Air-to-Air Heat Pump UK: Grant Status, Cost and Limits

Air-to-Air Heat Pump UK: Grant Status, Costs and How It Differs From Air-to-Water

Air-to-air heat pumps have gone from a niche idea to one of the most searched heating topics in the UK. The reason is the government’s decision to extend the Boiler Upgrade Scheme to cover them, with a £2,500 grant. But between the announcement and a homeowner actually claiming it, there’s a gap that a lot of websites don’t mention.

This guide explains what an air-to-air heat pump is, how it differs from the air-to-water systems most people mean when they say “heat pump”, what the grant situation really is as of October 2026, what it costs, and whether it suits your home.

The Short Answer

An air-to-air heat pump heats (and cools) your rooms by warming the air directly, using indoor units like those on an air conditioning system. It doesn’t heat radiators or hot water. The government has approved a £2,500 Boiler Upgrade Scheme grant for eligible systems in England and Wales, but as of mid October 2026 it can’t be claimed yet, because the grant requires an MCS-certified installer and none are available for air-to-air. MCS expects certification before the end of 2026. Typical costs are far lower than for an air-to-water system, but you also get less: no radiators and usually no hot water.

What Is an Air-to-Air Heat Pump?

Both types of air source heat pump pull heat from outside air. The difference is where the heat goes.

• An air-to-water heat pump (the type most UK installers mean) heats water, which then flows through radiators or underfloor heating and into a hot water cylinder. This is the “wet” central heating system.

• An air-to-air heat pump skips the water entirely. It moves heat from the outside air into the room air through refrigerant pipes running between an outdoor unit and one or more indoor units, usually mounted high on a wall.

It’s the same technology as a reverse-cycle air conditioning system. Many air conditioners can heat as well as cool. That’s why the two are so often confused. If you’d like a deeper look at how cooling compares, see our guide on whether heat pump cooling is better than air conditioning.

Air-to-Air vs Air-to-Water: The Main Differences

The Three Main Types of Air-to-Air System

Split and multi-split systems. One outdoor unit connects to one or more indoor units. This is the most common type. Each additional indoor unit means more pipework, usually run in slim trunking along the upper edges of the room.

Ducted systems. A central unit, often about the size of a boiler, sits in a loft or utility room and moves warm air through ducts hidden in ceiling voids. These can be harder to fit in older or larger homes because the ductwork needed to carry enough heat can become large.

All-in-one (monobloc) systems. Everything sits in a single indoor unit that draws outside air through two small ducts in an external wall, typically 15 to 20cm wide. These suit homes where an outdoor unit can’t go, and they’re a relatively new option.

Is the £2,500 Air-to-Air Grant Available Yet?

This is the question behind the 1,000 searches a month, and the honest answer is: not yet.

What’s confirmed. The government expanded the Boiler Upgrade Scheme to include air-to-air heat pumps, and Ofgem now lists a £2,500 grant for residential properties. Industry sources say the regulations changed in April 2026.

Why it can’t be claimed. The scheme only pays out for installations by an MCS-certified installer using eligible, MCS-registered equipment. The Energy Saving Trust’s guide, last updated on 16 October 2026, says there are currently no MCS-certified installers for air-to-air heat pumps and that MCS expects certification to be available before the end of 2026. MCS has been updating its standards (including its product standard, performance estimate and design and installation standards) to cover air-to-air. More than 50 MPs have also written urging MCS to speed this up.

Who’s eligible, once it opens. Based on the scheme rules, you’d need to:

• Own the property, in England or Wales (Scotland and Northern Ireland have different support)

• Currently heat the property with a fossil fuel system, such as a gas boiler, or electric heating without a heat pump

• Use an MCS-certified installer, who applies for the grant and deducts it from your quote

What to do now.

• Be sceptical of any installer or website that says the grant is available today and asks for a deposit on that basis.

• If you install an air-to-air system before certification exists, assume the grant won’t apply, unless the installer confirms in writing how it could be claimed.

• Check Ofgem, GOV.UK and MCS for updates before paying anything.

If the grant is your main reason for a heat pump, note that the £7,500 grant for air-to-water heat pumps is available now, which can change the numbers significantly.

How Much Does an Air-to-Air Heat Pump Cost?

The Energy Saving Trust’s research suggests roughly:

• £1,900 to heat a single room

• £3,700 to heat a three-bedroom semi-detached house

Other costs, such as redecorating after installation, may be extra. If the £2,500 grant becomes available and you qualify, the three-bed example would come to about £1,200, though that is an illustration, not a quote.

For comparison, an air-to-water installation typically costs £8,000 to £15,000 or more before any grant, as covered in our guide to heat pump installation costs in the UK. That’s a bigger investment, but it heats the whole house, supplies hot water and replaces your boiler entirely. The two aren’t like-for-like.

Running costs. There isn’t much UK data on how air-to-air systems perform, so it’s hard to say how much you’d save. It depends on what you’re replacing, how well the system is designed and how you use it. Ask your installer for a running cost estimate based on your own home, and for how they worked it out. Our guide on heat pump running costs against gas and oil explains how to compare.

The Hot Water Question

This is the part people forget. Most air-to-air systems don’t heat water for your taps and shower, so you need a separate answer. The options include:

• A hot water cylinder with an immersion heater

• An electric shower and point-of-use water heaters

• An air-to-air model that also heats a cylinder (a small number of manufacturers offer this)

• Solar water heating, if you have the space, usually backed by an immersion heater

Each option has its own cost and running cost, and it should be part of your comparison. Our article on whether you need a hot water cylinder with a heat pump covers the cylinder side.

Why Design and Sizing Still Matter

It’s tempting to think air-to-air is simpler. The technology is simpler to install, but good heating performance still depends on sizing and design.

Size for heating, not just cooling. Many installers of air conditioning size units for cooling. If heating is your main reason for buying, the system needs to be designed and sized for your heating needs, and an installer with experience of designing for heating, not only cooling. Ask to see how they calculated it.

Heat loss still decides everything. A room-by-room heat loss calculation tells you how much heat each room needs on the coldest days. Our guide on how a heat loss calculation works explains why.

Heat only reaches rooms with a unit. In a wet system, every room with a radiator gets heat. In an air-to-air system, rooms without an indoor unit rely on heat moving through doorways, so layout and door use matter.

Low outdoor temperatures reduce output. Check the manufacturer’s heating capacity at your design temperature, not just the headline figure.

Noise and ventilation. Indoor units can be noisier than other heat pump types, and air-to-air systems recirculate the air already in your home rather than bringing in fresh air, so ventilation still matters. Our guide on heat pump noise covers what’s normal for outdoor units.

Who Air-to-Air Suits (and Who It Doesn’t)

It can suit:

• Flats and smaller homes, particularly without wet heating

• Homes with electric heating, such as storage heaters

• Extensions or single rooms that need heating and cooling

• Homes with limited outdoor space, where a monobloc or small outdoor unit works

• Households that want cooling as well as heating

It may not suit:

• Larger or older homes with high heat loss, especially where ducting is impractical

• Households that want one system for heating and hot water

• People who dislike indoor units on their walls

• Homes where the heat wouldn’t reach the rooms that matter most

For larger homes, an air-to-water system is usually the better fit, and in some homes a hybrid heat pump system is a third option. If you’re choosing between air and ground source systems instead, see air source vs ground source heat pumps.

Air-to-Air vs Air Conditioning, and Planning Permission

The technology is the same family, but only systems that meet the scheme’s requirements will qualify for funding, and the design needs to suit heating. Planning rules for outdoor units can also apply. See our guides on planning permission for a heat pump and whether your existing air conditioning counts as a heat pump for planning. Rules differ by area and change, so check with your local authority before you buy.

How to Decide: Six Questions to Ask

1. Do I need hot water as well as heating? If yes, air-to-air needs a separate solution.

2. Do I have, or want, radiators? If you already have wet heating, air-to-water usually makes more sense.

3. How big is my home, and how high is its heat loss? Larger, leakier homes favour air-to-water.

4. Do I want cooling? That favours air-to-air, though our heat pump cooling assessments look at cooling for air-to-water systems.

5. Is the grant central to my decision? The £7,500 grant for air-to-water is claimable now. The £2,500 for air-to-air is not.

6. Has anyone calculated my heat loss? Without it, any system size is a guess.

Before you sign anything, check how the quote compares. Our guide on how to compare heat pump quotes lists what a good quote includes, and one of our case studies shows a homeowner working out which of two quotes was the better design.

Frequently Asked Questions

Is the air-to-air heat pump grant available?
The £2,500 grant has been approved under the Boiler Upgrade Scheme, but as of mid October 2026 it can’t be claimed because no MCS-certified installers are available for air-to-air. MCS expects certification before the end of 2026. Check Ofgem, GOV.UK and MCS for updates.

How much is the air-to-air heat pump grant?
£2,500 for eligible systems in residential properties in England and Wales. Scotland and Northern Ireland have different support.

How much does an air-to-air heat pump cost in the UK?
Energy Saving Trust research suggests around £1,900 for a single room and around £3,700 for a three-bedroom semi-detached house, with other costs such as redecoration possible.

Does an air-to-air heat pump heat water?
Usually not. You’ll need a separate way to heat hot water, such as an immersion cylinder, electric shower, solar water heating or a model that heats a cylinder.

Is an air-to-air heat pump the same as air conditioning?
They use similar technology, and many air conditioners can provide heating. For heating, choose a system designed and sized for it, not just for cooling.

Are air-to-air heat pumps worth it?
It depends on your home. They can work well in flats and smaller homes without wet heating. UK performance data is limited, so ask your installer for a running cost estimate for your own home.

Do air-to-air heat pumps work in winter?
They’re designed to heat, but output falls as it gets colder. Check the heating capacity at your design outdoor temperature, and make sure the system was sized from a heat loss calculation.

Can I get the grant if I install now?
Not unless the installation meets the scheme requirements, which include an MCS-certified installer. Don’t pay on the assumption you can claim later without written confirmation.