Air source heat pump: your guide

Air source heat pumps extract heat from the outside air, even in cold temperatures, to warm homes and provide hot water. They offer a highly energy-efficient alternative to traditional heating systems, capable of significantly reducing a home's carbon emissions. Homeowners in England and Wales can also benefit from government grants, such as the Boiler Upgrade Scheme (BUS), to help with the initial installation costs.

What is an air source heat pump?

An air source heat pump (ASHP) is a system that transfers heat from the ambient air into your home, rather than generating heat by burning fuel. This technology works even when outdoor temperatures are low, making it suitable for the UK climate.

How air source heat pumps work

Air source heat pumps operate by absorbing heat from the ambient air using a refrigerant fluid. This fluid then passes through a compressor, which increases its temperature. The heated fluid then transfers its energy to your home's heating and hot water systems. After releasing its heat, the refrigerant cools down and the cycle repeats. This process is highly efficient, as the system moves existing heat rather than creating it. Air source heat pumps can achieve efficiencies of 300% or more, meaning they produce at least 3 kWh of heat for every 1 kWh of electricity consumed. Some modern systems can even reach 500% efficiency, delivering 3 to 5 kWh of heat for every 1 kWh of electricity used. This contrasts sharply with modern gas boilers, which typically operate at around 90% efficiency.

Types of air source heat pumps

There are two primary types of air source heat pumps:

• Air-to-water systems: These are the most common in the UK. They heat water that circulates through radiators or underfloor heating systems and can also provide hot water for your taps.
• Air-to-air systems: These systems provide warm air directly into your home and can also offer cooling in warmer months. They do not typically provide hot water.

Benefits of air source heat pumps

Switching to an air source heat pump offers several advantages, from environmental impact to daily living comfort.

Environmental advantages

Air source heat pumps significantly reduce a home's carbon footprint. By extracting heat from the air rather than burning fossil fuels, they produce fewer greenhouse gas emissions. As the UK's electricity grid becomes increasingly decarbonised, the environmental benefits of heat pumps will continue to grow.

Long-term cost savings

While the initial outlay can be substantial, the high efficiency of air source heat pumps can lead to long-term savings on energy bills. Producing more heat energy than the electrical energy they consume means lower running costs compared to traditional systems, especially when paired with smart energy tariffs.

Consistent home comfort

Heat pumps provide a consistent, gentle heat throughout the home, often operating at lower flow temperatures than traditional boilers. This delivers a steady background warmth, avoiding the sharp temperature fluctuations associated with older heating systems.

Air source heat pump costs and grants

Understanding the financial aspects, including installation costs and available grants, is crucial when considering an air source heat pump.

Initial installation expenses

Typical installation costs for an air source heat pump in the UK range from £7,000 to £15,000 before grants. This figure can vary based on the system type (air-to-air systems are generally cheaper than air-to-water), the size of your home, and the complexity of the installation. For instance, a 3-4 bedroom house might see costs between £7,000 and £13,500.

Boiler Upgrade Scheme

The BUS is a government grant designed to help homeowners in England and Wales reduce the upfront cost of installing low carbon heating systems like heat pumps.

To be eligible, installations must be carried out by an MCS-certified installer. The installer applies for the grant on your behalf, with the grant value deducted directly from your installation quote. You do not apply for the grant yourself.

Running costs and efficiency

While air source heat pumps are highly efficient, their running costs depend on several factors, including your home's insulation, the size of the system, and your electricity tariff. An air source heat pump's efficiency can decline in extremely cold temperatures (below -15°C), though such conditions are rare in most of the UK. Proper sizing and installation are key to achieving optimal efficiency, with a Seasonal Coefficient of Performance (SCOP) of around 3.2 being typical for UK conditions.

Is an air source heat pump right for your home?

Determining suitability involves assessing your property's characteristics and understanding the necessary preparations.

Assessing home suitability

Adequate home insulation is crucial for a heat pump's optimal efficiency and performance. A well-insulated home will retain heat more effectively, allowing the heat pump to operate efficiently and keep your home comfortable. Radiator upgrades might also be necessary, as heat pumps often work best with larger radiators or underfloor heating designed for lower flow temperatures.

Considering hot water needs

Air-to-water heat pumps can provide both space heating and hot water. You will likely need a hot water cylinder to store the hot water produced by the heat pump, as they heat water gradually.

Planning and regulations

For certain heat pump installations, particularly larger systems, you may need to notify your Distribution Network Operator (DNO). Your installer should determine whether your system requires pre-approval from the DNO or if a post-installation notification is sufficient. This ensures the local electricity network can safely manage the additional electrical load. You can learn more about the role of a DNO in our guide, "What is a DNO?".

Installation and ongoing care

The journey to a heat pump-heated home involves careful selection of an installer and understanding the long-term maintenance.

Finding a certified installer

It is essential to choose an installer certified by the Microgeneration Certification Scheme (MCS). MCS certification ensures that your installation meets recognised industry standards and is a prerequisite for eligibility for government grants like the BUS.

The installation process

The installation process typically takes a few days and involves mounting the outdoor unit, connecting it to your indoor heating system and hot water cylinder, and making any necessary electrical upgrades. Your installer will also commission the system and explain its operation.

Maintenance and servicing

Like any heating system, air source heat pumps require annual servicing to ensure they operate efficiently and reliably. A typical annual service costs between £150 and £300 and includes checks, cleaning, and system inspection.

Optimising your heat pump with Fuse Energy

Once your air source heat pump is installed, choosing the right energy supplier and tariff can significantly impact your running costs. Fuse Energy offers smart tariffs designed to help you maximise the long-term efficiency and cost savings of your heat pump. These tariffs are structured to reward you for using energy when it is cheaper and greener, aligning with the operational characteristics of heat pumps.

Managing energy with the Fuse app

The Fuse app provides tools to monitor and manage your energy consumption, empowering you to optimise your running costs and environmental impact. By offering transparency and control over your energy usage, the app helps you make informed decisions about when to run your heat pump, ensuring you get the most out of your system and your tariff. Many homeowners choose to pair their heat pump with a smart meter installation to get the most accurate usage data.

Fuse Energy does not install air source heat pumps but focuses on optimising the energy supply and management for homes that have them.