Air source heat pump explained

Air source heat pumps extract heat from the outside air, even in cold temperatures, and transfer it into your home for heating and hot water. They operate on electricity, offering a low-carbon heating solution when powered by renewable energy. Modern air source heat pumps maintain efficiency in typical UK winter temperatures, addressing common concerns about their performance in colder climates. The UK government's Boiler Upgrade Scheme (BUS) provides grants to help offset the initial installation costs, making this technology more accessible for homeowners.

What is an air source heat pump and how does it work?

An air source heat pump is a heating system that absorbs heat from the outside air and uses it to warm your home and provide hot water. Unlike traditional boilers that burn fuel, heat pumps simply move existing heat, making them a highly efficient and environmentally friendly alternative. This process works even when outdoor temperatures drop below freezing.

Extracting heat from the air

The outdoor unit of an air source heat pump contains a fan that draws in ambient air. This air passes over a heat exchanger coil filled with a refrigerant liquid. Even in cold conditions, the refrigerant absorbs heat from the air, causing it to warm up and turn into a gas.

The refrigeration cycle

Once the refrigerant is a warm gas, it passes through a compressor. The compressor increases the pressure and temperature of the gas. This superheated gas then moves to a condenser, where it transfers its heat to your home's heating system (like radiators or underfloor heating) and hot water tank. As the heat is released, the refrigerant cools down and turns back into a liquid. This liquid then passes through an expansion valve, which lowers its pressure and temperature, returning it to its original state, ready to absorb more heat from the outside air, completing the cycle.

Types of air source heat pumps

There are primarily two types of air source heat pumps:

• Air-to-water systems: These are the most common in the UK. They distribute heat through your wet central heating system, providing warmth to radiators or underfloor heating, and heating your domestic hot water.
• Air-to-air systems: These systems circulate warm air directly into your home via fans, similar to an air conditioning unit running in reverse. They are generally not eligible for the BUS and do not provide hot water.

Key benefits for UK homeowners

Switching to an air source heat pump is a strategic "power play" for UK homeowners, offering a move towards greater energy independence and control. It's about securing your home's heating future and reducing reliance on volatile fossil fuel prices.

Lower carbon footprint

Air source heat pumps significantly reduce your home's carbon emissions compared to traditional gas or oil boilers. By extracting heat from the ambient air, they use electricity more efficiently, especially when that electricity comes from renewable sources. This contributes to a greener home and a lower environmental impact.

Potential for reduced running costs

While the initial investment can be substantial, air source heat pumps can lead to lower running costs over time. Their high efficiency means they produce more heat energy than the electrical energy they consume. This can translate into savings on your energy bills, particularly as fossil fuel prices continue to fluctuate.

Consistent home comfort

Unlike some traditional heating systems that can provide uneven heat, air source heat pumps deliver a consistent and comfortable temperature throughout your home. They operate continuously at a lower temperature, providing a steady warmth rather than bursts of intense heat. This creates a more stable and pleasant indoor environment.

Increased energy independence

By adopting an air source heat pump, you gain greater control over your home's energy. You become less dependent on imported fossil fuels and more reliant on an electricity supply that can increasingly be generated from domestic renewable sources. This strategic shift offers resilience against global energy market volatility.

Air source heat pump costs and grants

Understanding the financial aspects of an air source heat pump is crucial. While the upfront cost can seem high, various grants and schemes are available to make them more affordable.

Typical installation costs

According to Thermal Earth, typical installation costs for an air source heat pump in the UK generally range from £7,000 to £15,000, before any grants are applied. This figure can vary based on factors such as the size of your home, its current insulation, and the complexity of the installation.

The Boiler Upgrade Scheme (BUS)

The BUS is a government grant designed to help homeowners in England and Wales switch to low-carbon heating systems like air source heat pumps. The scheme provides a grant of £7,500 towards the cost of an air source heat pump.

Other potential financial support

Beyond the BUS, some local authorities or energy suppliers may offer additional schemes or incentives for installing energy-efficient technologies. It's worth researching what might be available in your specific area.

Factors influencing overall cost

Several factors can impact the total cost of your air source heat pump system, including:

• Property size and heat demand: Larger homes or those with higher heat loss will require a more powerful (and thus more expensive) heat pump.
• Existing heating system: If you need to upgrade radiators or install underfloor heating, this will add to the cost.
• Insulation levels: Homes with poor insulation may require additional insulation work to ensure the heat pump operates efficiently, increasing the overall project cost.
• Installer choice: Quotes can vary between different MCS-certified installers.

Installation process and suitability

A successful air source heat pump installation begins with a thorough assessment and choosing the right professionals.

Finding a certified installer

It is critical to choose an MCS (Microgeneration Certification Scheme) certified installer. MCS is an industry standard that certifies microgeneration products and installers, ensuring quality and enabling access to government incentives like the BUS. An MCS-certified installer will design and install a system that is appropriate for your home.

Home assessment and insulation requirements

Before installation, a qualified installer will conduct a detailed home assessment. This includes evaluating your home's insulation levels, existing heating system, and overall heat demand. Proper insulation, particularly loft and cavity wall insulation, is crucial for an air source heat pump to operate efficiently and effectively in a UK home. If your insulation is inadequate, the installer may recommend upgrades before proceeding.

What to expect during installation

The installation process typically involves:

1. System design: The installer will design a system tailored to your home's specific needs.
2. Outdoor unit placement: The heat pump's outdoor unit will be positioned in a suitable location, often on an exterior wall or on the ground.
3. Indoor unit and hot water cylinder: An indoor unit and a new hot water cylinder (if required) will be installed, connecting to your existing heating distribution system.
4. Pipework and electrical connections: The system will be connected via pipework and electrical wiring.
5. Commissioning and testing: The installer will commission the system, ensuring it operates correctly and efficiently.

Is an air source heat pump right for your home?

Air source heat pumps are suitable for a wide range of UK homes, but their efficiency is maximised in well-insulated properties. They are particularly effective in homes with underfloor heating or larger radiators designed for lower flow temperatures. An MCS-certified installer can provide a tailored assessment of your home's suitability.

Optimising performance and running costs

Once installed, there are several ways to ensure your air source heat pump runs as efficiently and cost-effectively as possible.

Understanding Coefficient of performance (CoP)

The Coefficient of Performance (CoP) is a key measure of a heat pump's efficiency. It represents the ratio of heat energy produced to the electrical energy consumed. For air source heat pumps, the CoP often ranges between 2.5 and 4, meaning they produce 2.5 to 4 units of heat for every unit of electricity consumed. A higher CoP indicates greater efficiency and lower running costs.

Smart controls and energy management

Using smart controls and energy management systems can significantly optimise your heat pump's performance. These systems allow you to program heating schedules, monitor energy usage, and even respond to real-time energy prices. This smart approach ensures your heat pump operates when electricity is cheapest or when demand is lowest, aligning with Fuse's vision of empowering customers with greater energy control. The average UK home uses around 2,500 kWh of electricity per year, according to Ofgem.1 Understanding your energy usage can be made easier with a smart meter installation.

Impact of electricity tariffs

The electricity tariff you are on can have a substantial impact on your heat pump's running costs. Time-of-use tariffs, for example, offer cheaper electricity during off-peak hours, allowing you to run your heat pump or charge your hot water tank when it's most economical. Fuse's digital-first approach and app can help homeowners optimise their heat pump's performance and cost-effectiveness through smart energy management and tariffs, once installed.

The Radio Teleswitch Service (RTS) for legacy meters is being phased out, with the industry-wide switch-off beginning on 30 June 2025. This means older meters will be replaced with smart meters, which can impact heating controls for some older heat pump systems. Once your current supplier has replaced your RTS meter with a smart meter, you can switch to Fuse and get the latest smart meter technology and a digital-first experience.

Maintenance and servicing

Regular maintenance and servicing are essential to keep your air source heat pump operating at peak efficiency. This typically involves annual checks by a qualified technician to ensure all components are working correctly, clean filters, and identify any potential issues before they become major problems. Proper maintenance extends the lifespan of your system and helps maintain its CoP.

Making the switch to a greener home

Adopting an air source heat pump is more than just a heating upgrade; it's a strategic move towards a more sustainable and controlled energy future for your home.

Long-term value and environmental impact

Investing in an air source heat pump adds long-term value to your property and significantly reduces your environmental footprint. As the UK moves towards decarbonising its heating, homes with low-carbon heating solutions like heat pumps will become increasingly desirable and future-proofed.

Future-proofing your home's heating

With the ongoing shift away from fossil fuels, an air source heat pump positions your home at the forefront of modern, sustainable heating technology. It's a proactive step to ensure your home's heating system remains efficient, compliant, and cost-effective for decades to come, reducing your reliance on traditional, less stable energy sources.

Next steps for homeowners

If you're considering an air source heat pump, your next steps should include:

1. Assessing your home's suitability: Focus on insulation and existing heating system compatibility.
2. Researching grants: Understand available financial support like the BUS.
3. Obtaining quotes: Contact multiple MCS-certified installers for system design and installation.
4. Reviewing proposals: Evaluate efficiency and running costs.
5. Proceeding with installation: Work with your chosen installer and register for grants.
6. Optimising operation: Use smart controls and regular maintenance for maximum efficiency.

Fuse Energy offers Vaillant aroTHERM plus heat pump installation, handling the entire process from planning approvals to final checks. We are MCS and TrustMark certified, ensuring a quality installation. By choosing Fuse, you align with a vision of energy abundance and control, enabling you to optimise your heat pump's performance through smart energy management and tariffs.

References

1. Ofgem. Review of typical domestic consumption values