What Is The Best Air Source Heat Pump?

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Best air source heat pumps

Are you in the market for a heat pump and wondering what the best option is? In truth, there really isn’t a proper answer to this, only to say that the best air source heat pump is the one that is most suitable for your own requirements. 

Air source heat pumps contain different heat pump technology and can be rated on a number of different features and capacities, and it is which of these factors that you value the most that will help decide the best air source heat pump for you. A look at some of these factors will help you understand which new heat pump may be the most suitable option for you…

Your existing heating set up

Unless you are completely gutting your own property and installing an entirely new heating system, perhaps in place of an old gas boiler, you will need to take into account your existing heating set up so that it is compatible with your chosen heat pump.

If your property currently operates underfloor heating (or low temperature radiators) then low-temperature heat pumps will be more suitable. Alternatively, if you have a more traditional central heating system with standard or oversized radiators, high temperature heat pumps would usually be the right choice.  

That said, it may be possible that a ground source heat pump, or even water source heat pumps (if you are located near to a suitable water source), are a suitable alternative, so they should not be overlooked as a heat pump option. However, the need for available space for the ground loops that need to be excavated to extract heat from the ground, plus the cost, can put ground source heat pumps out of reach for many households.

Existing heating set up

Monobloc or split system

If you want your air source heat pump all packaged in one compact convenient easy to install and maintain package, then a monobloc heat pump should be your preferred option. Consisting of a single outdoor unit, they are a good option when you need to save indoor space, as long as you have got the space outside to house it.

Split system models consist of more than one unit, with a condenser collecting the heat outdoors and transferring this to an indoor unit inside the home where water is heated to serve the heating system. Some split systems come with an integrated hot water storage tank, whereas a monobloc system will require  a separate tank in order to provide hot running water. Find out more about the differences of monobloc v split system air source heat pumps. 

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Heat pump output

The output of an air source heat pump is measured in kilowatts (kW), and generally the larger your home, the greater sized air source heat pump you’ll need. Though other factors can influence this, such as the level of insulation in your property and the degree of seasonal fluctuations in temperatures, here are some rough estimates which may help give you an indication of potential heat pump output requirements:

Property type (based on one with good insulation)Suggested ASHP output required
1-bed flat/apartment2-3kW
2-bed terrace4-5kW
3-bed semi-detached 6-8kW
4-bedroom detached9-11kW
5-bedroom detached 12-16kW
Suggested air source heat pumps

If you are still unsure what size heat pump you need, get in touch with Heat Pumps UK for advice or check out our heat pump size guide.

Desired room temperature

Some people just need their home to be oh so toasty, whether for reasons of comfort or even matters of health. Personal preference will dictate the room temperature you require in your home and therefore from your heat pump.

Around 20°C – 22°C is usually the desired temperature, but if you require your home to be warmer, a larger air source heat pump will be required, while a cooler required room temperature means you could get away with a small sized heat pump.

Heat pump cost

While heat pumps can be a cost-effective way of heating the home, the initial cost can sometimes put people off having them installed. This means that for many, the best air source heat pump will be the one that matches their budget.

Prices for the most basic domestic air source heat pumps start from around £5,000, including the installation, but the larger the output required and the more complex the installation, the greater the costs. If you are unable to hook up your existing heating system (whether using the radiators or underfloor heating elements), this will add to your costs. Find out more about air source heat pumps costs.

Costs of running your system

While the cost of your air source heat pump may be your primary concern, the costs of actually running it will also determine which one you might choose. The efficiency of your heat pump determines how much electricity your unit requires to generate the heat you need.

A good air source heat pump will have an efficiency level of around 300% – meaning for every 1kW of electricity used, around 3kWh of usable heat energy will be produced. Some of the better brands and models can produce efficiencies far in excess of this, sometimes as much as 600%. 

Aside from system efficiency, the cost of running your heat pump will depend on many other factors including the outside temperature, energy expenditure, and how well your home is insulated. Discover more about heat pump running costs.


With efficiency levels far in excess of standard home boilers, an air source heat pump is going to save you money, effectively meaning that the costs of your heat pump will be covered in the long-term by the savings. You will need to weigh up cost versus savings to see which air source heat pump will prove the most cost effective.

Some households may be able to benefit from free grants for solar panels which will reduce the upfront cost of their installation and therefore mean that savings will cover any outlay in a much quicker timescale. 

Environmental impact 

For some people, costs and savings are not the only consideration when it comes to choosing an air source heat pump. Being far more energy efficient, a heat pump will reduce your carbon footprint, and this is a reason for many to embrace this sort of technology in the home.

However, this is not to say that there aren’t other environmental considerations to take into account when it comes to heat pumps. Much like a home refrigerator, an air source heat pump relies on refrigerant gases to work, but these gases can have a negative impact on the environment if there is a leak. 

Refrigerants have their potential environmental impact as a greenhouse gas measured in terms of their global warming potential (GWP) – CO2 has a GWP of 1. Some air source heat pumps can have a low GWP of around 148, while others may have a GWP far in excess of this, so this may be a consideration when choosing the best air source heat pump for you.

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Heat pump noise levels

Air source heat pumps are not noise-free so you may need to consider the noise levels depending on the type of system you choose and the proximity of the unit to your home. Split system models are usually quieter in operation so may be a better option if noise is going to be a consideration.

Some heat pumps can produce noise levels which might be considered louder than some air conditioning units, so you need to weigh up which air source heat pump unit is going to operate with a noise level that you (and potentially your neighbours) are able to tolerate. Discover more about how noisy heat pumps are.

Heat Pump Noise Levels

Brand & years established

Brand names do make a difference. If you are new to air source heat pumps then you may be more familiar with names like Hitachi or Samsung rather than Vaillant or Daikin. This does not mean that these other lesser well known (to you at least) brands are any less well established. 

When choosing by brand, you may want to pay attention to their numbers of years in the heat pump market. The longer a company has been operating in this product area, the more time they have had to encounter errors and problems, thus having had more time to fix them and optimise their products.

While you don’t expect things to go wrong with a new air source heat pump, you want that peace of mind that you are covered in the event of unexpected issues. Most heat pumps come with warranties from the manufacturers of at least 5 years, with extended warranties often also available.

Heat Pump Options

With a range of top brands, the choice of air source heat pump can be somewhat overwhelming. Here we select a few of the best air source heat pump brand options that may be suitable, depending on your requirements.

LG Air Source Heat Pump

LG heat pump

While known for their range of home electronic goods and appliances, the South Korean manufacturer has been carving itself out a position in the manufacture of renewable energy systems, including heat pumps, since 2007. Their heat pump range offers a variety of options to suit different property sizes and budgets, including more compact monobloc unit systems, split heat pump systems and hydrosplit heat pumps.

It’s possible that you’ll find the best air source heat pump for you here, simply because LG are a leading manufacturer of air source heat pumps, and have a range of products suitable for different homes. Many of them come with a lengthy warranty of 7 years, too, meaning you can be confident in their durability.

Find out more about LG’s range of air source heat pumps below:

LG Split heat pumpsMonobloc heat pumps
InstallationFlexible installationSingle compact unit
Common modelsR32 Split 4/ kW Hydro, R32 Split 5/7/9 kW Hydro Box, R410A Split Hydro Box & High TemperatureR32 Monobloc S, R32 Monobloc S (2Fan)
Energy classA+++ (average climate at 35℃ water outlet)A+++ (average climate at 35℃ water outlet)
Leaving water temperatureup to 65 ℃ for R32 / 5,7,9kW models / 57 ℃ for R410A models / 55 ℃ for R32 4,6kW models / 80℃ for High temperature modelUp to 65 ℃
Minimum outdoor temperature As low as -25 ℃ for R32 5,7,9kW, R410A and High Temperature models / -20 ℃ for R32 4,6kW modelsAs low as -25 ℃
Unit typeWall-mounted hydro box or floor-standing integrated water tank type indoor unitNo indoor space for indoor unit needed

LG Heat Pump general features

  • Are highly efficient and can reduce energy bills significantly.
  • The units operate quietly, making them ideal for residential use.
  • Use the low GWP refrigerant R32, meaning they have a reduced carbon footprint compared to other heat pumps on the market.
  • Seven year warranty provides full peace of mind.
  • The units utilise LG’s own R1 scroll compressor, making them very reliable and efficient.

View our more extensive LG heat pump review

Daikin Air Source Heat Pumps

Daikin heat pump

Daikin made its mark as a world-leading air conditioning unit company, but since 2009 has been selling residential heat pumps. As a Japanese company, their reputation as an innovative quality manufacturer makes them a brand you can trust. While their Altherma product range can be somewhat more expensive than other manufacturers, the quality of engineering makes them a price that many feel is worth paying.

Perhaps the main appeal of any Daikin air source heat pump is their modern, Japanese design, allowing them to fit seamlessly with any home. Perhaps the best air source heat pump for your home is one that matches your modern design. But their ability to operate in cold temperatures make them more than just a stylish option – they’re incredibly practical too for most UK homes. 

Find out more about the Daikin air source heat pump range below:

Altherma low-temperature heat pumpsAltherma mid-temperature heat pumpsAltherma high-temperature heat pumps
InstallationClever build means simple installationSmart design simplifies installation, maintenance and service
Smart build simplifies installation
Common modelsAltherma 3 R F, Altherma 3 R W, Altherma 3 M,Altherma 3 H MT F, Altherma 3 H MT WAltherma 3 H HT F, Altherma 3 H HT W
Energy classA+++A+++A+++
Leaving water temperatureup to 60 ℃ Up to 65 ℃Up to 65 ℃
Minimum outdoor temperature As low as -25 ℃ As low as -28 ℃As low as -28 ℃
Unit typeA sleek and modern design that blends into your interior
Perfect solution to boiler replacements and can connect to domestic hot water tank or thermal store
Designed to be a heating system replacement in older homes

Daikin heat pump general features

  • Can operate in extremely cold temperatures
  • Modern, stylish design
  • Can connect to existing radiators
  • Save on electricity bills
  • Can provide maximum flow temperature up to 70℃
  • Despite higher price, they could pay for themselves in as little as 5 years
  • Low maintenance due to high quality parts 

View our more extensive Daikin heat pump review

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Vaillant Air Source Heat Pump

vaillant logo

A well-known boiler brand in the UK, Vaillant have branched into heat pumps with great success and offer a reliable solution for those looking to upgrade their heating system. With most of their products having been awarded the ‘Quiet Mark’ this marks them out as a low-decibel heat pump unit perfect for domestic use. The aroTHERM line is Vaillant’s air-to-water heat pump main range although they do also offer aroTHERM hybrid beat pump systems which enables properties to operate their heat pump system alongside existing heating, such as a boiler, so that the most efficient generator is selected at the right time.

The best thing about the aroTHERM air source heat pump is that it is so compatible with UK heating systems, making it an easy option for many UK homeowners. Many consider a Vaillant air source heat pump to be the best air source heat pump simply because its installation is so seamless. But there are a range of other benefits to them, too. 

Read more about the aroTHERM air source heat pump:

aroTHERM air source heat pump
InstallationCompact size for easy fitting
Common models15kW,11kW,8kW, 5kW, 
Energy classA+++
Leaving water temperatureUp to 63 ℃
Minimum outdoor temperature -15 ℃  (5kW), -20 ℃ (8kW, 11kW, 15kW)
Unit typeSolid case design with in-built vandalism measure

Vaillant heat pump general features

  • Can easily be integrated into UK heating systems
  • Certified by the by the Microgeneration Certification Scheme (MCS)
  • Warranties from 5-7 years
  • ‘Quiet Mark’ approved for quiet operation thanks to their low decibel operation sound
  • Critical components of their design are specifically manufactured with preventing corrosion in mind – important in rainy UK weather

Mitsubishi Air Source Heat Pumps

mitsubishi logo

The long-standing Japanese company has an exceptional Ecodan heat pump range, which has been sold commercially since 2007. Its award-winning Ecodan range is made, according to the company, specifically with the UK climate in mind. While its range can be somewhat pricier than some of its competitors, it’s the quality and reliability from a trusted brand that marks it out as one of the best air source heat pump options available.

As a tried and tested brand, you might expect Mitsubishi to be widely accepted as the best air source heat pump manufacturer, but the competition is certainly stiff. With that said, Mitsubishi’s air source heat pump range shines thanks to the high quality products they produce. The Ecodan range is award-winning for a reason, and it’s thanks to their premium performance and outstanding reliability, and their easy connectivity to most UK boilers for those looking to keep a backup power source in place. Essentially, a Mitsubishi Ecodan heat pump offers the best of both worlds. 

You can read more about the Mitsubishi Ecodan heat pump below:

Ecodan Monobloc heat pumps
InstallationSingle compact unit requiring minimal space
Common modelsR744 QUHZ-W40VA,  R32 Ultra Quiet PUZ, R32 Compact PUZ,R32 Zubadan PUZ, Coastal Protection Models
Energy classA+++ 
Leaving water temperatureUp to 60 ℃
Minimum outdoor temperature As low as -15 ℃ (R744),  -20 ℃ (R32 Compact), -28 ℃ (R32 Zubadan)
Unit typeSelf-contained unit to be placed outside the property

Mitsubishi Ecodan general features

  • Superior technology with reliable performance 
  • Can easily be connected with an existing boiler to provide backup option
  • Deploy an inverter in their units to keep rooms at optimum temperature
  • Ultra quiet models eliminates need for planning permission
  • 5 year warranty as standard
  • Control unit can be synched to an app on your phone

What Is The Best Air Source Heat Pump: Summary

The different air source heat pumps we’ve covered throughout our post all shine in different areas and are from leading brands in the heat pump industry. Whether it’s their brand name and reputation, stylish design, or superior technology – each one stands up on its own. And the question isn’t really ‘what is the best air source heat pump’, but instead ‘what is the best air source heat pump for me‘. 

Ideally you want an energy efficient heat pump that is able to generate renewable energy from the outside air, whether that is to produce heat, hot water, or both. Improved energy efficiency will have a positive impact on energy bills and help you potentially upgrade from a traditional gas boiler, or existing heating systems, to an option with much lower running costs.

Hopefully, our guide today will help you make your mind up regarding the best heat pumps. Approach the decision with your requirements in mind and then take a look at the options that are open to you and decide which one matches your needs the best. 

Made your mind up? Want a quote for an air source heat pump? Then contact Heat Pumps UK today for a price for a new heat pump installation at your property, or see if we can help you access available government grants of up to £7,500 under the Boiler Upgrade Scheme. Make the first move today to reduce your energy consumption, save money, and reduce your carbon emissions.

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Ollie Creevy
Ollie has been writing content online about home improvements for over 3 years. With a real interest and in-depth knowledge of heat pumps and ECO home improvement measures you can use to save on your energy bills. Ollie also keeps up to date with all the Government grants available for you to take advantage of like ECO4 and the Boiler Upgrade Scheme.