Air conditioning vs
air source heat pump
These are the same technology wearing two names, and the confusion costs people real money. Both are heat pumps. The difference is what they move the heat into: air, or water.
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An air conditioner is an air-to-air heat pump: it heats and cools rooms directly and costs 1,750 to 2,900 pounds a room. An air source heat pump usually means air-to-water: it heats radiators and hot water and does not cool. The Boiler Upgrade Scheme lists 7,500 pounds for the air-to-water system and, since 2026, 2,500 pounds for the air-to-air one.
Which is right depends on whether you want cooling at all, and on whether you are replacing a boiler or adding to one.
Side by side
| Air conditioning (air to air) | Heat pump (air to water) | |
|---|---|---|
| What it heats | The air in the rooms it serves | Radiators, underfloor, and hot water |
| Does it cool? | Yes, that is the other half of it | No |
| Hot water | No | Yes |
| Replaces the boiler? | No | Yes, that is the point of it |
| Government grant | £2,500 Boiler Upgrade Scheme, conditions apply | £7,500 Boiler Upgrade Scheme |
| VAT | 20% | 0% on installation |
| Cost | £1,750 to £2,900 per room | From the heat loss survey |
| Disruption | One day a room. No pipework changes | Radiators, cylinder, pipework |
| Best for | Cooling, plus cheap top-up heat room by room | Getting off gas entirely |
Every figure on this site is an estimate based on published UK market ranges and our own installation experience. It is not a quotation. The price you are given after the free survey is the price you pay.
Why the naming causes real problems
An air conditioner and an air-to-water heat pump are the same machine in principle: a refrigerant circuit that moves heat from a cold place to a warm one, running in either direction. Calling one of them an air conditioner and the other a heat pump is a marketing convention, not a technical distinction.
The practical harm is that people who wanted cooling get quoted for an air-to-water system that cannot cool, and people who wanted to get off gas get quoted for air conditioning that cannot heat their hot water. Both quotes are for real equipment and neither does what was asked.
So the useful first question is never which technology. It is: do you want cooling, do you want to replace the boiler, or both.
The grant, and what each system is actually worth
The Boiler Upgrade Scheme pays 7,500 pounds towards an air source heat pump that replaces an existing heating system with one that takes over the heating and the hot water. That is the figure most people mean when they say the heat pump grant.
Since 2026 the same scheme also lists 2,500 pounds towards an air-to-air heat pump, which is an air conditioner. This page said the opposite until 6 September 2026 and it was wrong. Since 2026 the Boiler Upgrade Scheme also lists 2,500 pounds towards an air-to-air heat pump, which is what an air conditioner is. It is not the same as the 7,500 pound grant for an air-to-water heat pump and the conditions are narrower: it depends on what is being replaced, on the property having a valid EPC, and on an MCS certified installation. We will check whether your property qualifies and tell you either way, and we will not put a grant in a quotation until it is confirmed. The current rules are on GOV.UK.
Air-to-water installations also carry 0 percent VAT, where air conditioning is charged at 20 percent. Between the grant and the VAT that is a substantial difference, and it is the reason a heat pump quote and an air conditioning quote are not comparable on headline price.
The heat pump side of this is work we do as well. There is a full explanation on the heat pump page.
The systems that do both, which is what most people actually want
Several manufacturers now run air-to-air and air-to-water off one outdoor unit, so a single machine outside can cool the bedrooms in July, heat them in October, and run the radiators and the hot water all winter.
That removes the choice this page is about, and it removes a second outdoor unit and a second set of consents. It costs more than air conditioning alone and less than buying both systems separately.
It is not right for every property, because it needs the heat loss to suit and enough outdoor capacity, but where it fits it is usually the best answer available. There is more on the heat pump page.
Other things people weigh up
Split vs portable air conditioning
A portable unit costs 300 pounds and a fitted split costs 1,750.
CompareSingle split vs multi-split
If you want more than one room cooled, this is the decision that shapes the whole installation: several small outdoor units, or one bigger one serving all of them.
CompareWhat happens on a survey
An hour, nothing to sign, and a written fixed price afterwards. The fastest way to settle any of this properly.
Free surveyQuestions people ask
Can an air source heat pump cool the house?
An air-to-water heat pump, which is what people normally mean, does not cool in a typical UK installation. It heats water for radiators and hot water.
An air-to-air heat pump, which is what an air conditioner is, both heats and cools. If cooling matters to you, that is the one you want, and it is worth saying so early because the two get quoted interchangeably.
Is air conditioning eligible for a grant?
Not for the 7,500 pound one. That is for an air-to-water heat pump taking over the heating and the hot water. Air conditioning is also still charged at 20 per cent VAT where an air-to-water installation is zero rated.
But it is no longer true that air conditioning gets nothing. Since 2026 the Boiler Upgrade Scheme also lists 2,500 pounds towards an air-to-air heat pump, which is what an air conditioner is. It is not the same as the 7,500 pound grant for an air-to-water heat pump and the conditions are narrower: it depends on what is being replaced, on the property having a valid EPC, and on an MCS certified installation. We will check whether your property qualifies and tell you either way, and we will not put a grant in a quotation until it is confirmed. The current rules are on GOV.UK.
Is air conditioning cheap to heat with?
Yes, and it is the most underused thing about it. A modern unit in heating mode delivers roughly three to four units of heat for every unit of electricity, which makes it far cheaper than any electric heater and competitive with gas for heating one room.
For a loft conversion, a conservatory or a home office the central heating serves badly, heating that one room with the air conditioner is usually cheaper than raising the temperature of the whole house.
Can I have both?
Yes, and increasingly from one outdoor unit. Systems that run air-to-air and air-to-water together will cool the bedrooms in summer and run the radiators and hot water in winter, from a single machine outside.
It suits some properties and not others, and the heat loss survey decides. See the heat pump page.
Not sure which way to go?
Tell us the rooms and what you are trying to achieve. We will say which of these we would fit in your property and why, before anybody quotes anything.
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