These days, renewable energy is becoming an increasingly important trend in most industries — including the home heating market. Considering that, it’s no wonder that ASHPs — Air Source Heat Pumps — have gained in popularity, especially compared to gas boilers.

And unlike a gas boiler, these air source heat pumps run on electricity instead of gas. However, the efficiency of their vapour compression cycle allows them to produce 300% more heat than the electricity they consume; making them a worthy long-term investment.

Even with that in mind, though, you may find the choice of your air source heat pump a difficult one — the industry is constantly expanding, and there are plenty of choices available on the market. Don’t worry, though — we’re here 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
• 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 of high-quality, cutting-edge solution.

The Daikin Altherma 3 series is currently their most popular solution among the company’s air source heat pumps. The Altherma 3 R is the low-temperature version, but there’s an equally great Altherma 3 H HT that’s more compatible with older central heating systems. The output of the units varies between 4kw and 18kw, so there’s a model for 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 that’s gained a sizable following among UK homeowners. Their F2040 series has been given the highest possible energy efficiency rating — A+++.

Also, the 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.

Still, it’s worth pointing out that this series only has low-temperature heat pumps, and they’re 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 needs no particular introduction — they manufacture everything from high-quality mobile phones and TVs to, yes, air source heat pumps.

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

There are units with outputs ranging from 4kw to 16kw, and all with A+++ ErP efficiency ratings. Also, there are special TDM plus units that are an exclusive Samsung patent — outdoor units that provide both hot running water and hot air inside your property, for which you’d need two individual outdoor units with other manufacturers.

Vaillant aroTHERM

Key features:

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

If you’re looking for a brand that couples British manufacturing with efficient German engineering, you won’t do much better than Vaillant. And while this brand has made their name by creating world-class gas boilers, they’ve also branched out into a wider range of heating and cooling appliances — including heat pumps.

Their (perhaps awkwardly named) aroTHERM is the most popular Vaillant air source heat pump — eco-friendly, easy to install, and Quiet Mark approved, meaning you won’t have any hassle installing or maintaining it.

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. Nevertheless, Viessman has a great reputation both among installers and homeowners — and their Vitocal range 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 last of the three is a compact monobloc model with the 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 modern properties.

Grant Aerona R32

Key features:

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

Grant is another international brand that has fully embraced a 2050 zero-carbon goal, and that’s clear from the very name of their Aerona R32 lineup — all of its models use the R32 refrigerant. You can also choose from a wide range of outputs — from 6 to 17kw.

Their 7-year warranty is also 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 their award-winning vehicles, Mitsubishi also manufactures some fairly eco-friendly air source heat pumps — and their Ecodan range is their most popular one in the UK.

It includes a variety of R32 refrigerant models, and many of them are designed to be ultra-quiet. Plus, there’s an entire selection of special “coastal protection” pumps that are resistant to degradation as a result of salty water. The Ecodan R744 is a notable standout here; a small outdoor unit that uses one of the most eco-friendly (GWP 1) refrigerants — 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.

The Therma V range is ideal for the cooler UK climate — and apart from excellent (A+++) energy efficiency, it also 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 pretty famous Japanese manufacturer, regarded for its well-designed, high-quality products.

When it comes to their air source heat pumps, the Hitachi Yutaki lineup is their most important one. Its high water temperatures (up to 80°C) are the series’ most remarkable feature. Also, 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 also extremely energy-efficient, judging from their A+++ rating. Plus, the pumps are easy to install and maintain.

Best Air Source Heat Pumps Buyers’ Guide

As their name suggests, these ASHPs extract heat from the air surrounding your home, even in extremely low temperatures. And they convert this heat into energy that’s used to power the heating inside of your home, and your hot water. This is a complex technical process, and ASHPs are an amazing feat of engineering.

However, that means you may not understand the most important features and distinctions between different air source heat pump models — so we’ll explain the crucial ones you need 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, and air-to-water units use the heat they generate to heat water, which is then circulated to radiators for heating and stored in cylinders.

So, air-to-water units have a single purpose: 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 air. Bear in mind that these are much more difficult to install compared to air-to-water models, which is why we’ll mostly focus on the more practical air-to-water heat pumps.

Temperature

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

Split vs. Monobloc

Temperature isn’t the only way we can differentiate between air source heat pump models. You can also choose between split and monobloc models. The latter comes in the form of a single outdoor unit, while the former has both an indoor and an outdoor unit.

There are several pros and cons to both, but 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.

They’re 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

Eco-friendliness is a big selling point of air source heat pumps — however, they’re not all equally great for the environment. The refrigerants used in their vapour compression cycle are the only element 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 different output sizes between various 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-bed house will require a minimum 9kw output, a 1-bed 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 ones to choose from. Whichever one you end up buying, just 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.