Air Source Heat Pump

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Air Source Heat Pumps

Air source heat pumps are a common type of heat pump in the UK, with water source and ground source as the other options. 

Air source heat pumps are a great option in any climate. The system works by generating heat from the air, to heat up the home. 

One major advantage of this option is their affordability for individual households, making it a popular heat pump in the UK.

Statistics say that the air source heat pumps take 87% of the total energy sold from heat pumps in the UK.

Since the UK targets heat pumps to help reach Net Zero by 2050, air-source heat pumps are gradually becoming a great asset in the UK.

Though the installation cost of an air source heat pump might be expensive, owners will enjoy great returns through incentives such as the RHI and savings from the low running costs. 

Installing an air source heat pump may cost between £8,000 to £18,000, depending on certain factors. Factors that determine the installation cost of an air source heat pump include:

  • The pump size
  • The  home size
  • The pump brand
  • The home insulation level
  • The performance/efficiency of the pump

How Air Source Heat Pump Systems Work

The best way to understand how air source heat pumps work is to understand how refrigerators work. 

Air source heat pumps work by extracting heat from the air and sending it to a compressor that compresses it into higher temperature. 

The compressed energy – heat – is then sent into a refrigerant fluid. 

The final module of the system is the heat exchanger. 

This is a pipe system that transfers heat to the exact location where it’s needed, such as the hot water circuits, radiators, air conditioners, and the under-floor heating systems.

Air source heat pumps are further classified into two types: air-to-air heat pumps and air-to-water heat pumps. 

Air-to-air heat pumps generate heat from the air and send it to another space. Since the technique is air to air, this makes it reversible. 

With this, the system can also function to cool the home during the summer by transferring heat from inside the house to the outside of the house. 

In this case, the system is rather regarded as a refrigerator. 

As the name sounds, air-to-air heat pumps provide space heating. 

However, the system can also function to heat water when combined with other heating systems, such as a boiler.

Air-to-Water Heat Pump

Air-to-water heat pumps are more versatile than their counterpart air-to-air variant as the former can function to heat both space and water. 

This makes air-to-air heat pumps a more common type of air source heat pump system in the UK.

Though both systems work by following the same principle, air-to-water heat pumps don’t require being combined with other systems before being used for the showers, radiators, and under-floor heating. 

Advantages and Disadvantages of Air Source Heat Pump

If you’re concerned about investing in an air source heat pump, you might change your mind with the several benefits that await you. Here are the pros and cons of air-source heat pumps:


  • Reasonable capital costs
  • High efficiency 
  • Low running cost
  • Low carbon emission
  • Eligibility for government incentives


  • The condensed air can freeze in the pipe at low temperature, disrupting the free flow of heat in the pipe
  • Noise from the outdoor pipes can be disturbing

One way to minimize the common issues with this system is to hire a professional installer. 

A professional installer keeps these problems in mind during installation and puts everything into place to reduce their risk. 

It’s important to also keep in mind that air source heat pumps need adequate maintenance. 

Taking care of your heat pump helps maintain its efficiency and keep the running cost as low as possible.

How Much Does an Air Source Heat Pump Cost?

Again, the cost of an average air source heat pump varies between £8,000 to 18,000, and just as mentioned earlier, the price varies according to the size of the system, the brand, and the system performance.

It’s also worth knowing that installation cost is not the only cost to put into account; you also need to consider the level of alteration the installation can bring to your home and how much this will influence your budget.

Generally, heat pumps are more expensive than conventional boilers like condensing boilers. 

Still, the installation cost of an air source heat pump is relatively cheaper than other heat pumps.

The initial cost of an air source heat pump is about half of the cost of a ground source heat pump.

This is perhaps the major reason most households in the UK prefer air source heat pumps to other heat pump options. 

It’s also important to know that the cost of installing an air source heat pump goes up with certain extra installation or repair costs. 

For example, if you need to install or repair radiators before installing an air source heat pump, you can expect the installation cost to go up.

However, government intervention programs are a relief for households in the UK that want to invest in heat pumps. 

An example is the Green Homes Grant that caters for two-thirds of installation costs of the systems in England. 

What Are the Running Costs?

Other than the installation cost of this system, one other concern is the running cost, and just like the former, the running cost also depends on certain factors, including:

  • the system size
  • your energy expenditure 
  • the outside temperature
  • the system’s efficiency (SCOP)
  • how well insulated your home
  • RHI tariffs

The system itself influences the running cost with its size and efficiency. 

Owners of bigger systems should expect to spend more on running their system than what owners of smaller systems spend. 

The outside temperature is also a significant factor. Though most air-source pumps run in air temperatures around -20°C, they lose their efficiency with temperatures below 0°C. 

With this, air source heat pumps are a great option in the UK since the UK winters go far below 0°C.

On the part of the home where they’re installed, how well the home is insulated and how much energy is needed will influence the running cost of air source heat pumps. 

If your home is well insulated, you can get the most out of your system with less energy consumed. 

Also, the more energy you require from your heating system, the higher your energy bills.

Financing a Heat Pump System with a Grant

Heat pumps are eligible for government’s grants. With an air source heat pump, you’re eligible for the Renewable Heat Incentive (RHI). 

The UK government established the RHI in April 2014 as part of its effort to meet its Net Zero target by 2050. 

This incentive was targeted at helping homes in the UK to generate energy from renewable sources for heating purposes. 

Application for this incentive is open to homeowners, home-builders, and landlords in the UK.

Another financial support for renewable heating systems is the 5% VAT reduction on products that help save energy. 

How Much Return Can ASHP Bring?

Investing in an air source heat pump doesn’t only save you energy, but also saves you money. 

Depending on the efficiency levels at which the system is operated, owners can save up to £1,335. 

High Efficiency Helps Save Money

The efficiency of a heat pump is measured in COP (Coefficient of Performance), which applies to air source heat pumps. 

The COP of most air-source heat pumps varies between 2 and 4 but can increase to 5 in certain cases. 

The COP of a system gives the number of kilowatts of heat to expect from the system with 1 kilowatt of electricity. 

This means that an air source with a COP of 3 will generate 3 kilowatts of heat. 

In another term, say that the system produces three times the amount of heat you generate using electricity.

One major factor that determines the efficiency of this system is the temperature outside. 

An air-source heat pump operated with an outside temperature of  7°C can be expected with a COP of 3.2.

Since the outside temperatures in most parts of the UK fall between 5 and 8°C, air source heat pumps are an effective option in the UK.

To save money on an air source heat pump, your system’s efficiency plays a significant role. 

A system with a higher efficiency has a lower running cost than one with lower efficiency. 

Two factors always determine the running cost of this system: the amount of heat you need for your home and the amount of heat your system can generate. 

Running Costs Savings Calculation

To make this more understandable, we’ll look at a scenario of a four-occupant household and see how much money it requires to run. This example uses a 200m2 detached house.

For a house of this size, we can assume it needs around 10,000kWh for heat and 4,000 for hot water. 

The running costs of an air source heat pump for a detached house of this size will cost £975.

On the other hand, the average running cost of a boiler for a house of the same size will be around £1615. 

Doing the math from here, an air source heat pump can save up to £640 with a house of this size and energy need.

However, most UK houses are not smaller than this size and don’t need up to this amount of energy. 

The average size of homes in the UK is around 76 m2, meaning that your system’s actual running cost may be lower than what we have in this example.

What to Consider Before Buying Air Source Heat Pumps

Air source heat pumps are a great investment on your home, with a lot of advantages that it offers. 

However, it’s important to consider certain factors before venturing into the investment, as the new installation will bring some changes to your house. 

Here’re the common factors to put into account when planning to install an air source heat pump:

Space: the first factor to consider is the available space for the installation. Installing an air source heat pump requires having enough space. 

This is where the external modules are installed, which can be on the wall or the ground. 

To generate enough hot air, the system needs to be provided with enough space around it to ensure proper airflow. It’s ideal placing the heat pump near a sunny wall.

Level of insulation: how insulated your home is, will also determine the effectiveness of your system. 

A heat pump is expected to function well in a more insulated home. 

As such, you need to know if your home is well insulated and consider the cost of installing new insulation to have the most of your heat pump system.

Current energy source: it makes no sense to generate energy from your heat pump if you have a cheaper source of energy installed already. 

The point is to consider if you can save more money by generating heat for your home than from your current heating system. 

When considering this, don’t forget the benefits of the government’s incentives that you’ll enjoy with an air source heat pump.

The available heating system in your home: before you finalize your decision of buying an air source heat pump, it’s smart to know which type will work best for your home. 

You’ll want to go for an air-to-water heat pump if you already have an under-floor heating system.

Other building work: if you’re proposing other building work, you may have to plan it together with your new installation to help reduce the projects’ costs.

It’s important to mention that you can combine this system with another green home solution. 

For instance, combining an air source heat pump with a condensing boiler is a smart idea. 

With this combination, the condensing boiler will function as a backup, which helps boost the performance of your heat pump.

One common and ideal combination is a heat pump with a solar panel system. Solar panel powers the heat pump solar system, which further helps in saving money.