The Future of Heating - Air Source Heat Pumps Explained
If you are looking to slash your heating bills by up to £450 while reducing your carbon footprint by 2 tonnes of CO₂ every year, then the answer might lie in having new heating technology installed. Air source heat pumps deliver all this without the complication associated with a ground source heat pump.
Air source heat pumps have become the go-to choice for eco-conscious homeowners in light of ever-increasing energy costs, while the UK government pursues its ambitious net-zero 2050 goal. Heat pump installations in the UK increased 56% in 2024 compared to 2023, a signal of the widespread utilization of the technology. If you have been considering upgrading to a more efficient renewable heating system in place of your old gas boiler, this blog is for you. We will explain everything you need to know, including how they operate, whether your house is suitable for them, and whether you qualify for free government installation of the new system.
Fill in our quick and easy 1-minute form to see if you qualify for a free ASHP installation under the ECO4 scheme
With efficiency ratings of up to 300% or higher, a typical air source heat pumps produces three to four times as much heat energy as it consumes in electrical energy. This is what makes them so appealing. You can understand why so many households in the UK are switching when you compare that with a conventional gas boiler, which, if highly efficient, runs at about 85-90% efficiency.
Because air source heat pumps work effectively at temperatures as low as -25°C, they are suitable for the UK climate. They are quiet, require very little maintenance, and can last for an average period of 20 to 25 years. Most notably, they do not emit carbon dioxide directly; the overall carbon footprint will depend on the methods of generating power in the electricity grid.
All that suggests this system is a sensible and effective heating option that will increase your energy independence at the same time as keeping the expenses for it in check.
A large fan on the outdoor unit of your air source heat pump draws air in from outside into the system. A heat exchanger within the system converts the thermal energy contained in this air into a refrigerant liquid that circulates through the system. In most systems, when the refrigerant draws heat out of the ambient air it becomes a gas.
This refrigerant gas is then compressed using an electrical compressor, which significantly raises its temperature. It is here that the innovative feature of the system kicks in. The refrigerant would be heated through compression, but when that heat mixes with the heat already absorbed from the surrounding air, what emerges is a powerful heat source.
The heated refrigerant circulates through a heat exchanger, giving off this heat to the heating circuit in your home. Depending on the system installed, this either heats the water for your central heating or, in the case of an air-to-air system, blows warm air directly into your home. Once the refrigerant has given up its heat, it cools down and converts to a liquid to start the cycle again.
The major advantage is the fact that, instead of generating heat with combustion, the air-source heat pump merely transfers heat with electricity. Therefore, the average indoor temperature of a home is going to be much warmer than the temperature outdoors. Because of that, the heat pump uses just small amounts of electricity to upgrade this natural thermal energy. This high efficiency is responsible for the success of the thermal pump.
Today’s systems are incredibly complex: They are fitted with smart thermostats and controls that change performance depending on the requirements of your home and the time of day and weather.
Some models are even capable of reversing the process come summer, to cool your house with air conditioning
The most persuasive reason for all homeowners, however, is the significant reduction in energy expenditure. According to the Energy Saving Trust, the average homeowner can save between £260 and £450 annually by replacing an outdated gas boiler with an air source heat pump. Those who replace oil boilers realize even bigger savings, of up to £650 annually. Households in areas using LPG for heating could therefore enjoy savings of up to £1,410 annually.
A typical air source heat pump costs in the region of £855 to £1,700 a year to run, depending on your house size and heating needs. This stands in good contrast to electric heating or oil boilers, which have annual running costs upwards of £2,000. Factor in full funding under the ECO4 scheme and the £7,500 government grant available with the Boiler Upgrade Scheme, and the effective upfront cost drops dramatically, meaning your savings kick in much faster.
Moving from a mains dependent gas boiler to an air source heat pump leads to a saving of approximately 2 tonnes of CO₂ emissions per year. Extrapolated over a typical life of 20 years, this would equate to 60-100 tonnes of carbon dioxide, an important contribution to the UK’s net-zero 2050 target.
One recent study showed that air source heat pumps could emit 95% fewer carbon emissions each year compared to conventional gas boilers. The heat pump in this study emitted just 250kg CO₂ equivalent during the year in a four-bedroom home, against more than 3,500kg for a conventional gas boiler.
The environmental benefits of air-source heat pumps will only grow with the greening of the UK’s electrical grid, currently with nearly half of all electricity generation coming from renewable sources. Zero-carbon heating can be successfully achieved by homeowners by combining a heat pump with solar panels or a renewable electricity tariff.
Unlike gas boilers that contain lots of moving parts and need regular servicing, air source heat pumps are pretty low maintenance. The majority of maintenance is pretty basic, as ASHPs contain much fewer moving parts; this usually involves the cleaning of the outdoor unit, making a monthly filter check, and the occasional professional servicing once every 2-3 years, although some warranties do call for annual checks.
With proper care, air source heat pumps will consistently last 20 to 25 years. This longevity makes them a truly long-term investment in comfort and efficiency for your home.
They do not use fuel. Therefore, they do not produce carbon monoxide, nor do they need gas pipework. Because of this, they are much safer to use for heating compared to the traditional boiler, which makes them particularly great for homes with young children or elderly family members.
Well-insulated new builds are suitable for ASHP installations. These modern homes are built to current building regulations and are so well-insulated that they are ideal for low-temperature heating systems. In these properties, heat pumps can actually deliver their maximum efficiency and savings. Other ideal conditions for heat pump installation are found in homes that undergo major renovations either by installing underfloor heating, new radiators, or better insulation. Heat pumps are also ideal for properties with underfloor heating systems since these are more comfortable and efficient compared to conventional radiators.
Another important consideration is that one should have multiple options available for placing the external units outside in a well-ventilated area, where usually 2m x 1m space is needed to accommodate the installation with ease.
Improvement Strategy: Loft insulation-cheapest, cavity wall insulation, double glazing installation before the fitting of heat pumps.
If you qualify under the ECO4 scheme, all insulation upgrades, plus any additional improvements such as larger radiators where required, are free! Complete our simple 1-minute form and see if you’re eligible today!
With limited outdoor space, there might not be an appropriate position for the external unit on an urban property. Some buildings have restrictions that involve planning; others are structural. Discuss feasibility with installers before committing to the upgrade.
These properties have additional planning controls. It is still possible to install heat pumps, but aesthetic considerations or planning might make projects more complicated. This should be discussed with your surveyor when making an initial assessment.
In older homes with particularly low electrical capacity, any upgrade in supply may need to be made first before the installation of the heat pump is pursued; this can add another £500-£2,000+, depending on the property and its requirements. This, again, your surveyor would identify.
If eligible for the EC4O scheme, your survey is done free of charge!
Different air source heat pumps have different features. You will be able to select the system which most suits your property, through consideration of the three main types:
Like air conditioning in reverse, air-to-air heat pumps transfer heat from outside air directly throughout your house using ductwork and internal fans.
It is generally the cheapest option, ranging from £4,000 to £9,500 depending on the size of a house and the capacity of the system.
In essence, these systems replace your normal boiler but retain your radiators and pipes by extracting heat from outside air and feeding this into your existing central heating system.
They usually cost in the range of £9,000-£15,000 for a three- to four-bedroom house. That makes them more expensive than air-to-air systems.
In hybrid systems, there is a combination of a gas boiler and an air-to-water heat pump with smart controls that automatically switch between the two units, based on demand and outside temperature. The heat pump can operate independently in good conditions, when the weather is milder, say. The gas boiler provides additional heating when there is extreme cold or high demand.
They generally cost in the range of £7,500 to £11,000. Note, though, that hybrid systems are not covered under the Boiler Upgrade Scheme.
| Heat Pump Type | Typical Efficiency | Potential Savings | Notes |
|---|---|---|---|
|
Air Source Heat Pump (ASHP) |
around 3.0 to 4.5 depending on model and climate
|
Can save up to 50% on heating bills
|
Most common type in the UK. Eligible for ECO4 and BUS grants
|
|
Ground Source Heat Pump (GSHP)
|
around 4.0 to 5.0 or higher
|
Savings up to 60% or more
|
Higher installation cost but very efficient year-round
|
|
Water Source Heat Pump
|
up to 5.0 or more
|
Significant savings, up to 50%
|
Most efficient type but needs water source nearby; Less common
|
|
Air-to-Air Heat Pump
|
generally less efficient than ASHP
|
Moderate savings, best for small spaces
|
Cheaper to install, mainly heats air not water; not usually grant-eligible
|
|
Hybrid Heat Pump
|
Varies
|
Potentially 30-50% savings
|
Uses heat pump as primary source, boiler as backup; good for very cold climates
|
Unlike ground source systems, the installation of an air source heat pump is a very straightforward process, but knowing what happens can help you prepare your home and understand what to expect.
Most air source heat pump installations take from 2 to 5 days, depending on your property:
| Type of home | Days needed for full installation |
|---|---|
|
1-bedroom apartment
|
2 days
|
|
2-3 bedroom homes
|
2-4 days
|
|
3-5 bedroom homes
|
3-5 days
|
|
Large or complex properties
|
5+ days
|
A full site survey assessing heat loss will be done by a qualified engineer before commencing the installation to determine the correct system size in kW, the present heating system, insulation assessment to determine whether any upgrade is necessary prior to the installation, and the electrical supply check to ensure your home has adequate capacity.
They can survey a location outside that will suit the external unit, which needs to have 2m x 1m of clear, level space with good airflow. They can also test the radiators if it is an air-to-water system because you may need larger radiators.
This estimate provides your system specs, overall costs and any preparation work that must be completed.
A full site survey assessing heat loss will be done by a qualified engineer before commencing the installation to determine the correct system size in kW, the present heating system, insulation assessment to determine whether any upgrade is necessary prior to the installation, and the electrical supply check to ensure your home has adequate capacity.
They can survey a location outside that will suit the external unit, which needs to have 2m x 1m of clear, level space with good airflow. They can also test the radiators if it is an air-to-water system because you may need larger radiators.
This estimate provides your system specs, overall costs and any preparation work that must be completed.
If you do not fit into the ECO4 scheme, ensure that you employ a trusted and experienced installer who will ensure all regulations and laws are adhered to. This will ensure the system works safely and in the most efficient manner possible. Warmer Homes Grant has fitted thousands of heating systems throughout the UK, using only Gas-Safe registered installers and the finest quality systems and materials!
The outdoor heat pump unit will be sited on a flat concrete base or wall bracket in the location identified at survey. It’s usually about 2m x 1m in size, which is about the size of two washing machines side by side. It is fixed with specialized attachments to make sure it is stable and secure.
Insulated copper pipes for the refrigerant and water connections run from the external unit into your home, usually via the cavity wall or along the external walls. Once in, these are routed in a way to ensure minimal visibility. In an air-to-air system, ducting is installed to distribute the heat; in air-to-water, the system connects to your radiators and hot water cylinder.
Any electrical connections that are installed must be installed by a qualified electrician, who will also ensure that the electricity supply to your home can cope with the additional demand of the heat pump. Sometimes, an upgrade in your electrical supply will be required; your surveyor will identify this in advance if it is likely to be the case. The electrical work will be subject to the same building regulations as would apply to the installation of a conventional boiler.
Indoor elements for air-to-water systems-hot water cylinder, controls, manifolds-are installed internally, commonly in an airing cupboard, garage, or utility room, and then connected into your existing heating circuit.
Once all connections have been made, the system is thoroughly tested: Pressure tests to ensure pipework integrity Electrical safety checks Control system configuration Performance monitoring under variable conditions of loading Thorough leak detection
Your installer should provide comprehensive training in the operation of your new system, explain the controls, discuss maintenance requirements, and answer any questions you might have. Full documentation and user guides will be provided along with warranty information.
Air source heat pumps have the potential to revolutionize the heating requirements of UK homeowners, with short-term energy bill reductions, substantial carbon emission cuts, long-term reliability, and government financial support via ECO4 and the Boiler Upgrade Scheme. The ECO4 scheme can give you the added bonus of a free solar panel installation, which could bring your bills to almost zero.
Over their lifetimes, heat pumps can save thousands for homeowners! Though some homes have issues in installing the system, most are straightforward to install, taking 2-5 days with very minimal ongoing maintenance. Unlike complex ground source systems, air source heat pumps suit diverse property types and rarely require planning permission.
However, honest assessment of your home’s insulation, outdoor space, and radiator capacity ensures realistic expectations. Properties with poor insulation may require preparatory upgrades prior to installation.
At Warmer Home Grant, we specialise in helping UK homeowners get the highest amount of funding they are entitled to under government-backed schemes aimed at reducing their bills and carbon emissions.
We understand that trying to navigate through heat pump grants, eligibility requirements, and selection of installers can be daunting, and that’s why we have streamlined the process: taking care of the whole application process and providing support whenever you need it! We will always assess your property and circumstances against the latest grant criteria along with all other funding availability. These efforts helps ensure that you gain access to all funding and upgrades that you may qualify for.
From our friendly team of advisors to professional Gas-safe registered installers, you know you are always in safe hands. If you have any enquiries, please don’t hesitate to contact us. The ECO4 scheme only runs until March 2026 and is a limited funding opportunity. Act now by completing our simple 1-minute eligibility form and secure your new system for free!
| Area Covered | Area Covered | Grant Amount | ASHP Installation Savings | Relevant Info |
|---|---|---|---|---|
|
Boiler Upgrade Scheme (BUS)
|
England, Wales
|
£7,500 off installation costs
|
can reduce installation cost to as low as 500.
|
Must replace fossil fuel heating, valid EPC
|
|
ECO4 Scheme
|
UK
|
100% of ASHP cost
|
Full cost for eligible households
|
Based on household income, benefits and fuel poverty
|
|
Nest Scheme
|
Wales
|
Coverage up to full cost for eligible
|
Potential to reduce bills by up to £800/year
|
For low-income or fuel poor households
|
|
Warmer Homes Scotland
|
Scotland |
Up to £7,500. £9,000 for rural.
|
Annual heating savings of £500–£950
|
Additional support for rural areas, loan options
|
|
Home Energy Scotland (HES)
|
Scotland |
Up to £7,500 grant, or £9,000 for rural, and up to £15,000 interest-free loan
|
Annual savings up to £950
|
Both grant and loan available for eligible households
|
|
0% VAT Incentive
|
UK-wide
|
0% VAT on ASHPs until March 2027
|
average 5% savings on upfront cost
|
Applied automatically
|
