Air-to-air heat pumps

How it works

An outdoor unit takes heat from the outside air, and one or more indoor units blow warm air into the room. Running in reverse, the same system can cool. A single-split system has one indoor unit; a multi-split system serves several rooms but needs more pipework.

Most air-to-air systems do not provide hot water, so you will still need another way to heat water, such as an immersion heater or an existing boiler.

Costs and the grant

Energy Saving Trust puts the cost of heating a single room at around £1,900. Whole-home systems cost more.

The Boiler Upgrade Scheme offers £2,500 towards an air-to-air heat pump in a home in England or Wales, effective from 21 July 2026. Your installer applies. Check the current amounts and rules on our heat pump grants page.

Check

What to check first

• How you will heat water, since most systems do not.
• Where the indoor units go, and whether you are happy with wall-mounted units in living rooms.
• Where the outdoor unit goes, and whether planning rules apply to its position.
• Whether the installer is MCS certified, which the grant requires.

Do

Practical next steps

1. Decide which rooms you want heated, and whether you would use cooling.
2. Get quotes that state the heat output of each indoor unit and how hot water will be provided.
3. Compare running costs with your current heating in the heat pump calculator.
4. Check grant eligibility in the support finder.

Take care

Important limitations

• Using cooling adds to your electricity use.
• Warm air heating feels different from radiators; air movement and fan noise suit some people better than others.
• A grant announcement is not the same as funding being available for your home: check the official page before you commit.

Related tools and guides

• Heat pump grants
• Heat pump running costs
• Cheapest ways to heat one room

Sources

• Energy Saving Trust: air-to-air heat pumps
• GOV.UK: Boiler Upgrade Scheme, what you can get

Official sources checked 2 October 2026.