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Best Air Source Heat Pump UK

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If you’ve been looking into heat pumps for a while, then you’ll no doubt have come across various blogs and posts talking about the best air source heat pump, and you’ll no doubt have seen various conclusions on that. But that makes sense, given that different people prioritise different benefits that air source heat pumps bring, and they all bring different benefits to different degrees.

But if you’re looking for a more balanced review focussing on what some of the best air source heat pumps on the market do really well, then you’ve come to the right place. Read on and let Fixx guide you through some of the leading heat pumps, so you can decide which is the best air source heat pump for you. 

What Is The Best Air Source Heat Pump?

As you’ve probably already guessed, at Fixx we don’t think there’s a single best air source heat pump on the market. Instead, we recognise that certain heat pumps are better at certain things, and deciding which is right for you will depend largely on what you prioritise. 

The point is, the best heat pump is the heat pump that works best for you. 

What Factors Affect How Good An Air Source Heat Pump Is?


Most heat pumps are around 300% efficient. That means for every 1kW of energy used to operate the heat pump, it will deliver around 3kW of energy to your home. However, some of the very best on the market can reach around 400%+ efficiency. 

The more efficient your heat pump, the better it will perform for you and the less you’ll have to spend on energy operating it to heat your home. 


You’ll want your air source heat pump to provide enough heat for your home to keep it comfortable. For many, the best heat pump will be the one that suits your energy needs the best, meaning your home stays warm when you need it to. The power output of your heat pump is measured in kW – the larger your home, the higher the number of kW output your heat pump will need to have. 

According to Heat Pumps UK, there is a recommended air source heat pump output based on your property type:

  • 1 bedroom flat: 2-3kW
  • 2 bedroom terrace: 4-5kW
  • 3 bedroom semi-detached: 6-8kW 
  • 4 bedroom detached: 9-11kW
  • 5 bedroom detached: 12-16kW


Although this is a rough guide, it gives you an idea about which heat pump might be best for you based on their power output.


Some areas of the UK can get cold. Like, really cold. And when that happens you need to be certain that your air source heat pump is still going to function as normal. 

Whilst most heat pumps handle the cold relatively well, some can still operate comfortably at -20 C or less, without risk of its efficiency dropping off in the extreme cold. Now, it’s unlikely you’ll ever need your heat pump to operate at such cold temperatures, but since we’re a team that operates throughout Yorkshire, Fixx believes that having a heat pump capable of dealing with the cold probably isn’t such a terrible idea…


When it comes to housing your heat pump, size really does matter. It matters how large the system is and it matters how large the space is outside your home to accommodate the heat pump. It also matters whether or not the air source heat pump is split or monobloc. Monobloc heat pumps are generally larger, but can be housed outside the home in a single unit. Split systems are smaller, but require some internal space for the indoor unit and external space for the outside unit. 

For some customers, then, the very best heat pump is the one that fits. For those with small homes with less internal space or less space on your external wall for a heat pump installation, you’ll want to look out for more compact heat pump systems that can still deliver what you need. 


For others, the most important factor affecting which heat pump they judge to be best is the warranty. Not only does a longer warranty period show the manufacturer’s confidence in their products, but it also protects your investment for longer. 

Most will come with a warranty of between 2 and 5 years as standard, but some heat pump manufacturers may go beyond this. 


We’ve left the big one until last, because whilst we would love to be able to say that the cheapest air source heat pump is the best, it won’t always be the case for everybody. 

But for those who are looking to upgrade their old fossil fuel heating system to a newer, greener option on a budget, then having a cheaper heat pump that performs well enough for your home makes a lot of sense. 

Key Air Source Heat Pump Models

There are a range of excellent heat pumps out there, but below we’ll cover Fixx’s favourites based on the areas they excel in. That way, you can decide what’s most important to you, and then pick the heat pump that matches that best. 

Remember, though, there are multiple heat pump models that perform well in the categories below, and just because we’ve labelled one as ‘Best For’ doesn’t mean there aren’t other models we haven’t discussed today that do it extremely well, too.

For the latest guidance and advice, contact our customer service team. 

Best For Efficiency 

If efficiency is important to you, then the Hitachi Yutaki heat pump is hard to beat. With an efficiency of 500% (meaning for every 1kW of energy used to operate this heat pump, 5kW is produced), this is one of the leading heat pumps on the market, and many of you will recognise Hitachi as a trusted brand, too, given that they’ve been leading manufacturers in the heat pump space for years. 

Best For Power 

When it comes to power, Vaillant flexoTHERM 400V is leading the way. It has a peak power performance of 19kW (when you opt for the 19kW model over the 15kW option) so it’s a wonderful heat pump for those with larger homes that might need a little more power to heat it. It still has excellent efficiency too – over 460% – and can heat water to 65 C rapidly, meaning you get quick results when you need hot water in your home. 

Best For Weather 

The LG Therma V R32 Monobloc is an excellent air source heat pump with a range of benefits, but its main draw is its ability to operate efficiently at even -25 C, so it can handle almost any weather. Not only does it have excellent performance in the cold, but it also has a maximum power output of 16kW, and an efficiency of 400%, meaning it doesn’t compromise on other areas just to bring you a heat pump that can operate in freezing temperatures. 

Best For Size 

Some people require a compact heat pump due to limited space in and around the home – and that’s where the Nibe F2040 comes in. As a monobloc system, you only need space to house an external unit, and as a Swedish company, Nibe specialises in practical designs for heat pumps. It’s currently one of the most popular heat pumps on the market thanks to its cost effectiveness and compact size. But just because it’s small doesn’t mean it isn’t mighty – it’s still incredibly efficient (300%) and powerful too (up to 15.8kW if you opt for its more powerful model). 

Best For Warranty 

The MasterTherm UK BoxAir Inverter hails from Wales, so it’s about as local as it gets. But better still, it has a reasonable enough price tag, is incredibly efficient, and has enough power to heat a three bedroom home (8.65kW max power). But where this heat pump really stands out is its warranty. 7 years standard, outperforming almost all its competitors in this regard. 

Best For Cost 

That old saying ‘buy cheap, buy twice’ doesn’t always ring true, and that’s certainly the case with the Grant Aerona³ R32. Not only is it one of the best value heat pumps on the market, it also performs brilliantly in other areas too. Its efficiency is over 400%, it’s incredibly lightweight, so it’s easier to install than most, and it sits below the average price of  heat pumps which is usually between £7,000 and £13,000 with its price coming in at a little over £6,000 (excl. installation costs). 

Best Air Source Heat Pump: Round-Up

Below you can find a summary of the best air source heat pumps based on the area they excel in…


Heat Pump Best For…
Hitachi Yutaki Efficiency
Vaillant flexoTHERM 400v Power
LG Therma V R32 Monobloc Weather
Nibe F2040 Size
MasterTherm UK Box Air Inverter Warranty 
Grant Aerona³ R32 Cost


The key take-home message from today’s post is that there is no single best air source heat pump out there. What there are, though, are multiple different heat pumps that perform exceptionally well in different areas. Decide which area is most important for you, and you’ll find your perfect heat pump.

Still not sure? That’s ok! Just work with a member of our team at Fixx and we’ll be able to help you decide if an air source heat pump is right for you, and if it is, which one will suit you best.

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