Best ASHPs

When it comes to choosing the best air source heat pump for your home, it can feel overwhelming as there are a lot of factors to consider. Don’t worry – I’m here to help!

In this blog post, I take a look at some of the best air source heat pumps on the market in 2022.

These pumps have come a long way in recent years and are now one of the best, environmentally intelligent options for heating your home. And are recommended in The Best Alternatives to Gas Boilers article.

When it comes to recommendations, I consider cost, installation, reliability, potential home adaptations needed and manufacturer reputation.

Whether you’re looking to replace your current heating system or you’re just starting to research your options, an air source heat pump is definitely worth considering!

Air source heat pump overview

Air Source Heat Pump is a type of renewable energy technology that can be used for both heating and cooling your home.

Heat pumps work by transferring heat from one place to another, and they are very efficient because they use a small amount of electricity to move the heat.

air-source heat pump (air-to-water)
Image credit

Air source heat pumps take ambient heat from the air outside (some models can work in temperatures as low as -25C) using a small amount of electricity to drive a fan. This heat is then compressed, increasing the temperature further, so it can be conducted through a heat exchanger to warm water in a cylinder. This heated water is then used for your taps, radiators or underfloor heating.

There are two types of air-source heat pumps: air-to-air and air-to-water. They use the same method to generate heat, yet they provide it in different ways.

Air-to-air heat pumps utilise a network of fans to distribute the heat and can be used for cooling during the summer months potentially negating the need for separate air conditioning units.

This post is on air-to-water heat pumps.

Air-to-water heat pumps are used to heat water and then distribute warmth via central heating systems (radiators and underfloor heating) and are the subject of this post.

What are the best air-source heat pumps?

1. Best for Heat Output RangeDaikin Altherma 3

Daikin Logo

Paul’s Take:

Daikin, is a Japanese company, with a credible 90-year history of providing climate control technology. With a global reputation, Daikin is an obvious choice and an easy recommendation.

The Daikin Altherma 3 range includes a low-temperature unit (Altherma 3 R) and a high-temperature unit (Altherma 3 H HT) providing options for the majority of domestic needs.

Dakin’s high-temperature heat pumps deliver hot water as high as 75°C, and installing a heat pump unit from this range means they can be used in homes that are less heat efficient and compatible with conventional heating systems infrastructure (your existing radiators are not low-temperature radiators), negating the need for a costly refit. Not to worry, if you happen to have newer radiators or an underfloor heating system, Daikin have you covered with low-temperature models to suit.

Daikin Altherma 3 ASHP

Daikin Altherma 3 H HT air-to-water heat pump delivers heating, cooling and instant hot water.

1. Wall-mounted model – A compact unit that combines with a separate tank to deliver domestic hot water. This model offers an optional cooling function.

2. Integrated DHW stainless steel tank model – A compact unit with a footprint of 595x625mm. The unit connects to a 180 or 230L tank to meet domestic hot water demand and can operate in either a cooling or bi-zone setting.

3. Integrated ECH2O DHW tank model – The ECH2O unit comes with a thermal DHW tank of 300 or 500L that can connect to thermal solar panels. This model offers an optional cooling setting.

Key Features:

  • Can operate when outdoor temperatures are as low as -28°C.
  • High temperature (up to 80°C) and low-temperature options.
  • Split and monobloc units.
  • Solar power compatible (certain units).
  • Integrated hot water storage tanks are available.
  • Low noise units are available.
  • Awarded the EU Ecolabel (high efficiency and low environmental impact).
ModelDaikin Altherma 3
Outputs (kW)4, 6, 8
Lowest Temp-28°C
Max Temp Output75°C
Max Efficiency453%
Noise Level (dBA)62
Warranty5 years
Potential Cost£6,000 – £8,000

2. Best for Value For Money – Grant Aerona3 R32

Grant Logo

Paul’s Take

The MCS approved (eligible for the Boiler Upgrade Scheme) Grant Aerona³, is a highly efficient air-to-water heat pump delivering outstanding performance even when external temperatures are low. The units are reliable and are one of the highest quality, best value for money models on the market today.

With high SCOP (Seasonal Coefficient of Performance) ratings in average climate conditions from 4.54 to 5.4. This means on average, the units produce 4.9 units of heat for every unit of electricity used.

Grant, a UK based company, has been manufacturing heating products for four decades, having established itself as a reputable producer of oil-fired condensing boilers moved into renewable products in 2010 with the launch of the Grant Aerona, their first-generation air-to-water heat pump. In 2016, Grant launched their third-generation (Aerona³) inverter-driven ASHP.

The Grant Aerona³ range is available in four single-phase, monobloc units with outputs of 6kW, 10kW, 13kW and 17kW:

ModelDimensions (HxWxD) mmWeightSCOP @35°CNoise
Grant Aerona³ 6kW R32675 x 898 x 379.451kg4.6165dB

Grant Aerona³ 10kW R32
882 x 874 x 40570kg5.2064dB

Grant Aerona³ 13kW R32
1418 x 1024
x 403

Grant Aerona³ 17kW R32
1418 x 1024
x 403

The inverter-driven Aerona³ R32 heat pump works efficiently even when temperatures drop as low as -20°C and operate with low noise levels and both the 13kW and 17kW models have been awarded the Quiet Mark.

All models feature weather compensation controls and the system is compact in size which is ideal for space-limited homes and enables an easier installation. The range is installer-friendly and easy to maintain.

Grant Aerona³ R32 Air Source Outside

Available with a 7-year guarantee (*when installed by a G1 Installer, subject to Terms and Conditions)

Each model operates at incredibly high efficiencies, even when external temperatures are low, making for a cost-effective renewable alternative to traditional off-gas heating methods

Using a simple, user-friendly programmable room stat, the heat pumps are straightforward to control.

All models use the R32 refrigerant with a Global Warming Potential (GWP) of 675 – this is 70% lower than R410A (GWP of 2088).

Key Features:

  • Quiet mark for 13kW and 17kW models
  • Built-in weather compensation
  • Compact footprint
  • ERP rating of A+++ from September 2019
ModelGrant Aerona3 R32
Outputs (kW)6, 10, 13, 17
Lowest Temp-20°C
Max Temp Output45°C
Max Efficiency462%
Noise Level (dBA)61 – 64
Warranty7 years
Potential Cost£7,000 – £7,000

3. Best for Max Temp Output – Hitachi Yutaki S80

Hitachi Logo

Paul’s Take

Hitachi has long been a leader in the consumer electronics sector and, like other well-known heat pump producers, has moved into the increasingly popular home renewable energy sector.

Hitachi’s Yutaki line of air source heat pumps, which includes the S80, is one of the most energy-efficient air source heat pumps. The S80 heat pump converts every kilowatt of electricity into 5kW of heating energy. Compared to traditional boilers, it can reduce electricity bills by up to 60% and CO2 emissions by 50%.

The Hitachi Yutaki heat pump is not only one of the most efficient residential heat pumps on the market, but also one of the highest temperature systems heating water up to 80°C, even with outdoor temperatures as low as -20°C.

Hitachi Yutaki S80 Outdoor Unit

The S80 comes with a wireless control enabling remote adjustments of room temperatures and has a convenient one-touch button to put the unit into holiday mode.

Key Features:

  • ERP rating of A+++
ModelHitachi Yutaki S80
Outputs (kW)11, 14, 16
Lowest Temp-20°C
Max Temp Output80°C
Max Efficiency475%
Noise Level (dBA)63 – 65
Warranty5 years
Potential Cost£4,000 – £7,000

4. Best for … Samsung EHS Monobloc

Samsung Logo

Paul’s Take


ModelSamsung EHS Monobloc
Outputs (kW)5, 9, 12, 14, 16
Lowest Temp-25°C
Max Temp Output65°C
Max Efficiency485%
Noise Level (dBA)61 – 68
Warranty7 years
Potential Cost£4,000 – £

What is an air source heat pump and how does it work?

An air-source heat pump is a heating system that extracts heat from the ambient air outside your home and uses it to warm up the air inside your home.

An air-source heat pump utilises electricity to power a compressor and fans which transfer heat energy from the external air into the building but the heat energy delivered to your home is more than the electrical energy used to power the system.

If well designed, you could expect the heat pump system to deliver three times as much heat energy as is used in electrical energy to drive the system.

The benefits of using an air source heat pump for heating your home

Air source heat pumps provide a number of benefits over traditional fuel-based heating systems.

  • They can be much more efficient than traditional heating systems, meaning that you may save money on your energy bills.
  • Air-source heat pumps are much less reliant on fossil fuels, making them a low carbon heating system.
  • Heat pumps have the added benefit of providing cooling in summer, potentially negating the need for a separate air conditioning unit, making them a versatile option for year-round climate control.
  • They are relatively easy to install compared to other types of heating systems. Heat pumps do not require a lot of expensive or difficult-to-install infrastructure making them a great option for a heating system upgrade.
  • Air-source heat pumps are generally very reliable. These systems have been around for decades, and they have a proven track record of reliability.
  • They are generally cheaper to run than oil boilers and can be cheaper than running gas boilers, especially in the current climate of increased gas costs.

How to choose the best air source heat pump for your needs

When it comes to choosing the best air source heat pump for your needs, there are a few factors you’ll want to take into consideration.

  • Air source heat pumps are generally more expensive than traditional heating systems, so you’ll need to make sure that you can afford the initial investment.
  • Air source heat pumps need to be installed by a qualified technician, so you’ll need to make sure that you’re comfortable with the installation process.
  • Reliability is another key factor to consider. Air source heat pumps are generally very reliable, but it’s always best to check with manufacturers and reviews to make sure that you’re getting a reliable product.
  • Finally, you’ll need to consider the possible need for home adaptations. Air source heat pumps generally don’t require any special adaptations, but it’s always best to check with your installer to make sure that your home (e.g. radiators) is compatible with an air source heat pump.

Cost and installation of air source heat pumps

The cost of an air source heat pump will vary depending on the size and type of system you need, as well as the climate in which you live. In general, however, air-source heat pumps are cost-effective, with some systems paying for themselves in just a few years.

Installation of an air source heat pump is usually straightforward, and while they can often be installed by an experienced DIYer we would recommend hiring a professional installer, especially if you are installing a larger system, or if your home is not well-suited to an air source heat pump.

The cost to install is typically higher than a conventional heating system with costs anywhere between £8 – £20k, typically coming in around £12k.

From April 2022 to March 2025, the government’s Boiler Upgrade Scheme will reduce the cost of air source heat pumps by £5,000.

Further savings will be realised after Rishi Sunak’s Spring Statement announced on the 23rd March 2022:

What are the advantages and disadvantages of an air source heating system?


  • Environmentally friendly – Air source heat pumps are very eco-friendly and leave a far smaller carbon footprint than traditional gas or LPG boilers (more so if you generate the electricity needed from solar panels) allowing you to do your bit for the environment. As well as being more energy-efficient than traditional heating systems they can also be used to cool your home.
  • Cheaper than other green heating systems – compared to other eco-friendly heating systems, such as a ground source heat pump, air source heating systems are much cheaper to buy.
  • Low running costs – An air source heat pump costs much less to run than a gas boiler so your energy bills should be lower. They have low maintenance costs and can be expected to provide safe, reliable and emission-free heating for many years
  • Easy Installation – An air source heat pump can be much simpler to install than other environmentally-friendly heating systems. This means less disruption and lower installation costs too.
  • Eligible for Incentives – Renewable Heat Incentive ends March 31, 2022, replaced by the Boiler Upgrade Scheme (launched by UK Government in April 2022).


  • ASHP can be expensive to install – The cost to install is typically higher than a conventional heating system with costs anywhere between £8 – £20k, typically coming in around £12k (grants may be available to offset, more on this later).
  • They can be noisy – Some models can have noisy outdoor fans that could be problematic with neighbours.
  • Not always suitable – They may not be suitable for all homes and efficiency drops when the outside temperature is below zero, so not always appropriate for especially cold climates unless used with supplemental heat sources. Some models do not come with high-temperature hot water options so additional means of heating water might be required.
  • Only suitable for homes with outside space – External units can be large in size requiring a suitable outside space, preferably south-facing and away from any neighbour boundaries so as not to cause issues with unit noise.
  • Home adaptions may be required – Depending on the existing heating system, you may need to give up our cupboard space for a large hot water cylinder and you may need to upgrade radiators in your home as some heat pumps do not heat water as hot as a traditional boiler
  • Homes need to be well insulated – Heat pumps are at their most efficient when running at low temperatures and work best in well-insulated properties, with appropriately sized radiators and with underfloor heating systems. It is advisable to address property insulation and draught-proofing before installing a heat pump as doing so afterwards may result in an oversized and inefficient heating system.

What is output size?

The amount of energy required to operate an air source heat pump is measured in kW. Most air-source heat pumps are between 4kW and up to 15 kW in output. The output required for a house is generally determined by the size of your home and how energy efficient it is.

Everything being equal, a larger home will require a heat pump with a greater output.

With the right-sized system, you should be able to get most or all of your hot water needs all year round from an air source heat pump.

When it comes to heat pumps, bigger is not always better. An incorrectly sized system will not be efficient and may increase operating costs or not be able to produce sufficient hot water for your home.

What size air source heat pump do I need?

MCS-accredited heat pump installers can precisely calculate the ideal size for your home and will recommend a size that is most appropriate.

The following will give you an indication of the range of sizes you might be dealing with:

Property TypeEstimated ASHP Output
1-bed flat/apartment3kW
2-bed house/flat3kW to 5kW
3-bed house – poor insulation7kW to 9kW
4-bed house – good insulation9kW to 12kW
4-bed house – poor insulation12kW to 16kW
5-bed house – good insulation12kW to 16kW
Typical heat pump output requirements

All figures are estimated and should be used as a rough guide. Your requirements will be dependent on several factors including the energy efficiency of the property, the type of heat delivery system, and seasonal weather temperatures.

Installing an Air Source Heat Pump in an Existing Home

It isn’t always easy to switch to an air source heat pump in an existing home, doing so may require certain adjustments to be performed such as new pipework and radiators.

A gas boiler will typically operate at high flow temperatures of approximately 70°C, however, air heat pumps operate at lower temperatures and are better suited to properties with underfloor heating and good levels of insulation and draft exclusion.

Are air-source heat pumps getting better?

As heat pump deployment increases, the technology will inevitably lead to improvements in their design resulting in more energy-efficient units that are easier to install (cheaper installation cost).

It is not hard to imagine we will see air-source heat pumps become of the most efficient and cost-effective alternatives to traditional boilers and become one of the leading renewable heating technologies, helping reduce fossil fuel consumption and energy bills.

Heat pumps work well in cold climates

As can be seen in How heat pump sales are starting to take off around the world – Carbon Brief the highest penetration of heat pumps across Europe is in countries with the coldest climates.

The four European countries with the largest share of heat pumps are:

  • Norway – 60% of households
  • Sweden – 43% of households
  • Finland – 41% of households
  • Estonia – 34% of households

The four countries above are countries that face some of the coldest winters in Europe.

Coming soon:

  • Which is the most efficient air source heat pump?
  • What is the quietest air-source heat pump?
  • Why choose an air-source heat pump?
  • Type-of-use heat pump tariff

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