These days, renewable energy is an increasingly important concern in most industries, including the home heating market. With this being the case, it’s no wonder that ASHPs, or Air Source Heat Pumps, have grown in popularity, especially compared to gas boilers.

Unlike gas boilers, air source heat pumps run on electricity, not gas. The efficiency of their vapour compression cycle allows these pumps to produce 300% more heat than the electricity they consume, making them a smart long-term investment.

You may find it challenging to choose the air source heat pump that’s right for you — the industry is constantly expanding, and there are plenty of choices available on the market. But don’t worry, we present you with an in-depth buyer’s guide and a selection of the top 10 air source heat pumps that are worth your time and money.

Daikin Altherma 3

Key features:

• Both monobloc and split varieties
• Low-temperature and high-temperature variants
• Solar compatible
• Low-sound mode that minimizes disturbance

Daikin is one of the most popular heating and cooling product brands in the UK — they’ve been in operation for almost a century, and they have a long-standing tradition as a high-quality, cutting-edge solution.

The Daikin Altherma 3 series is currently the company’s most popular indoor climate solution among the company’s air source heat pumps. The Altherma 3 R is a low-temperature version, and the Altherma 3 H HT is more compatible with older central heating systems. The output of these units varies between 4kw and 18kw, which means there’s a model available to suit any kind of property.

Nibe F2040

Key features:

• Great silent operation function
• WiFi integration and smart technology compatibility
• Works at outdoor temperatures of -20°C

With its 6kw to 16kw output, the Nibe F2040 series is another great air source heat pump to consider.

This Swedish manufacturer is another leading brand in the air source heat pump industry. They’ve gained a sizable following among UK homeowners. Their F2040 series has been given the highest possible energy efficiency rating of A+++.

This brand offers a robust mobile application that helps homeowners manage and maintain their heat pumps, providing quick access to useful information like status updates and overviews.

It’s important to note that these low-temperature heat pumps are all monoblocs — there are no split units, so you’ll need a hot water tank as well.  

Samsung Eco Heating System

• Solar compatible
• A quiet mode for lower outdoor noise
• Works in -25°C weather
• Mono and split units

As a global titan of home appliances, Samsung is a household name. This company manufactures  everything from high-quality mobile phones and TVs to air source heat pumps.

Their Eco Heating System is ideal for mid-sized and smaller properties, with a lightweight, compact design that won’t detract from the interior or exterior decor of your home.

You’ll find units with outputs ranging from 4kw to 16kw, all with A+++ ErP efficiency ratings. Specialized TDM plus units boast an exclusive Samsung patent. These outdoor units bring both hot running water and hot air inside your property (with many other manufacturers,  you would need two separate outdoor units to achieve this).

Vaillant aroTHERM

Key features:

• Range of low-temperature and high-temperature units
• Both split and mono units are available
• Eco-friendly units with R290 refrigerant

If you’re looking for a brand that couples British manufacturing with efficient German engineering, Vaillant Vaillant is for you. While this brand has made its name by creating world-class gas boilers, the company has also branched out into a wider range of heating and cooling appliances — including heat pumps.

AroTHERM is among the most popular Vaillant air source heat pumps. It’s eco-friendly, easy to install, and Quiet Mark approved, meaning you’ll enjoy hassle-free installation and maintenance.

Viessmann Vitocal

Key features:

• Relatively eco-friendly R32 refrigerant
• Advanced acoustic design that ensures quiet operation
• Indoor units with hot water tanks

This German brand has been a key player in the wider European market for heating and cooling appliances, but a relatively new competitor in the UK. Viessman has a great reputation among both installers and homeowners — and their Vitocal series contains a wide variety of air source heat pumps.

There are three main models in this series: the Vitocal 222-A, Vitocal 200-A, and the Vitocal 100-A. The 100-A is a compact monobloc model with R32 refrigerant. And though choosing it means you’ll need a separate storage tank for hot water, it’s a great low-temperature choice for contemporary properties.

Grant Aerona R32

Key features:

• 7-year warranty with accredited installers
• Low-noise design
• All models use R32 refrigerant

Grant is an international brand that has fully embraced a 2050 zero-carbon goal, and this is evident from the very name of their Aerona R32 line-up — all models use R32 refrigerant. You can choose from a wide range of outputs, from 6 to 17kw.

The company’s 7-year warranty is an impressive selling point, but bear in mind that these are low-temperature heat pumps designed to work with low-temp radiators and underfloor heating.

Mitsubishi Ecodan

Key features:

• Ultra-quiet models
• Special units with protection from salt damage for coastal properties
• Decent output range

Best known for award-winning vehicles, Mitsubishi also manufactures eco-friendly air source heat pumps — and their Ecodan range is their most popular one in the UK.

This series includes a variety of R32 refrigerant models, and many are designed to be ultra-quiet. You’ll find an entire selection of specialized coastal-protection pumps that are resistant to degradation from salty air and water. The Ecodan R744 is a notable standout here. It’s a small outdoor unit that uses one of the most eco-friendly (GWP 1) refrigerants, the R744.

LG THERMA V

Key features:

• Monobloc and split options
• Certain units work in -25°C weather
• High-temperature and low-temperature pumps
• R32 refrigerant

This famous South Korean tech manufacturer is responsible for the wide adoption of the eco-friendly R32 refrigerant. Their Therma V line is one of the first that used it instead of the less sustainable R410A, which was the standard before R32 became more commonplace.

The Therma V range is ideal for the cooler UK climate. In addition to running with  excellent (A+++) energy efficiency, it comes with a user-friendly digital interface. With it, you can easily adjust your heating and cooling schedule.

Plus, the LG smartphone app lets you check the Therma V’s energy consumption in real-time and control its basic functions remotely.

Hitachi Yutaki

Key features:

• Maximum hot water temperature of 80°C
• Hot water storage tanks integrated with indoor units
• Outdoor units come with a smart defrost feature that increases energy efficiency

Hitachi is a well-known Japanese manufacturer, regarded for its innovative, high-quality products.

The Hitachi Yutaki line-up consists of the company’s most notable air source heat pumps.  Particularly impressive is the series’ high water temperature rating (up to 80°C). The Hitachi pumps have a special heat pump circuit instead of the standard element used by other manufacturers, which lowers the time needed to reach higher water temperatures.

The Yutaki S80 pumps are extremely energy-efficient, based on their A+++ rating. These pumps are easy to install and maintain.

Best Air Source Heat Pumps Buyers’ Guide

As their name suggests, air source heat pumps (ASHPs) extract heat from the air surrounding your home, even in extremely low temperatures. They transfer this heat into your home to provide you with heated indoor air and to heat your water. This is a complex technical process, and ASHPs are an amazing feat of engineering.

To help you understand the most important features and distinctions between different air source heat pump models, we  explain several key concepts so that you know what to examine before buying one.

Type of air source heat pump

There are two types of ASHPs: air-to-water and air-to-air. The air-to-air models use a system of fans to cool or heat your household. Air-to-water units use the heat they generate to heat water, which is then circulated to radiators for heating and stored in cylinders.

Air-to-water units have a single purpose: to generate heat from the outside air and transfer this heat to the water that runs through your central heating system. On the other hand, air-to-air pumps are more akin to air conditioning units that can be used to heat or cool your indoor air. Bear in mind that these are more difficult to install than air-to-water models, which is why we focus primarily on the more practical air-to-water heat pumps.

Temperature

Most manufacturers of air source heat pumps create two different types: low-temperature and high-temperature. The low-temperature pumps are designed for households with low-temperature radiators or underfloor heating. High-temperature units are better suited for the usual central heating systems, since they heat up water to temperatures equivalent to those of a gas boiler.

Split vs. Monobloc

Temperature isn’t the only way to differentiate between air source heat pump models. You can also choose between split and monobloc models. Monobloc products take the form of a single outdoor unit, while split pumps include both an indoor and an outdoor unit.

There are several pros and cons to both. Basically, it comes down to this: monobloc air source heat pumps take up less space inside your home compared to both a gas boiler and a split unit, because there’s no indoor unit.

Monobloc pumps are also much easier to install (and thus less expensive) because they’re self-contained and require no refrigerant pipes to connect to an indoor unit. In turn, this also makes them easier to maintain.

However, most monobloc air source heat pumps require you to install a hot water storage tank separately — while the indoor unit in a split air source heat pump is likely to have integrated hot water storage.

Eco-friendliness

For many conscientious consumers, eco-friendliness is a big selling point of air source heat pumps — however, not all pumps are equally great for the environment. Generally, though, the refrigerants used in their vapour compression cycle are the only elements of ASHPs that could potentially have a negative impact on the environment, reflected in the GWP (global warming potential) of these gasses.

For comparison, carbon dioxide has a GWP value of 1 — and R290 is the most eco-friendly refrigerant with a GWP of 3. Next up, there’s the R32 with a 677 GWP, and R410A as the least environmentally friendly option, with a 2088 GWP.

Output size

There are various output sizes available between different air source heat pump models, expressed in kw (kilowatt). The output range you choose will depend on the size of your home. While a 4-bedroom house will require a minimum of 9kw output, a 1-bedroom flat will find a 2kw ASHP to be sufficient.

Wrapping Up

As you can see, there are plenty of choices when it comes to air source heat pumps — and the ones we’ve listed here aren’t the only great options available. Whichever you end up buying, make sure you’ve taken all the important factors into consideration, such as the needs and size of your household, and the pump’s energy efficiency, output, price, and warranty.