install, which is why the grant is set lower at £2,500. It also means your existing hot water arrangement needs a separate plan; see our guide on hot water for the options.
Which one fits your home
If you want cooling in summer as well as heating, or you live in a flat where running new pipework is impractical, air-to-air is usually the right answer. If you already have wet central heating and want to replace the boiler directly, air-to-water is normally the better match.
An MCS-certified installer will assess your home and quote for the system that suits it, applying for the correct grant on your behalf.