Key Takeways:
- Gas boilers are typically much cheaper than heat pumps
- Despite being 3-4x more energy efficient than gas boilers, with current energy prices heat pumps cost approximately the same to run as traditional boilers.
- Gas Boilers are worse for the environment and the government is looking to phase them out because of this in the coming years.
- At some stage in the not-too-distant future, you may need to identify an alternative heating solution for your home.
Heat Pumps vs Gas Boilers - Making the Assessment
Chances are you are reading this because you need to replace your boiler or are considering doing so, and you want to know if a heat pump will be up to the job.
In this article, we will cover:
- What a heat pump is and how it works.
- The cost to purchase and install a heat pump.
- How energy efficient they are, and how much they cost to run compared to gas boilers.
- Other considerations including the environmental impact of heat pumps.
What are Heat Pumps, and How Do They Work?
The first thing to know is that there are three kinds of heat pumps; air-source heat pumps, ground-source heat pumps, and hybrid heat pumps (which combine the heat pump tech with more traditional fossil fuel heating such as natural gas, oil, and LPG systems).
For the purposes of this article we are going to focus on air source heat pumps and ground source heat pumps because the idea, to a large degree, is to find alternative heating systems that move away from burning fossil fuels.
Both air and ground source heat pumps are types of renewable heating systems that work on the principle of extracting heat from either the air (air source heat pump) or the ground (ground source heat pump) and transferring it into a building.
Air Source Heat Pump (ASHP)
An air-source heat pump extracts heat from the air, even in colder climates. They use a refrigerant cycle that absorbs heat from the ambient air and then transfers it indoors.
ℹ Remember, conventional boilers cannot go below 65°C for safe operation.
An air-source heat pump unit consists of:
- An outdoor fan
- A compressor
- A heat exchanger
- An indoor distribution system (radiators, underfloor heating, or forced air)
How it Works
The refrigerant captures heat from the air, and as it passes through the compressor, its temperature rises. The heated liquid then releases the heat into the indoor space, while the cooled refrigerant cycles back outside to absorb more heat.
Air-source heat pumps are typically more affordable and easier to install than ground source heat pumps, but their efficiency may decrease in very cold weather.
Ground Source Heat Pump (GSHP)
A ground source heat pump utilises the relatively constant temperature of the ground to extract heat. Instead of taking heat from the air, GSHPs use a system of buried pipes filled with a heat transfer fluid (usually a mixture of water and antifreeze) to take heat from the earth.
The pipes can be installed horizontally in trenches or vertically in boreholes, depending on the space available.
How it Works
The fluid circulating through the ground loop absorbs heat from the ground, which is then compressed by the heat pump. That heat is then transferred to the building’s heating system, providing warmth. GSHPs are highly efficient and can also be used for cooling during hot weather by reversing the process.
Heat Pump Versus Gas Boiler – Price and Cost of Installation
The first consideration for most people when comparing gas boilers to heat pumps is the cost of purchase and installation.
Gas Boilers
In the UK you can still buy a gas boiler and have it installed for under £1,000, although most will still be a little bit more expensive than that. Below, is a table detailing average UK boiler prices (with installation)
| BOILER TYPE | AVERAGE COST (with installation) |
|---|---|
| Combi | £1,200 to £4,000 |
| System | £1,300 to £3,500 |
| Conventional | £1,800 to £4,500 |
You can take a deep dive into boiler and fitting costs in our article, How Much Does a New Boiler Cost? + Fitting Cost (2023)
Air Source Heat Pumps
The average cost of an air-source heat pump is usually between £7,000 – £13,000 according to the Energy Saving Trust. However, the heat pump units themselves can be found with prices from anywhere between £2,000-£20,000.
How much it costs to install depends on the size of the property, whether it’s a new build or retrofitting an existing property (much more expensive) and how much ancillary work needs to be done. The Telegraph estimates ASHPs typically cost in the range of £7,000 – £14,000 including installation.
Ground Source Heat Pumps
GSHPs are significantly more expensive than ASHPs. According to the Energy Savings Trust the average cost to purchase and install a ground source heat pump is £14,000-£19,000. The Telegraph’s independent investigation had it even higher at £15,000 – £35,000.
Result
No matter how you slice it, heat pumps are a lot more expensive to buy and install than a traditional boiler. You are likely to pay at least 3-5 times as much on a heat pump as you would on a gas boiler.
Air Source Heat Pump vs Gas Boiler – Energy Efficiency
We now know that heat pumps are much more expensive than gas boilers. But what about energy efficiency, will you be able to save enough money on fuel bills over time that will cover the greater initial investment of purchasing a heat pump?
Gas Boiler Efficiency
Most modern boilers operate between 90%-94% efficiency.
Air Source Heat Pump Efficiency
Air source heat pumps have an energy efficiency of 300%. Which is great, but that efficiency is not currently being realised through savings in people’s bills because of the current price of electricity.
Ground Source Heat Pump Efficiency
GSHPs are even more efficient than ASHPs with an energy efficiency of 400%. But, as with air source heat pumps, this isn’t translating into cheaper energy bills.
Air Source Heat Pump v Gas Boiler Running Costs
EDF Energy did a comparison of the running costs for different types of heating systems in 2023 (based on data from our friends at the Energy Savings Trust).
Despite being three times as efficient as gas boilers the cost saving generated by an ASHP over an entire year is calculated to be just £27. Ideal Home also carried out a similar study.
In their calculation, the average home used 12,000 kWh a year, rather than 18,000kW. They concluded that a 4kW heat pump would cost £654.40 per year to generate that 12,000kW. Using a gas boiler the cost would be £572 per year.
Result
Despite being much more efficient than gas boilers, installing air source or ground source heat pumps will not reduce your energy bills. They may even cause them to rise. This may change in the medium to long term but for the foreseeable future one of the oft-mooted benefits to heat pumps is no longer accurate given the current state of the energy market.
Heat Pump v Gas Boiler – Environmental Impact
Gas Boilers
Gas boilers contribute to environmental impact in the following ways:
Carbon Emissions
Gas boilers burn fossil fuels, such as natural gas or propane, to heat water. As a result, they release carbon dioxide (CO2) and other greenhouse gases into the atmosphere. These emissions contribute to climate change and air pollution.
Non-Renewable Resource Consumption
Natural gas and propane, which are commonly used in gas boilers, are finite resources. Their extraction and combustion contribute to resource depletion.
Nitrogen Oxide (NOx) Emissions
Gas combustion in boilers can also result in the release of nitrogen oxide (NOx) gases. These gases contribute to air pollution and can have detrimental effects on human health and the environment.
Heat Pumps
Heat pumps offer several environmental advantages compared to gas boilers:
Reduced Carbon Emissions
Heat pumps utilise renewable energy sources, such as the ambient air, ground, or water, to extract heat. They do not burn fossil fuels directly, resulting in significantly lower carbon emissions. This contributes to mitigating climate change and reducing air pollution.
Energy Efficiency
Heat pumps are highly efficient in converting electricity into heat. For every unit of electricity consumed, they can produce multiple units of heat (1-3 for air source, 1-4 for ground source), significantly reducing energy waste.
Lower Resource Depletion
Heat pumps rely on renewable energy sources, which are essentially inexhaustible. By utilising heat from the air, ground, or water, they minimise the consumption of non-renewable resources.
Potential for Integration with Renewable Energy
Heat pumps can be combined with other renewable energy systems, such as solar panels or wind turbines, to further reduce reliance on grid electricity and decrease your heating system’s environmental impact.
Result
Heat Pumps are better for the environment than gas boilers. One of the major reasons Heat Pumps have been getting a lot of coverage and attention recently is due to the recent government announcement about restrictions around gas boilers from 2025.
In line with recommendations from the government white paper Heat and Buildings Strategy, the government is undertaking a period of consultation that may lead to a ban on installing gas boilers in new build properties from 2025.
The same paper also outlined the government’s intention to ban gas boilers from installation in existing properties from 2035.
You can read our full article What is the UK Gas Boiler Ban? (2023) for more information, but for the purposes of this discussion, in little more than a decade gas boilers will no longer be an option for you when choosing a new heating system and this is entirely down to the fact that they are fossil-fuel burning systems that are negative for the environment.
Heat Pump v Boiler – Hot Water
Your gas boiler doesn’t just heat your home, it also provides you with hot water for your shower, bath and taps. The question, then, is can a heat pump also provide your home with all its hot water needs?
According to the National Energy Foundation, the answer is no… but it can make a contribution. Whilst a heat pump can obviously heat water, they can not produce hot water quickly enough to provide adequate water flow to showers and taps.
They go on to say “Also, most domestic heat pumps are not designed to be able to provide hot water at the same time as providing space heating, with the demand for hot water taking priority.” As such, this is something that really needs to be at the forefront of your mind if you are thinking about installing any type of heat pump.
Most people just take it for granted that if they have heating they will have hot water – because they’ve only ever had traditional central heating that provides both. But this isn’t the case.
This blog was written in collaboration with Eddie Scoffin, the founder of Boiler Choice. Eddie has been installing boilers for over a decade. With a passion for excellence and customer satisfaction, Eddie’s leadership and expertise have been instrumental in the success of Boiler Choice. His commitment to making the boiler installation process hassle-free for customers has earned him a respected reputation in the industry.
Updated on July 12, 2023
