- The best all-round air source heat pump is the Aira Heat Pump 12kW
- A heat pump could cut your home’s carbon footprint by up to 65%
- We spent 29 hours reviewing air source heat pumps on the UK market
- Compared across five key criteria, including efficiency, warranty and weight
- Find the right heat pump for your home with our pick of the best
Air source heat pumps extract heat from the air outside and compress it to deliver warm air and hot water for your home.
By replacing your boiler with an air source heat pump (ASHP), you could slash your home’s carbon footprint by up to 65%.
That said, making the transition from a traditional gas boiler to a heat pump is not cheap. The average UK ASHP installation cost £12,600 so far this year – according to the MCS.
The good news is, government grants for heat pumps currently cover a decent chunk of that cost, with £7,500 available to households under the Boiler Upgrade Scheme.
This means that replacing your gas boiler with a heat pump is now comparable in cost (to you), as replacing it with a like-for-like gas boiler would be.
What’s more, with gas slowly being phased out of our energy mix, it’s a good idea to make the switch now, while the government is still willing to pick up the lion’s share of the bill.
How we chose the best air source heat pumps
While all air source heat pumps work in much the same way, but there’s a surprising range of brands and sizes on the market these days. Choose wisely, and your heat pump will provide clean, green heating and hot water for years to come.
With that in mind, it’s important to choose the right ASHP to suit your home, your energy needs and your budget – and we’re here to help you do that.
Our team of experts analysed 22 of the top air source heat pumps available in the UK from 19 manufacturers and selected the best, based on key criteria, including:
- Efficiency
- Warranty
- Power
- Range of sizes available
- Cold weather performance
- Compactness
- Aesthetics
- Value for money
Take a look at our picks, and find out which heat pump could be right for your home before getting a quote from a trusted installer.
The best air source heat pumps at a glance
Here’s a handy comparison chart with the key specs of our top nine best heat pumps:
| Air source heat pump model | Typical price | Size (W/H/D) | Efficiency | Warranty | Best for |
|---|---|---|---|---|---|
| Aira Heat Pump | From £3,000 | 1,152 x 1,503 x 416mm | 470% | 15 years | All round |
| Grant Aerona³ R32 17kW | £5,142 | 1,024 x 1,418 x 403mm | 479% | 7 years* | Larger homes |
| Dimplex System H6 HTi70 8kW | POA | 1,035 x 1,075 x 450mm | 572% | 2 years | Efficiency |
| LG Therma V R32 Monobloc 16kW | £4,550 | 1,239 x 1,380 x 330mm | 400% | 7 years* | Quiet operation |
| Vaillant flexoTHERM 400v 19kW | £8,229 | 600 x 1,183 x 595mm | 467% | 7 years* | Power |
| Samsung EHS Mono R32 16kW | £3,223 | 940 x 1,420 x 330mm | 442% | 3 years* | On a budget |
| MasterTherm UK BoxAir Inverter A7W35 | POA | 1,300 x 1,495 x 526mm | 520% | 7 years | Durability |
| Daikin Altherma 3 H HT 14kW | £4,838 | 595 x 1,650 x 625mm | 451% | 5 years* | Cold weather |
| HydroPro P12 | £1,502 | 390 x 600 x 100mm | 480% | 2 years | Swimming pools |
Find out how much a heat pump would cost for your home with our quick quote tool, and our trusted heat pump installers will be in touch. Also check out our article on heat pump costs, so that you know what to expect when discussing quotes.
Aira Heat Pump 12kW – best all-rounder
Engineers at Swedish firm Aira have over 20 years of experience working with heat pumps, but the company has only now arrived in the UK to shake up the heat pumps market, and it means business.
Aira’s 15-year ‘Comfort Guarantee’ – a whopping five years longer than its closest rival – includes performance, product and installation warranties for full peace of mind.
Thanks to a subscription-style plan that includes a smart monitoring app and maintenance, you don’t have to pay for the heat pump upfront. Aira’s engineers can even fix your system remotely via the app.
The pump’s sleek black outdoor unit lives up to its good looks with solid performance ratings, including one of the best freezing weather operation scores in our test.
| Model featured | 12kW | Min temp | -25 °C |
| Typical price (this model) | From £3,000 | Energy rating | A++ to A+++ |
| Dimensions (W/H/D) | 1,152 x 1,503 x 416 mm | Models available | 6, 8, 12kW |
| Efficiency | 470% | Warranty (years) | 15 |
- 15-year warranty beats all competitors by years
- Sleek black outdoor unit looks superb
- Efficiency and cold weather ratings are excellent
- Companion app lets you control thermostat, access features and troubleshoot
- Biggest model is 12kW, which may be too small for larger homes
Grant Aerona³ R32 17kW – best for larger homes
The powerful 17 kW model of the Grant Aerona³ R32 offers a superb balance of performance, compactness and value for money. At 120 kg and just over £6,000, this relatively unobtrusive heat pump is powerful enough to provide heating and hot water for a detached house.
If 17 kW exceeds your needs and budget, you can get the Aerona³ R32 in a wide range of smaller sizes. The 6 kW model measures less than 40 cm by 90 cm, weighs just 51 kg and costs around just £2,800.
Whichever size you go for, the Grant heat pump delivers above-average efficiency, even when it’s -20°C outdoors, and comes with a seven-year warranty.
| Model featured | 17kW | Min temp | -20 °C |
| Typical price (this model) | £5,142 | Energy rating | A++ to A+++ |
| Dimensions (W/H/D) | 1,024 x 1,418 x 403 mm | Models available | 6, 10, 13, 17kW |
| Efficiency | 479% | Warranty (years) | 7 (approved installer) |
- One of the best value for money heat pumps in our test
- Peak efficiency of 479% is well above average
- Surprisingly small and light for such a powerful heat pump
- Seven-year warranty is good, but requires approved installation
- Looks more utilitarian than some rivals
Vaillant aroTHERM Plus 7kW – best for future-proofing
The aroTHERM Plus uses what Vaillant calls the “most cutting-edge” heat pump technology on the market, with natural refrigerant that frees you from dependency on any conventional fuels – especially if you use solar panels to power the pump. This makes it one of the most eco-friendly and future-proof products in our rundown.
Vaillant is renowned for its premium boilers, so you may be surprised to hear that you can buy a 7kW model of the company’s aroTHERM Plus air-source heat pump for just over £4,000, cheaper than some rivals.
As with many heat pumps you’ll also want to buy a water cylinder and indoor unit, and Vaillant requires that you pay for an approved installer to get the full seven-year warranty. Even so, we think this impressive machine is very good value, and at 7kW our featured model is big enough to heat a three-bedroom house.
All sizes of the aroTHERM Plus have a good seven-year warranty, provided you use an approved installer, and they all boast an excellent efficiency rating that sees them produce around five times the energy they use.
| Model featured | 7kW | Min temp | -20 °C |
| Typical price (this model) | £6,091 | Energy rating | A++ to A+++ |
| Dimensions (W/H/D) | 1,100 x 765 x 449 mm | Models available | 3.5, 5, 7, 12kW |
| Efficiency | 503% | Warranty (years) | 7 (approved installer) |
- Uses natural refrigerant that's more future-proof and eco-friendly than conventional alternatives
- All models have outstanding energy and efficiency ratings
- Can quickly heat water to 65°C as well as heating a house
- Seven-year product warranty is at the top end of the market
- Most powerful model is 12kW, smaller than some competitors – but its high efficiency rating helps to compensate
LG Therma V R32 Monobloc S 16kW – best value
The LG Therma heat pump’s noise reduction technology makes it a fine choice for flats and other urban homes. Its lack of external refrigerant piping makes it easy to install, so it’s effectively a plug-and-play device.
The Monobloc S, which comes in an unusually wide range of six sizes from 5kW to 16kW, is also a great fit for cold climates. It works in temperatures as low as -25, and performs at 100% of its capacity when it’s as cold as -10°C out.
All this convenience comes at a relatively low price, with the most powerful 16kW model costing a typical £4,550 including VAT. That’s around the same as you’d pay for significantly smaller models of many rival heat pumps.
| Model featured | 16kW | Min temp | -25 °C |
| Typical price (this model) | £4,550 | Energy rating | A++ to A+++ |
| Dimensions (W/H/D) | 1,239 x 1,380 x 330 mm | Models available | 5, 7, 9, 12, 14, 16kW |
| Efficiency | 400% | Warranty (years) | 7 (approved installer) |
- Great price for one of our top all-round heat pumps
- Works at -25°C, which is much better than industry average
- Seven-year warranty is among the best
- Uses environmentally-friendly R32 refrigerant
- Simple installation and quiet operation make it a convenient choice
- Efficiency of 400% is at the bottom end of our top nine pumps
Vaillant flexoTHERM 400v 19kW – best for power
The flexoTHERM heat pump from boiler specialist Vaillant is one of very few pumps to be available in a 19 kW model, which is powerful enough to heat and provide hot water for a large detached house.
This impressive machine, which can quickly heat water to 65°C, is also available in smaller, cheaper models from 5 kW upwards.
All sizes of the flexoTHERM have an excellent seven-year warranty and a good efficiency rating that sees them produce nearly five times the energy they use.
| Model featured | 19kW | Min temp | -10 °C |
| Typical price (this model) | £8,229 | Energy rating | A++ to A+++ |
| Dimensions (W/H/D) | 600 x 1,183 x 595 mm | Models available | 5, 8, 11, 15, 19kW |
| Efficiency | 467% | Warranty (years) | 7 (approved installer) |
- Huge range of sizes available, from 5 kW up to 19 kW
- Above average efficiency rating in all sizes
- Very compact for such a powerful heat pump
- Excellent seven-year product warranty
- The 19 kW model is expensive, costing over £8,000
Samsung EHS Mono HT Quiet – best quiet
Samsung’s sleek new heat pump excels on many fronts. It’s got one of the best efficiency ratings we came across, its cold weather operation is excellent, and it can produce water as hot as 70°C – just what you need for those steamy showers and baths in the depths of winter. Unlike many older heat pumps, the HT Quiet could replace your gas boiler altogether.
What impresses us most, however, is the lack of noise from this handsome dark grey unit. Older heat pumps and air conditioners can be decidedly audible devices to live with, but the EHS Mono HT Quiet uses new-generation noise-reducing technologies to operate at levels as low as 35 decibels, which is quieter than most fridges.
Given all these advantages, we were pleased to find that the mid-range 12kW model of Sasmung’s heat pump has a typical retail price tag of just over £4,000 including VAT, which makes it one of the best buys on our list.
| Model featured | 12kW | Min temp | -25 °C |
| Typical price (this model) | £4,060 | Energy rating | A+++ |
| Dimensions (W/H/D) | 1270 x 1018 x 530 mm | Models available | 8, 12, 14kW |
| Efficiency | 500% | Warranty (years) | 7 |
- Runs as quietly as 35dB, which falls somewhere between a whisper and a fridge!
- Outstanding hot water levels, so it can potentially replace your boiler for good
- Excellent performance in low temperatures
- Dark grey unit looks stylish and modern
- Uses environmentally-friendly R32 refrigerant
- Largest model in this range is 14kW, which is less powerful than some rivals in our rundown
MasterTherm UK BoxAir Inverter – best for durability
MasterTherm’s heat pump is at the premium end of the market. Unlike conventional heat pumps, it contains an inverter that ensures consistent temperatures without the unit having to keep stopping and starting. The result is a supremely durable device that should last much longer than its seven-year warranty guarantees.
The MasterTherm is available in a range of sizes, but each size covers a range of power ratings. This gives you more freedom over which unit to choose. In our research we focused on the 5-13 kW model, which is powerful enough for most homes.
| Model featured | 5-13kW | Min temp | -20 °C |
| Typical price (this model) | POA | Energy rating | A++ to A+++ |
| Dimensions (W/H/D) | 1,300 x 1,495 x 526 mm | Models available | 2-7, 3-9, 5-13, 5-17, 7-22 kW |
| Efficiency | 520% | Warranty (years) | 7 |
- Excellent seven-year warranty with no strings
- Based on inverter technology that delivers reliable, consistent heat
- Outstanding 520% efficiency
- Internet connected, with app for control and troubleshooting
- Potentially very expensive, with kit versions costing £16,000 or more
Daikin Altherma 3 H HT – best for hot water in cold weather
Daikin’s sleek black heat pump excels in two compatible areas: providing piping hot water, and working in very low temperatures. So if you’re forever craving hot baths in winter, this is the heat pump for you.
The Altherma 3 H HT, which comes in sizes from 8 kW to 18 kW, can supply water at temperatures up to 70°C – the same as gas boilers – and can do so when it’s a bitter -15°C outside.
Like all heat pumps, the Daikin doesn’t produce quite as much heat when the mercury drops even lower. But it still works at -28°C, which no other heat pump can match.
| Model featured | 14kW | Min temp | -28 °C |
| Typical price (this model) | £4,838 | Energy rating | A++ to A+++ |
| Dimensions (W/H/D) | 595 x 1,650 x 625 mm | Models available | 14, 16, 18kW |
| Efficiency | 451% | Warranty (years) | 5 (approved installer) |
- Simpler to install than many machines
- Supplies water at 70 °C – the same as gas boilers
- No need for new radiators or insulation
- Outstanding minimum operating temperature of -28°C
- Only a five-year warranty with an approved installer
HydroPro ECO 12 – best for swimming pools
If you’re lucky enough to have a pool out the back, heating it will be one of your biggest uses of energy. To cut your bill and carbon footprint, invest in a heat pump to do the job.
We chose the 12kW P12 because it’s significantly cheaper than most swimming pool heat pumps, costing around £1,550 plus installation – around half the price of most similar products.
| Model featured | 12kW | Min temp | 11 °C (water temp) |
| Typical price (this model) | £1,502 | Energy rating | Info not available |
| Dimensions (W/H/D) | 390 x 600 x 100 mm | Models available | 6kW – 26kW |
| Efficiency | 480% | Warranty (years) | 2 |
- Costs much less than most swimming pool heat pumps
- Efficient, producing nearly five times the energy it uses
- Very compact and light pump won't take up much garden space
- Available in a wide range of sizes from 6kW to an amazing 26kW
- For swimming pools only
- Two-year warranty is the lowest in our test
Key criteria explained
Our research team scrutinised the pros, cons and specifications of dozens of leading air source heat pumps. Then we chose our top nine according to key factors including value for money, efficiency, product warranty and minimum operating temperature.
Here’s why these factors matter:
Efficiency
A heat pump’s efficiency rating refers to the amount of energy (heat) it generates, versus the energy (electricity) it uses to run. The average pump is 300%-400% efficiency, but we found models that far exceed this. All our top nine have efficiency ratings of above 400%.
Warranty
Five years is the average product warranty for heat pumps, but most of our top nine are guaranteed to last and perform for longer than this. Our best air source heat pump overall, the Aira Heat Pump, has a whopping 15-year product and performance warranty.
Power and range
The bigger your house, the more powerful your heat pump needs to be. Most of the products we recommend are available in a range of sizes, from 5 kW (ideal for a flat) all the way up to 19 kW, which can heat a large household. Our favourite heat pumps come in a wide range of models, from low power to high power.
Cold weather performance
Air source heat pumps can extract latent heat from the air even when it’s freezing outside. The best heat pumps have a minimum operating temperature of -20°C or colder. We rarely experience those temperatures in the UK, but a broad operating temperature is a good indication of a heat pump’s quality.
Compactness
A typical 14 kW heat pump unit measures a metre or two across and weighs up to around 250 kg. That’s a lot of space on a balcony or in a small garden, so we’ve prioritised smaller, lighter heat pumps that don’t scrimp on power or efficiency.
Aesthetics
A heat pump is a large device positioned against an outdoor wall of your home, so it is quite visible. As with the best solar panels, older and cheaper heat pumps have a utilitarian look, while newer models have a dark, sleek appearance that will soon have your neighbours asking where you bought yours.
Value for money
The UK Boiler Upgrade Scheme covers up to £7,500 of the cost of buying and installing a heat pump (see Next steps below). The best heat pump installers will apply on your behalf for the grant, which rises to £9,000 in Scottish rural areas.
So don’t just go for the cheapest heat pump you can find. Instead, look for great value for money. The models that rank highest in our rundown deliver the best performance, features and lifespan for their price.
How to access the Boiler Upgrade Scheme
Through the Boiler Upgrade Scheme, homeowners can receive up to £7,500 off the upfront cost of a heat pump or biomass boiler.
To be eligible, you need to meet the following requirements:
- You need to own the property you’re applying for, including if it’s a business, a second home, or a property you rent out to tenants.
- You must be replacing a fossil fuel heating system, such as oil, gas, electric or LPG (liquefied petroleum gas)
- You’ve got to have a valid Energy Performance Rating (EPC), which is valid for 10 years
You’re also still eligible if you’ve already had funding to make your property energy efficient. Your installer also must commission and install the heat pump within 120 days of applying for the grant or it won’t be eligible.
There are also some properties that won’t be able to receive a grant for. These include:
- Most new build properties. If you move into a finished new build with a fossil fuel boiler, however, you may be able to get a grant for a heat pump under the scheme.
- Social housing
- A property that’s already been given government funding or support for a heat pump or biomass boiler
If you own a self-build property, it’s eligible for the grant if:
- You or the original owner built it yourself or you paid a builder to build it
- It’s never been owned by a business or organisation
- You canshow you installer proof that your property is a self-build.
The first step to applying is contacting MCS certified installers to get quotes. Your installer will be able to tell you if you’re eligible and they will apply on your behalf on the Ofgem website. The value of the grant will be taken off the amount you pay for installation.
Next steps
If you like the idea of switching to clean heating but don’t fancy paying several thousand pounds for a heat pump, we have good news. The government will pay a large chunk of it for you.
The UK Boiler Upgrade Scheme (BUS), which applies to England and Wales, knocks £7,500 off the price of an air source heat pump and installation.
To get your funding, first obtain around three quotes from professional installers.
Fill in our quick quote tool and we’ll put you in touch with our trusted MCS-certified heat pump installers.
Once you agree a quote with your installer, the value of the grant from the BUS will be deducted from the quote.
In Scotland, Home Energy Scotland offers a £7,500 grant for air source heat pumps, or £9,000 in rural areas, plus an additional loan up to £7,500.
