Air Source Heat Pump vs Gas Boiler: Which is Better for UK Homes?

While gas boilers have stood as a reliable constant, heating Britain’s homes for decades, we’re now seeing an increase in viable alternatives, namely the air source heat pump.

In recent years, consumer attitudes have shifted towards the eco-conscious. This means that greener options, like heat pumps, have started to provide a convenient way for Britain to work towards its national Net Zero carbon emissions targets. But, while 80% of homes have a gas boiler installed, just 1% of homes have a heat pump.

In this guide, we explore the differences between regular gas boilers and air source heat pumps, taking you through their unique properties and helping you work out which is better for your home.

What is an air source heat pump?

An air source heat pump is a heating system that provides hot water and heat for a home using energy from the air outside. This renewable system operates like a refrigerator in reverse, bringing in heat from the outside.

Air source heat pumps contain a refrigerant liquid which is used to absorb heat from air before a compressor can increase its temperature. Once hot, the refrigerant is used to heat water in a central heating system.

These pumps come in two types:

• Air-to-water: heating water for central heating and hot water
• Air-to-air: directly heating the air in a room.

To find out more about how this heating system operates, read another of our guides, called “What Are Air Source Heat Pumps & Why Are They So Popular?”.

Gas boilers: the traditional choice

According to Viessman, gas boilers are found in over 80% of UK homes. But, despite their popularity, they are still misunderstood by many homeowners.

At their most fundamental level, gas boilers function to transfer heat to water that can be pumped around a home, warming it. But how about what goes on inside the boiler? 

Gas boilers are designed to work just like other types of heating; however, since gas is highly flammable,  there are a number of important safety features included in the inner workings of the boiler. These features include a gas burner, a heat exchanger, control technology, a diaphragm expansion vessel, and an exhaust pipe.

The central element is the gas burner, which is switched on/off either manually or when the temperature drops below a certain figure. The burner is connected to the heat exchanger, which warms water before pumping it towards the heating circuit.

Air source heat pump vs gas boiler: key comparison areas

Below, we’ve pitted air source heat pumps and gas boilers toe-to-toe, to see how they fare against each other in terms of cost, efficiency, environmental impact, and more.

Upfront costs

Which are more expensive up front, air source heat pumps or gas boilers? While a new boiler typically costs between £2,000 and £4,500 to install, an air source heat pump is a lot more expensive initially.

According to the government’s Boiler Upgrade Scheme (BUS), air source heat pumps cost an average of £12,600 between July and September 2024. However, the BUS scheme brings down this cost significantly, with grants of £7,500 to those installing a heat pump. That said, depending on your requirements, a heat pump could cost you less than £1,000 if you make use of the grant.

It’s worth noting, though, that in both cases, costs will vary based on:

• The capacity
• The size of your home 
• The EPC rating of your home
• The brand/ model
• The complexity of the installation
• Any additional work needed during the installation.

Get a quote for a new gas boiler or a new air source heat pump for your home here.

Running costs

A lot of scientific research and testing has been carried out to form an accurate picture of how much gas boilers and heat pumps cost to run throughout the year; this is known as the seasonal coefficient of performance, or ‘SCoP’.

A recent study by the Energy Saving Trust revealed that running a heat pump would be £14 a year more expensive than using a new A-rated gas boiler. However, when compared to an older G-rated gas boiler, heat pump users would save £340 a year. 

So, it makes sense to switch to heat pumps if you have an older gas boiler that’s not running very efficiently. If you have a new boiler, though, you might want to wait before making the switch

Efficiency

In terms of efficiency, air source heat pumps come out on top, being much more efficient to run than gas boilers. Since heat pumps can extract and transfer heat from the air, they can reach efficiencies of 100%, while gas boilers have an efficiency range of around 78% to 98%. 

It’s worth noting that gas boilers are increasingly coming with features that allow them to release fewer emissions and reduce energy consumption. However, heat pumps are still more efficient, especially when combined with other home heating systems, such as underfloor heating or large radiators.

Environmental Impact

Are heat pumps better for the environment than gas boilers? In short, yes; and here’s why. Air source heat pumps are powered by electricity — not gas — meaning they have a much ‘greener’ fuel source, since 38.2% of the electricity from the National Grid is zero carbon (and this figure will increase with time). Since no fossil fuels have to be burnt to power heat pumps, their production of energy is key for decarbonising our homes and reducing personal carbon footprints.

Air source heat pumps are also more energy efficient than gas boilers, using less energy to produce the same amount of heat, winning them the green point there too.

Installation requirements

Generally speaking, gas boilers are quicker to install and have fewer installation requirements than air source heat pumps. Gas boilers take no more than a day to install, whereas air source heat pumps can take up to a week. This is because a suitable place to put the heat pump unit will need to be settled on, and your pipeworks and radiators may need upgrading. 

Are heat pumps suitable for every home in the UK?

Air source heat pumps are suitable for almost all homes in the UK, with few exceptions; even older homes or flats can benefit from air source heat pumps. However, some homes may need to undergo minor works to ensure they are compatible with heat pumps before installing; this might look like improving insulation and upgrading pipework or radiators. 

 

Government support and future regulations

As we mentioned above, the UK Government currently has the Boiler Upgrade Scheme, which offers grants of £7,500 to homeowners making the switch from fossil fuel heating systems  (oil, gas, or electric boilers) to heat pumps and biomass boilers. You can check if you’re eligible on the government website here.

This grant is in line with the government’s target of installing 600,000 heat pumps a year by 2028 to help support the wider Net Zero goals. While it’s unknown what additional financial incentives may be available in the future, the UK heat pump market grew by nearly 50% in 2021, and we can expect to see continued growth in the years to come. 

 

Which heating system should you choose?

The right heating system for you depends on your home, your budget, and your needs. 

For lower upfront costs, quick installation, and if you’re not looking to upgrade your radiators, you might want to stick with a gas boiler. However, it's worth remembering that gas boilers are less energy efficient and have higher operating costs in the long run when compared to air source heat pumps.

For greater energy efficiency, environmental friendliness, and lower running costs, you might want to make the switch to an air source heat pump for your home, if you can afford the upfront cost and don’t mind the disruptive installation.

 

Final thoughts: is it time to make the switch?

Wondering whether to make the switch from a gas boiler to an air source heat pump? Talk things through with the heating experts at Swale Heating, or visit our Air Source Heat Pumps page for more information about how this heating type works.