Recent UK boiler statistics show that the boiler insurance market is worth an estimated £519.3 million, as of 2023. This is expected to reach £1.06 billion by 2028 – growing at a compound annual growth rate (CAGR) of more than 15%.
23 million homes in the UK have a gas boiler to supply their central heating and hot water. Repairs to these systems can be costly, therefore by comparing boiler cover deals on the market, you can protect yourself against any unexpected expense in the future.
Our research has collated various UK boiler facts and stats for 2023, to analyse trends, judge how the UK boiler market has evolved over time, and make predictions about the future of home heating in the UK.
Quick overview of UK boiler statistics 2023
The UK boiler insurance market is worth over £500 million
23 million UK homes have a gas boiler
UK domestic boiler sales increased by over 40% between 2020-21
80% of UK households have combi boilers
78% of UK residents use gas central heating in their homes
Over 95% of UK households have a central heating system
The cost of a new boiler in the UK can vary between £600 and £10,000
The boiler replacement cost in the UK is likely to be between £1,500 and £5,000
A typical gas boiler replacement (boiler and fitting) in the UK costs around £4,000.
Boiler market statistics
The global commercial boiler market was projected to be worth £3.18 billion by the end of 2022, with a compound annual growth rate (CAGR) of 4.81% from 2021. Its value is anticipated to grow by a further 5.12% over the next three years, to £3.88 billion by 2026.
According to UK boiler market statistics from the Heating and Hotwater Industry Council (HHIC), sales of UK domestic boilers hit almost 675,000 for the first four months of 2021—a 41% increase from the same time in 2020, when more than 476,000 units were sold.
The 12-month rolling average for the financial year ending 2021 was in excess of 1.75 million units, compared to 1.54 million units a year earlier—an increase of 14%.
80% of boilers sold in the UK are combination heat and water boilers (also known as combi boilers), where the home has no hot water cylinder.
A breakdown of how people in the UK intend to heat their home during the winter of 2022
During the winter months, over two-thirds (78%) of UK residents use gas central heating to heat their homes. The next most popular options are electric storage heaters and oil central heating, both with a 5% share.
In 1970, only 30% of UK houses had a central heating system. This increased to 95% by 2005, and has remained relatively constant since.
Reasons for growth in the UK boiler market
According to boiler statistics, the commercial and domestic UK boiler market is projected to grow considerably between 2022-27.
This is largely driven by high demand from commercial buildings, such as:
Office blocks
Healthcare establishments
Educational institutions
Retail spaces
Lodgings.
There is also a higher demand for clean-heating systems, as more investment goes into making buildings as ‘green’ as possible through various eco-home renovations. For example, natural gas used in boilers leads to a reduction in greenhouse gas emissions. With a range of green energy suppliers now on the market, this has increased the competition and driven down prices for the consumer.
Government policies that promote the development of gas infrastructure, and stricter emission regulations, will help bolster the demand for clean, energy-efficient energy systems and contribute to market growth.
Moreover, the increasing need to replace existing, less efficient systems with more advanced boilers will also help to drive up demand.
According to the Construction Leadership Council (CLC), the Russian invasion of Ukraine could lead to some uncertainty, with regard to the rising cost of components and associated supply issues.
In March 2022, the CLC announced stock levels and availability were good for a number of industrial products, despite rising demand in the first few months of the year. However, boilers were identified as one of the key products experiencing supply chain issues and delays.
Some UK boiler manufacturers were experiencing electricity fluctuations of up to 300% daily in 2022, which had a knock-on effect on productivity in the winter months of that year. However, supply chains returned to normal in 2023, with availability increasing by 20% in January 2023 (compared to the same time the previous year).
The supply chain issues in 2022 were coupled with other issues, such as:
Transport delays affecting the import of raw materials and products, with some merchants reporting that only 25% of goods turn up on time
Increased demand for solar panels and renewable energy products
Shortage of certain materials, such as barrier pipe and glass
Price inflation and the rising cost of living.
Cost of boilers in the UK
How much does a new boiler cost in the UK?
According to recent UK boiler statistics, a new boiler can be purchased for as little as £500. However, this doesn’t include installation costs or any additional work to make way for your new boiler, such as fitting new pipes, altering existing ones, or adding a control system.
Budget boilers can cost between £500-£900, while premium models tend to start around £1,300.
A breakdown of the average cost of different types of boilers in the UK in 2023
The cost of a new boiler will also depend on the type of system you wish to have installed. The cheapest options, based on boiler costs alone, are likely to be a system boiler (averaging at just over £1,300 exc. VAT), followed by a combi or LPG boiler (both around £1,500 exc. VAT).
However, cheaper boilers tend to be less powerful, and are suited to smaller properties. A 24-30kW boiler is suitable for any home with up to three bedrooms, whereas larger houses require a boiler that is 35kW or more.
The more expensive options available are generally biomass boilers (around £10,000 exc. VAT), followed by condensing boilers (around £2,500 exc. VAT).
How much is a boiler replacement?
The cost of replacing a boiler can vary depending on a number of factors, such as:
Type of boiler you want to install
Brand and model
Size of boiler
Length of warranty required
Labour costs
How complicated the installation process is
How much work needs doing
Parts needed and their availability.
The cost is likely to exceed £1,500, but could rise to nearer £5,000 depending on the factors outlined above.
Typically, a straightforward gas boiler replacement, including thermostatic radiator valves, will set you back around £4,000. The equivalent of replacing an oil boiler is around £4,700.
While you may be able to pick up a boiler for between £500 and £2,500, this will not include labour costs. A boiler engineer may charge around £300 per day to install a new boiler. Standard jobs, like swapping like-for-like boilers, can usually be completed in a day by a single fitter, whereas more complex jobs, such as converting a back boiler to a combi boiler, could take a couple of days and/or require more than one person.
Additional costs could involve:
New/replacement pumps and/or valves ( £180-£220)
Fitting smart thermostats ( £120-£220)
Boiler magnetic filters (£350-800)
Chemical cleanse of existing pipes for increased efficiency (£350-£800).
Types of boiler and their associated costs
The UK boiler market consists of boiler systems used to provide heating and hot water to domestic buildings, either through the use of electricity or burning combustible fuel.
With so many different products on the market, choosing the right type of boiler for your home might feel overwhelming.
The two main types of boilers in the UK boiler market are:
Fire tube - where a hot flue gas is present inside tubes surrounded by water.
Water tube - where the opposite occurs, and the water is heated by travelling through a tube surrounded by hot flue gas.
Domestic heating fuels can include natural gas, coal, oil, liquified petroleum gas (LPG), and others by utilising technologies such as condensing and non-condensing systems.
The launch of innovative boiler systems is starting to gain momentum in the UK boiler market, such as the introduction of low, nitrous oxide boilers, and high-efficient boilers with compact designs, reduced carbon footprints, and easy installation.
Boiler cover and boiler insurance
Boiler and central heating cover can also be a good way to help protect you from unexpected bills. This will ensure you never have to go too long without hot water and heating—especially in the colder, winter months.
There are lots of different types of boiler cover available on the market, from covering just your boiler and heating controls to full central heating cover that protects your whole heating system, including hot water.
Choosing the right boiler insurance will help guarantee that you’re covered, should the worst happen. This prevents you from paying over the odds for a new boiler when you least expect it.
Applying for boiler cover couldn’t be simpler. With a range of companies available on the market, you could opt for a well-known product, such as the British Gas Homecare boiler cover, which has over 6,000 Gas Safe registered engineers across the UK. Or you may decide on a lesser-known, slightly cheaper alternative.
Check out our guide containing questions and answers about boiler cover to help select a product that is right for you, or alternatively our top tips for choosing your heating cover.
How much does a new combi boiler cost?
Upgrading to a combi boiler adds a premium of around £750 on top of the standard boiler cost. Depending on other factors, this could bring your overall boiler replacement cost to anything between £2,000 and £4,500.
This will generally include the removal of your old boiler and water cylinder, as well as any pipe upgrades.
You may be charged more if you want to switch from a back boiler to a combi boiler, as this involves moving the new boiler to a different location. Therefore, a back boiler upgrade could cost anywhere between £3,000 and £5,000.
The cost of a new combi boiler will also depend on the type you decide to purchase.
A breakdown of the average cost of different types of combi boiler in the UK
| Type of combi boiler | Average associated cost (exc.VAT) |
|---|---|
| Gas | £2,400 |
| Electric | £1,100 |
| Oil | £3,675 |
(Source: Checkatrade)
Oil combi boilers are usually the most expensive option, costing over £3,600 to install. When it comes to gas vs. electric heat costs, gas is normally twice as expensive by comparison (£2,400 vs £1,100). But then again, this will depend on the type of electric boiler you wish to purchase.
A breakdown of the cost range of different types of electric boiler in the UK
| Type of electric boiler | Power | Cost range | Average UK cost |
|---|---|---|---|
| Without in-built cylinder | 12kW | £900-£1,300 | £1,100 |
| With in-built cylinder | 12kW | £1,500-£2,500 | £2,000 |
| Wall-mounted with cylinder | 3-15kW | £1,750-£2,000 | £1,875 |
| Floor-standing with cylinder and long warranty | 10-18kW | £2,350-£4,500 | £3,425 |
(Source: Checkatrade)
Electric combi boilers are a more compact, quieter, and cheaper alternative to gas boilers, as there is no gas waste pipe (flue). Most units offer at least 99% efficiency, meaning they are also better for the environment and reduce heat wastage.
UK boiler statistics reveal that, based on a national average of £0.28 per kWh, running a standard 12kW electric boiler at 70 hours per month will cost £235. By contrast, a gas boiler would cost £90 a month.
How much does a new oil boiler cost?
If your home is not connected to a main gas or electric network, an oil combi boiler can provide a good alternative for heating your property.
The price can range anywhere between £3,000 and £3,700, depending on which type you install. At the lower end of the scale, a heat-only oil boiler will set you back anywhere between £1,200 and £2,450, whereas an oil combi boiler can range from £2,000 to just above £2,800.
A breakdown of the cost differences for different types of oil boiler in the UK
| Type of oil boiler | Cost range | Installation cost range | Average total cost |
|---|---|---|---|
| Heat-only | £1,200-£2,450 | £500-£2,000 | £3,075 |
| System | £1,450-£2,375 | £500-£2,000 | £3,163 |
| Combi | £2,025-£2,825 | £500-£2,000 | £3,675 |
(Source: Checkatrade)
Installation costs for all three types of oil boiler can vary from £500 up to £2,000—you’ll need to factor in the cost of supplying heating oil too. Over the last 12 months, the price has fluctuated from highs of 97.9p/litre in November 2022, to around 59.1p/litre in June 2023. As of September 2023, the average price of supply heating oil stood at around 79.8p/litre.
How much does a new system boiler cost?
A system boiler is the opposite of a combi boiler, in that they supply your house with central heating while storing hot water for domestic use in a cylinder.
Recent UK boiler facts suggest the cost of a new system boiler starts at around £1,600 (inc. VAT) for a basic five-year warranty model, rising to £2,500 for a high-end system.
Should you opt to install a new gas system boiler, this will set you back around £2,700, while a typical oil alternative will cost £3,163. The average cost for a new electric system boiler (supply only) is around £1,200.
How much does a biomass boiler cost?
A biomass boiler uses sustainably-sourced wood as its source of fuel.
According to the latest UK boiler stats, you can expect to spend somewhere between £5,000 for a small, domestic biomass boiler, compared to £20,000 for a larger, commercial one, with the average price tag sitting around £10,000 (inc. VAT).
Due to the high initial costs of purchasing and installing a biomass boiler (averaging around £16,000 in total), the UK Government is currently offering significant rebates, by way of funding, in order to reduce the running costs, which works out at 4.11p/kWh.
In terms of fuel costs, a biomass boiler will set you back around £100 per tonne for wood chips, £99 per tonne for wood logs, and £200 per tonne for wood pellets.
How much does a new condensing boiler cost?
Condensing boilers are up to 90% more efficient than standard domestic boiler systems, thus making them some of the most energy-efficient options on the market.
A new condensing boiler cost normally averages at around £2,500 (exc. VAT). However, installation costs can vary based on your domestic circumstances and the type of boiler you choose.
Condensing boilers come in two varieties:
Regular - comes with a hot water tank and can supply heating to a large house.
Combi - doesn’t come with a water tank and is more suited to smaller houses and/or flats.
If you are replacing a regular condensing boiler with another regular model, the installation cost averages about £800. However, if you are switching from regular to combi, then this can cause the cost to almost double (around £1,550), according to the latest boiler facts.
How much does a new conventional boiler cost?
Conventional boilers heat previously-stored water until it’s ready to be used. This can be a viable option for larger homes that are more energy-intensive.
The cost of a small conventional boiler starts at around £480. However, the size you require will depend on how big your home is, and how much money you have to spend.
Boiler conversion costs UK
Those with an old, outdated, inefficient boiler may choose to upgrade to a better model and system. The associated conversion costs are broadly in line with installing a new boiler, including:
Regular to combi: £3,500
System to combi: £2,650
Back boiler to combi: £4,000.
Boilers and cost-related savings
Combi boilers run most efficiently with a flow temperature of 60°C or below. However, in reality, they’re often set much higher than that. This method of cost-saving is different to changing the thermostat temperature, which helps save energy by lowering the overall room temperature.
Knowledge surrounding boiler flow temperature appears limited among the UK population. A 2022 ONS survey revealed that only one in 10 people had lowered their flow temperature within the last year, compared to six in 10 who had lowered their thermostat.
How much could be saved by changing the flow temperature of your boiler?
UK boiler statistics suggest that reducing your boiler’s flow temperature to 60°C or less can vary considerably, depending on the source and study.
Nesta estimates that changing the settings on a standard, domestic combi boiler could save around £112 a year on energy bills for the average UK household
Cambridge Architectural Research (CAR) found typical savings of around £64 per household per year. This was a greater saving in comparison to installing a smart thermostat, as well as other free measures such as closing curtains at night (saving £10 per year), and placing foil behind radiators (saving £3-11 per year)
A study by Salford University found that by reducing the flow temperature from 80℃ to 60℃, this reduced total gas consumption by up to 9%, saving around £112 a year for the average UK household.
If 10 million UK households with combi boilers reset their flow temperature to 60℃ or below, this would cut £1 billion from energy bills, and save 1.7 million tonnes of CO(2). This is roughly the same as six million transatlantic flights. Financially, this could save the UK Treasury £500 million a year.
What additional changes can be made to your boiler in order to save money on your energy bills?
A breakdown of annual bill savings per UK household by different energy-saving methods
| Measure | Total UK energy savings (TWh/year) | Total UK energy bill savings (£bn/year) | Percentage of dwellings that could adopt this measure (%) | Percentage bill saving per household (%) |
|---|---|---|---|---|
| Lowering the setting on thermostatic radiator valves | 13.8 | 1.5 | 76 | 5.5 |
| Turn down the boiler flow temperature on combi boilers to 60℃ | 10.1 | 1 | 38 | 8 |
| Turn down how water temperature on combi boilers to 42℃ | 4.1 | 0.4 | 58 | 2.1 |
| Reduce hot water cylinder temperature to 60℃ | 1.6 | 0.2 | 25 | 2 |
| Turn off preheat on combi boilers | 0.6 | 0.1 | 23 | 0.8 |
(Source: Nesta)
According to research by Nesta, the most cost-effective method for UK households is to turn the flow temperature of their boiler down to 60℃. This would save around £97 a year, roughly 8% of total domestic energy costs.
This is followed by a saving of £68 a year (5.5% of the total energy bill for UK households) by lowering the setting on the thermostat valves.
Controlling your energy costs within the home is easier today more than ever. Customers can save up to £26 a year just by turning down the water temperature on their combi boilers, and/or reducing the water cylinder temperature to 60℃. In addition, turning off the preheat setting on a combi boiler can also reduce annual energy bills by £10.
The energy price cap
The energy price cap is a limit imposed by Ofgem on the amount domestic energy suppliers can charge customers on their standard tariffs. The cap typically changes throughout the year to reflect the price of wholesale energy, meaning higher wholesale energy costs usually result in a higher price cap.
Due to the rising price of gas and electricity in 2022, the UK Government brought in an Energy Price Guarantee (EPG) in October of that year to provide UK residents with some much-needed reassurance and relief going into the winter.
The guarantee ensured customers would not pay more than £2,500 for their household energy bill – regardless of how high the price cap was set – with the government subsidising anything above this threshold. However, the fall in wholesale energy prices throughout 2023 meant that the EPG wasn’t needed in the second half of the year.
The energy price cap for October-December 2023 has been set at £1,834 – a drop from £1,976 in July-September 2023. The maximum unit price for UK households has been set to 27p per kWh for electricity, and 7p per kWh for gas.
A breakdown of measures taken by UK residents to reduce their energy bills in 2022
In an effort to stay warm over the winter, more than two-thirds (67%) of people surveyed by Nesta said they would be wearing warmer clothes, as opposed to turning the heating on. This is followed by 57% who claimed they would reduce the number of hours per day the heating was on, plus just over half (51%) who said they would close the curtains to reduce heat loss.
Boiler efficiency in the UK
Heating and hot water accounts for more than 50% of our annual domestic energy bills, so having an efficient boiler can make a big difference to your costs.
Modern boiler systems that have been looked after with regular boiler maintenance burn their fuel more efficiently than old models that have been neglected. Looking after your boiler on a regular basis will also reduce the risk of gas leaks, and improve protection within your home (including carbon monoxide safety).
However, all systems will lose a degree of heat in the hot gases that escape from the flue pipe, and no system is completely 100% efficient—yet.
Condensing boilers tend to be the most energy-efficient option, as they recover heat from the flue gas, and use this to heat the central heating water.
Gas boiler efficiency statistics
If you have a mains gas connection, a modern, condensing boiler has, on average, the lowest running costs in providing heating and hot water to your home.
According to the Energy Saving Trust, gas is the cheapest fuel for heating your home across most of the UK, costing 6.9p/kWh on average in England, Scotland, and Wales. However, it's a different story in Northern Ireland, where gas typically costs 12p/kWh - almost double the price of the UK. Instead, coal is the cheapest fuel to heat a home in Northern Ireland, at 6.2p/kWh - nearly 3p cheaper than the average cost across the rest of the UK.
A breakdown of average UK electricity prices between different types of boiler
| Fuel/method of heating | Average price (pence/kWh) | Average price (pence/kWh) | Standing charge (£/year) | Standing charge (£/year) | CO2 equivalent factor (kgCO2e/kWh) | CO2 equivalent factor (kgCO2e/kWh) |
|---|---|---|---|---|---|---|
| England, Wales, and Scotland | Northern Ireland | England, Wales, and Scotland | Northern Ireland | England, Wales, and Scotland | Northern Ireland | |
| Gas | 6.9 | 12.3 | 108.11 | - | 0.213 | 0.213 |
| Oil | 9 | 6.9 | - | - | 0.298 | 0.298 |
| LPG | 8.7 | 11.3 | 63 | 63 | 0.24 | 0.24 |
| Wood pellet | 13.8 | 9.1 | - | - | 0.048 | 0.048 |
Prices for gas and electricity are based on the average supplier tariffs, as of October 2022, and discounted further according to the Government’s Energy Bill Relief Scheme. Oil prices are based on the average cost for a 1,000 litre purchase, as of October 2022.
| Fuel/method of heating | Average price (pence/kWh) | Average price (pence/kWh) | Standing charge (£/year) | Standing charge (£/year) | CO2 equivalent factor (kgCO2e/kWh) | CO2 equivalent factor (kgCO2e/kWh) |
|---|---|---|---|---|---|---|
| England, Wales, and Scotland | Northern Ireland | England, Wales, and Scotland | Northern Ireland | England, Wales, and Scotland | Northern Ireland | |
| Coal/solid fuel | 8.9 | 6.2 | - | - | 0.404 | 0.404 |
| Electricity (off peak economy 7) | 16.35 | 8.7 | 194.76 | 36.89 | 0.225 | 0.234 |
| Electricity (on peak economy 7) | 33.44 | 16.4 | - | - | 0.225 | 0.234 |
| Electricity (standard rate) | 27.35 | 16.4 | 194.8 | 36.89 | 0.225 | 0.234 |
(Source: Energy Saving Trust)
In terms of the method of heating, an on-peak Economy 7 electric boiler is the most expensive option, costing almost 33.44p/kWh across England, Scotland, and Wales. In Northern Ireland, it's just 16.4p/kWh."
Across Great Britain, the standing charge for an LPG boiler is around £63 a year, compared to £108.60 a year for gas in England, Scotland, and Wales. In Northern Ireland, there’s a yearly standing charge of about £37 for using either a standard electric boiler or an off-peak Economy 7 electric boiler.
Coal produces the most carbon emissions, at just 0.4kgCO2e/kWh. This is around double the amount compared to a gas boiler, which emits only 0.213kgCO2e/kWh.
Cost savings through improved gas boiler efficiency
While there will be an initial outlay in replacing an old, inefficient boiler with a newer, more efficient model, it will ultimately help to reduce your energy bills in the long run.
Older gas boilers can have an efficiency of less than 50%, whilst the new, condensing boilers on the market should exceed 90%.
With an old, G-rated boiler, up to 40% of the money you spend is wasted. In real terms, for every £1,000 you spend on gas, £400 is essentially thrown out the window (or roof, or door).
According to estimates from recent UK boiler statistics, improving gas boiler efficiency in your home could recuperate up to £800 over the resulting 12 months.
The length of time it takes to recoup the cost of the boiler will depend on how much your new boiler costs, divided by the annual savings it provides. For example, if you spend £4,000 (the average cost of a new boiler in the UK), and it reduces your energy bill by £400 a year, it will take 10 years to pay for itself.
The tariff you are on will also affect your potential savings. For example, if you have an Economy 7 tariff, then this means rates are cheaper during the night, but can be more expensive during the day compared to a standard tariff.
Or, you may opt for an Economy 10 tariff, which increases the off-peak rate to 10 hours a day. This is usually broken down to seven hours at night, and three hours during the day. But again, standard charges are usually higher.
A breakdown of average annual savings by upgrading inefficient boilers to an A-rated boiler in different types of UK properties
| Old boiler rating D (78-82%) | Old boiler rating D (78-82%) | Old boiler rating E (74-78%) | Old boiler rating E (74-78%) | Old boiler rating F (70-74%) | Old boiler rating F (70-74%) | Old boiler rating G (<70%) | Old boiler rating G (<70%) | |
|---|---|---|---|---|---|---|---|---|
| Housing type | GB | N.Ireland | GB | N.Ireland | GB | N.Ireland | GB | N.Ireland |
| Detached bungalow | £180 | £145 | £200 | £185 | £225 | £235 | £320 | £330 |
| Detached house | £245 | £280 | £300 | £350 | £380 | £435 | £540 | £600 |
| Mid-floor flat | £75 | £55 | £80 | £75 | £95 | £95 | £135 | £140 |
| Semi-detached house | £200 | £160 | £225 | £210 | £250 | £260 | £355 | £365 |
| Mid-terraced house | £165 | £135 | £185 | £170 | £205 | £215 | £295 | £305 |
(Source: Energy Saving Trust)
The table above shows how much you could save on your annual energy bills in the UK if you exchanged your old boiler for a newer, A-rated model. However, the amount of associated savings varies depending on the type of property you live in.
If you live in a detached house in England, Scotland, or Wales, you can expect average savings of £245 a year on your energy bills, just by upgrading from a D-rated boiler to an A-rated one. This comparable figure drops to £75/year for a mid-floor flat.
There is an even greater gulf in Northern Ireland, with savings of £280 a year on average for a detached house, compared to £55 a year for a mid-floor flat.
By upgrading from an E-rated boiler, detached houses in most of the UK can expect savings of £300-£350 a year on their fuel bills, down to £75-£80 per year for mid-floor flats.
F-rated boilers typically operate on 70-74% efficiency, meaning up to 30% of the heat generated is lost through the system. By replacing this with a new, A-rated system, the cost savings for different property types can be up to:
£380-£435 for detached housing
£250-£260 for semi-detached houses
£225-£235 for detached bungalows
£205-£215 for mid-terraced housing
£95 for mid-floor flats.
A breakdown of potential savings of changing an F-rated boiler to an A-rated boiler for different property types in the UK
The least-efficient boiler types are G-rated systems, with an efficiency of less than 70%. UK detached houses could reduce their energy bills by between £500 and £600 a year, by upgrading to an A-rated condensing boiler. This is around 70% more savings than detached bungalows and 80% more than mid-terraced housing.
Mid-floor flats can also save around £125-135 a year, just by installing a new, A-rated boiler system.
UK boiler efficiency ratings
In a bid to understand boiler efficiency patterns in the UK, comparison experts at Uswitch collated a number of key metrics for boilers across the country.
We compared the boiler metrics by town/city, region, property type, and property age, to uncover the main trends in UK boiler efficiency ratings.
Our data looked at hot water efficiency, hot water cost, heating efficiency, and heating cost to give an overall average score out of 10 for each local authority across the UK.
Boiler efficiency comparison across the UK
A breakdown of boiler efficiency ratings across the UK
| Local authority | Number of certificates | Average hot water efficiency | Average hot water annual cost (£) | Average heating efficiency | Average heating annual cost (£) | Final boiler score |
|---|---|---|---|---|---|---|
| Hammersmith and Fulham | 48,227 | 3.949 | 105.5 | 4.003 | 565.28 | 9.94 |
| Wandsworth | 75,906 | 3.921 | 108.63 | 4.003 | 596.03 | 9.79 |
| City of London | 984 | 3.917 | 99.71 | 4.004 | 375.65 | 9.76 |
| Isle of Anglesey | 9,948 | 3.924 | 111.07 | 4.003 | 662.12 | 9.76 |
| Lambeth | 76,987 | 3.92 | 106.38 | 4.003 | 559.5 | 9.76 |
| Westminster | 47,002 | 3.919 | 109.75 | 4.003 | 567.28 | 9.72 |
| Glasgow City | 138,094 | 3.935 | 105.64 | 4 | 538 | 9.7 |
| Mid-Suffolk | 12,992 | 3.912 | 112.43 | 4.003 | 507.68 | 9.62 |
| West Dunbartonshire | 22,139 | 3.931 | 104.63 | 4 | 584.86 | 9.58 |
| Kensington and Chelsea | 39,079 | 3.903 | 113.9 | 4.003 | 665.22 | 9.57 |
(Source: Uswitch, via DLUHC and Scottish Government)
According to our UK boiler stats, London is home to some of the most efficient boilers in the UK. Hammersmith and Fulham topped the list, with high scores for average hot water efficiency and average hot water annual cost contributing to a final score of 9.69.
The inner London borough was followed by three more London areas, with Wandsworth finishing second with a score of 9.79, and the City of London and Lambeth finishing joint third with scores of 9.76. These two London boroughs also shared the third spot with Wales’s Isle of Anglesey.
London was responsible for another three entries in the top 10, meaning that the English capital accounted for 60% of the UK’s most efficient boiler areas.
There are numerous factors that may have contributed to London’s prevalence in our boiler efficiency ratings, including:
The capital’s typically warmer weather will likely mean that its boilers are under less strain than colder locations further north.
London has a notoriously high rate of people renting properties, with a report from Boiler Guide suggesting that London had the lowest homeowner rate of any UK region (37.2%). Many landlords may opt to service and update boilers more regularly than people typically would in their own homes.
Of all the places covered in our study, the City of London was found to have the lowest average heating costs per year at just £375.65, as well as the lowest annual water costs (£99.71).
| Local authority | Number of certificates | Average hot water efficiency | Average hot water annual cost (£) | Average heating efficiency | Average heating annual cost (£) | Final boiler score |
|---|---|---|---|---|---|---|
| Castle Point | 17,317 | 3.701 | 135.18 | 3.99 | 749.28 | 0.06 |
| Eilean Siar | 324 | 3.475 | 154.72 | 3.991 | 1,017.75 | 0.06 |
| Gedling | 28,633 | 3.718 | 127.23 | 3.993 | 709.91 | 0.23 |
| Melton | 10,018 | 3.743 | 130.49 | 3.992 | 738.31 | 0.25 |
| Oadby and Wigston | 12,988 | 3.718 | 131.7 | 3.994 | 716.07 | 0.36 |
| Swansea | 55,036 | 3.696 | 129.74 | 3.994 | 668.64 | 0.37 |
| Blackpool | 43,803 | 3.75 | 125.32 | 3.994 | 804.59 | 0.49 |
| Broxtowe | 24,242 | 3.707 | 127.29 | 3.995 | 720.64 | 0.54 |
| Carmarthenshire | 28,250 | 3.725 | 128.17 | 3.995 | 732.69 | 0.54 |
| Wyre | 27824 | 3.76 | 124.23 | 3.994 | 724.81 | 0.55 |
(Source: Uswitch via DLUHC and Scottish Government)
The bottom place in our boiler efficiency table is shared by Castle Point in Essex, and the Scottish town Eilian Siar. Both places recorded final scores of 0.06, with Eilian Siar’s average annual heating cost of £1017.75—the highest of all the 369 local authorities in our study.
Eilian Siar was also found to have the highest water costs, with its average cost of £154.72 per year (over £19 more than Castle Point—the next costliest place).
A string of low-efficiency scores were found in the East Midlands, with two places each from the counties of Leicestershire and Nottinghamshire finishing in our bottom 10. Of these counties, the Nottinghamshire local authority of Gedling obtained the lowest score, with its average heating efficiency score of 3.99 contributing to a rating of 0.23 out of 10.
Regional boiler efficiency comparison across the UK
A breakdown of regional boiler efficiency ratings in the UK 2022
| Region | Number of certificates | Average hot water efficiency | Average hot water annual cost (£) | Average heating efficiency | Average heating annual cost (£) | Final boiler score |
|---|---|---|---|---|---|---|
| London | 1,775,735 | 3.882 | 113.81 | 4 | 604.59 | 9.17 |
| Scotland | 880,921 | 3.879 | 114.05 | 3.999 | 667.33 | 7.92 |
| South West | 1,111,659 | 3.879 | 115.35 | 3.998 | 603.87 | 7.08 |
| West Midlands | 1,292,337 | 3.841 | 117.44 | 3.998 | 677.97 | 6.25 |
| South East | 1,956,553 | 3.861 | 121.06 | 3.997 | 619.19 | 5.84 |
| North East | 741,692 | 3.821 | 116.17 | 3.998 | 682.16 | 5 |
| Yorkshire and The Humber | 1,339,071 | 3.85 | 115.25 | 3.997 | 745.01 | 5 |
| East of England | 1,268,245 | 3.827 | 121.83 | 3.997 | 618.85 | 3.34 |
| Wales | 673,569 | 3.808 | 119.37 | 3.997 | 669.83 | 2.5 |
| North West | 1,819,737 | 3.817 | 118.44 | 3.996 | 706.28 | 2.09 |
| East Midlands | 1,101,336 | 3.79 | 121.73 | 3.996 | 670.77 | 0.83 |
(Source: Uswitch via DLUHC and Scottish Government)
Our regional data further validates the evidence of high boiler efficiency in London. With the lowest average annual water cost of £113.81, London’s final score of 9.17 out of 10 suggests that its dominance across all UK local authorities was no anomaly.
London was followed by Scotland, with a solid overall score of 7.92, suggesting that Eilean Siar’s position, as the joint, least-efficient local authority in the country, was the exception rather than the rule.
The high presence of East Midlands places in our previous list was given further weight by the county’s position in our regional study. With the lowest score for water efficiency and joint-lowest score for heating efficiency, the East Midlands finished bottom with a score of 0.83 out of 10.
The South West's average heating cost of £603.87 per year was the lowest in our regional study.
Boiler efficiency comparison by type of property
| Property type | Number of certificates | Average hot water efficiency | Average hot water annual cost (£) | Average heating efficiency | Average heating annual cost (£) | Final boiler score |
|---|---|---|---|---|---|---|
| Bungalow | 1,229,681 | 3.798 | 120.18 | 3.994 | 679.76 | 2 |
| Flat | 2,878,135 | 3.939 | 96.43 | 4 | 402.97 | 8 |
| House | 9,736,369 | 3.823 | 123.83 | 3.997 | 730.73 | 4 |
| Maisonette | 311,281 | 3.91 | 107.69 | 4 | 535.94 | 6 |
(Source: Uswitch via DLUHC and Scottish Government)
When it comes to boiler efficiency by property, flats were found to have the most efficient boilers. As flats are typically smaller and have fewer occupants than houses, it’s only natural that their boilers require less hot water and energy outlay to run effectively.
Nevertheless, the modest average heating costs of under £403 per year, and final score of eight out of 10, are indicative of the generally high efficiency of boilers in UK flats.
Maisonettes received the next highest score, with an average water cost of £107.69 contributing to a rating of six out of 10. Maisonettes were followed by houses, which were found to have the highest average heating costs per year at £730.73. With average water costs of £123.83 per year, houses were also found to be the most costly property type when it comes to water bills.
Bungalows were found to have the worst heating efficiency of all home types in our study. Despite being typically smaller than most houses, bungalows' low ratings for heating efficiency and hot water efficiency resulted in a score of two out of 10.
Boiler efficiency comparison by type of house
A breakdown of boiler efficiency ratings by property type in the UK 2022
| Type of house | Number of certificates | Average hot water efficiency | Average hot water annual cost (£) | Average heating efficiency | Average heating annual cost (£) | Final boiler score |
|---|---|---|---|---|---|---|
| Enclosed end-terrace | 132,417 | 3.914 | 100.14 | 4 | 449.67 | 7.86 |
| Enclosed mid-terrace | 90,179 | 3.903 | 102.67 | 4.001 | 515.17 | 7.86 |
| End-terrace | 2,095,514 | 3.881 | 110.73 | 3.999 | 600.5 | 5.71 |
| Mid-terrace | 3,995,863 | 3.866 | 113.39 | 3.999 | 602.79 | 4.29 |
| Semi-detached | 4,804,107 | 3.822 | 118.95 | 3.997 | 648.71 | 2.86 |
| Detached | 2,900,777 | 3.82 | 128.68 | 3.995 | 809.55 | 1.43 |
(Source: Uswitch via DLUHC and Scottish Government)
In our study on boiler efficiency by house type, enclosed end-terraced and enclosed mid-terrace houses shared first-place with scores of 7.86 out of 10.
While the average annual heating cost of enclosed end terraces (£449.67) was the lowest in our study, these UK boiler statistics show enclosed mid-terraces to have slightly lower water costs, resulting in the two house types achieving the same scores.
At the other end of the scale were detached houses and semi-detached houses. With an average heating cost of £809.55 per year, detached houses finished bottom with an overall score of 1.43 out of 10.
Boiler efficiency comparison by property age
A breakdown of boiler efficiency ratings for different property ages in the UK 2022
| Property age | Number of certificates | Average hot water efficiency | Average hot water annual cost (£) | Average heating efficiency | Average heating annual cost (£) | Final boiler score |
|---|---|---|---|---|---|---|
| 2007-2011 | 150,581 | 4.02 | 93.79 | 4.001 | 327.27 | 8.85 |
| 2012 onwards | 93,918 | 4.029 | 92.49 | 4 | 328.77 | 8.08 |
| 2003-2006 | 349,874 | 3.947 | 112.56 | 4 | 416.22 | 8.08 |
| 1996-2002 | 544,846 | 3.864 | 128.61 | 4 | 564.25 | 7.31 |
| 1900-1929 | 2,018,149 | 3.85 | 117.16 | 3.997 | 848.85 | 5.39 |
| before 1900 | 1,111,452 | 3.848 | 118.36 | 3.997 | 964.84 | 4.62 |
| 1930-1949 | 1,897,780 | 3.8 | 124.32 | 3.996 | 772.88 | 3.85 |
| 1983-1990 | 667,018 | 3.768 | 124.24 | 3.999 | 562.11 | 3.46 |
| 1991-1995 | 418,431 | 3.767 | 126.83 | 4 | 585.43 | 3.46 |
| 1950-1966 | 2,287,424 | 3.786 | 124.36 | 3.996 | 660.68 | 2.7 |
| 1976-1982 | 688,228 | 3.779 | 124.75 | 3.996 | 561.94 | 2.7 |
| 1967-1975 | 1,430,472 | 3.772 | 126.3 | 3.993 | 637.76 | 1.54 |
(Source: Uswitch, via DLUHC and Scottish Government)
With a study lowest average annual heating cost of £327.27, properties built between 2007 and 2011 topped our list with a final score of 8.85 out of 10. These homes were followed by properties built from 2012 onwards, which had the lowest average water costs per year (£92.49).
In fifth place were houses built between 1900 and 1929, with average heating costs of £848.85 per year. These homes were followed by houses built prior to 1900, which finished sixth with average water costs of £118.36.
Beneath properties built during these eras were an array of more recently built homes, including those built between 1991-1995, which had the highest average annual water bills in our study (£126.83).
Of all the properties in our study, homes built from 1967-1975 finished bottom of our list with a final score of 1.54. Houses built in this period had by far the highest annual heating costs, with an average price of £637.76 per year.
The findings indicate a substantial decline in the heating efficiency of homes built post-1929 that appears to peak in the late 60s and early 70s.
Based on our evidence, it seems that it took until the mid-to-late nineties before UK homes were consistently built in a way that was more boiler-efficient than homes built before 1929.
Boiler efficiency comparison by property occupancy
| Property tenure | Number of certificates | Average hot water efficiency | Average hot water annual cost (£) | Average heating efficiency | Average heating annual cost (£) | Final boiler score |
|---|---|---|---|---|---|---|
| Rented (social) | 2505962 | 3.921 | 105.26 | 4 | 477.62 | 7.5 |
| Rented (private) | 2389729 | 3.873 | 111.23 | 3.999 | 628.9 | 5 |
| Owner-occupied | 7860305 | 3.784 | 128.33 | 3.996 | 776.71 | 2.5 |
(Source: Uswitch, via DLUHC and Scottish Government)
Our final study looked at the boiler efficiency based on the type of occupant residing in a property. We can reveal that socially rented properties have the most efficient boilers, with average annual water costs of £105.25, and heating costs of £447.62, both contributing to a final score of 7.5 out of 10.
Owner-occupied properties had the lowest scores on the list, with an average annual heating cost of over £776, contributing to a rating of 2.5 out of 10.
UK Boiler Upgrade Scheme statistics 2023
One major change in 2022 was the adjustment to Building Regulations, where any new-build properties are required to have a 31% reduction in their carbon footprint.
In order to meet the UK Government’s target of net zero emissions by 2050, virtually all heating in buildings will need to be decarbonised.
The Boiler Upgrade Scheme (BUS) 2022 aims to incentivise and increase the amount of low-carbon heating technologies, by providing energy efficiency grants. These can be used to install air source heating pumps (ASHP), ground source heat pumps (GSHP), and in some cases, a biomass boiler.
Grants range from £5,000 for an ASHP or biomass boiler, up to £6,000 for a GSHP.
Aims of the Boiler Upgrade Scheme (BUS) 2022
The Boiler Upgrade Scheme (BUS) was launched on 1 April 2022 and has approved funding up until 2025.
It’s being administered by Ofgem, and has three main objectives:
Increase the amount of low-carbon heating systems in homes, and small, non-domestic buildings, across England and Wales with up to 90,000 installations between 2022 and 2025.
Continue to decarbonise UK heating systems by delivering up to 1.1MtCO2e of carbon savings over Carbon Budgets 4 and 5, and 2.6MtCO2e over its lifetime.
Expand the existing low-carbon heat market and supply chain, by creating an average of 2,100 direct full-time equivalents (FTE) and 1,800 indirect FTE jobs per year between 2022-25.
The BUS scheme is an installer-led scheme, meaning the person looking to install low-carbon technology has to submit a voucher application.
Vouchers are issued by Ofgem on a first-come, first-served basis to applicants who meet the eligibility criteria, and until the budget cap for the financial year is reached. ASHP and biomass boiler vouchers are valid for three months, while GSHP vouchers will last for six months.
A breakdown of voucher applications for the UK Boiler Upgrade Scheme (BUS) 2023
According to UK boiler statistics from Ofgem, more than 18,400 applications were received by residents of England and Wales for BUS vouchers between May 2022 and May 2023. The vast majority (96%) of these were for air source heat pumps (ASHPs). Of these applications, nearly 87% were successful, resulting in almost 15,500 vouchers being issued.
More than three-quarters (77%) of these vouchers were redeemed by May 2023, of which 97% have been paid back to the applicant. This means that, of the original 17,682 applications for ASHPs, almost two-thirds (64%) were successfully installed and redeemed between May 2022 and May 2023.
By contrast, 558 voucher applications for ground source heat pumps (GSHPs) and 193 for biomass boilers were received in the same time period. As of May 2023, the success rates for installation and redemption of these technologies stood at 54% and 69%, respectively.
A breakdown of voucher applications for the UK Boiler Upgrade Scheme 2023 by type of application
Of all applications received between May 2022 and May 2023 for boiler upgrade scheme vouchers, 94% were from residents of England, and 6% were from Wales.
96% of those received from English households applied for vouchers to install an air source heat pump compared to 90% of Welsh applications.
By contrast, there were over 10 times more ground source heat pump applications received from England compared to Wales (515 vs 43), and around 64% more for biomass boilers (120 vs 73). Yet, as a percentage of total applications, this equates to less than 1% for England, but over 7% for Wales.
A breakdown of voucher applications for the UK Boiler Upgrade Scheme 2023 by region
Regionally, the South West and South East both had over 3,400 applications for the BUS between May 2022 and May 2023 – the highest of any regions in England and Wales. Combined, these two regions accounted for more than two-fifths (41%) of total applications during this period.
98% of applications from the South East were for air source heat pumps, compared to 94% for the South West. However, there were more than double voucher requests for ground source heat pumps in the South West compared to the South East (77 vs 63, respectively), and 41 for biomass boilers compared to just two in the South East.
Applications for ground source heat pumps were also relatively common in Yorkshire and the Humber, with 61 received between May 2022 and May 2023. This represented just over 3% of the total voucher applications from this region.
Biomass boiler voucher applications were most common in the South West (41) followed by the North East (25), the latter of which represented 5% of their total application numbers.
A breakdown of different options on the UK Boiler Upgrade Scheme 2023 by the cost of installation
According to the latest UK boiler statistics, of the three technologies available through the boiler upgrade scheme (BUS), ground source heat pumps are the most expensive to install. On average, these cost between £17,579 and £34,900.
The median value for installing a ground source heat pump stands at £24,000 – more than 50% higher than the median cost of a biomass boiler, and around £11,000 more expensive than air source heat pumps. Installation costs for air source heat pumps fall somewhere between £10,870 and £15,422, with a median value of about £13,000.
A breakdown of different options on the UK Boiler Upgrade Scheme 2023 by the capacity of installation
Biomass boilers have the largest median capacity at 23kW – more than double that of ground source heat pumps (10kW) and 91% more than air source heat pumps (12kW). The range in capacity for biomass boilers falls between 18-25kW, compared to 10-16kW for ground source heat pumps and 8-12kW for air source heat pumps.
A breakdown of the number of redemptions on the UK Boiler Upgrade Scheme by type of fuel (2023)
In terms of redemptions paid between May 2022 and May 2023, almost half (48%) were for gas-driven air source heat pumps , followed by 25% for oil-powered ASHPs.
Of the 292 ground source heat pumps redeemed this year, 161 displaced no fuel, 69 were oil, and 38 were gas. By comparison, of the 133 biomass boilers authorised for installation, 79 were driven by oil, 22 for direct electricity, and just 11 for liquified petroleum gas (LPG).
A breakdown of the total number of redemptions approved on the boiler upgrade scheme by type of boiler (2023)
| Type of property | Air source heat pumps: Number | Ground source heat pumps: Number | Shared ground loop round source heat pumps: Number | Biomass boilers: Number | All technology types: Number |
|---|---|---|---|---|---|
| Domestic | 11,233 | 289 | 9 | 133 | 11,664 |
| Non-domestic | 49 | 4 | 0 | 0 | 53 |
| Unknown | 2 | 0 | 0 | 0 | 2 |
| Total | 11,284 | 293 | 9 | 133 | 11,719 |
(Source: Ofgem and Microgeneration Certification Scheme (MCS) Installation Database, via the Department for Business, Energy, and Industrial Strategy)
Of the 11,719 redemptions approved for the boiler upgrade scheme (BUS) between May 2022 and May 2023, virtually all (99.5%) were for domestic properties. Over 11,200 of these (96%) were for air source heat pumps, with 289 for ground source heat pumps, and 133 for biomass boilers.
Of the 53 authorised upgrades for non-domestic properties, 49 (93%) were for air source heat pumps, and just four (8%) were for a ground source heat pump.
A breakdown of the UK Boiler Upgrade Scheme 2023 by the number of applications throughout the year
The number of voucher applications for the boiler upgrade scheme (BUS) fluctuated between May 2022 and May 2023, with just over 1,100 in May 2022, up to a peak of 1,666 in November. Issued vouchers, on the other hand, fluctuated throughout the year, beginning at just 17 in May 2022 before peaking at 2,098 in July 2022. Since then, numbers fluctuated between 1,200 and 1,600 over the following 10 months.
Alongside this, redemption applications for the BUS increased from 175 in May 2022 to a peak of 1,156 in January 2023. Things would settle after that, fluctuating between 900 and 1,100 from January to May 2023.
Paid redemptions also grew rapidly in the same period, from just seven in May 2020 to a high of 1,394 in December. Between January 2023 and May 2023, the number of paid redemptions per month ranged from 864 to 1,294.
Best boiler brands in the UK 2023
A new Uswitch study identified the best boiler brands in the UK, based on the number of negative reviews and type of customer complaints within the last 12 months.
This study involved collating data for different companies via TrustPilot, and categorising them based on issues relating to:
Customer service
Engineers
Broken boilers
Boiler servicing
Getting appointments
Controls/thermostats
Installation.
Finally, the percentage of negative reviews were calculated, both as a percentage of the total negative reviews, as well as the total overall reviews within the last year.
The five companies with the lowest percentage of negative reviews were:
Valliant
Ideal Heating
Alpha Innovation
Baxi
Worcester Bosch
A breakdown of negative reviews for different UK boiler companies
| Boiler company | Total reviews last 12 months | Number of non-5-star reviews last 12 months | Negative review % |
|---|---|---|---|
| Vaillant | 1842 | 157 | 8.52 |
| Viessmann | 1189 | 367 | 30.87 |
| Glow-Worm | 667 | 135 | 20.24 |
| Baxi | 10647 | 1876 | 17.62 |
| Alpha Innovation | 1720 | 283 | 16.45 |
| Ideal Heating | 12299 | 1051 | 8.55 |
| Worcester Bosch | 7405 | 1497 | 20.22 |
(Source: Uswitch, via TrustPilot, NLTK, and Github)
UK boiler stats from our study reveal that, within the last 12 months, Vaillant and Ideal Heating had the fewest number of negative reviews, both with less than 9%. Ideal Heating had the most reviews in total (almost 12,300), of which over 1,000 had negative comments, compared to 367 from nearly 1,800 reviews for Vaillant.
At the other end of the scale, Viessmann had just short of 1,200 reviews within the last year, yet nearly a third of these (30.87%) contained negative comments.
A breakdown of reported customer issues for different UK boiler companies
| Boiler company | Customer service issues % | Issues with engineers % | Broken boilers % | Issues during boiler servicing % | Issues with appointments % | Controls/Thermostat issues % |
|---|---|---|---|---|---|---|
| Vaillant | 18.22 | 17.78 | 7.78 | 23.11 | 9.78 | 23.33 |
| Viessmann | 17.82 | 13.9 | 12.08 | 17.82 | 4.53 | 33.84 |
| Glow-Worm | 16.88 | 20.78 | 11.69 | 20.78 | 6.49 | 23.38 |
| Baxi | 14.76 | 27.23 | 4.53 | 20.14 | 12.64 | 20.71 |
| Alpha Innovation | 13.54 | 23.18 | 3.39 | 26.56 | 14.06 | 19.27 |
| Ideal Heating | 10.83 | 28.28 | 8.93 | 20.3 | 11.77 | 19.89 |
| Worcester Bosch | 8.28 | 20.61 | 14.85 | 14.85 | 7.98 | 33.43 |
(Source: Uswitch, via TrustPilot, NLTK, and Github)
When broken down by company, most customer grievances with Vaillant centre around boiler servicing and controls/thermostats (both 23%), whereas the corresponding figures for Viessmann and Worcester Bosch are around a third of their total negative comments.
Less than 8% of Vaillant’s negative feedback was regarding broken boilers, compared to nearly 15% for Worcester Bosch.
Stark contrasts are also seen between other companies. For example, 27% of Baxi’s customers reported issues with engineers within the last 12 months. The matching figure for Viessmann was around 14% (almost half). Baxi, on the other hand, scored better for broken boiler issues. Alongside Alpha Innovation, just 4% of their negative feedback related to this category.
8% of Worcester Bosch’s negative comments surrounded customer service, compared to 18% for Vaillant. By contrast, Glow-Worm scored better for appointment issues (around 6%), yet had almost a quarter of its feedback concerns centred around controls and thermostats.
A breakdown of UK boiler companies by the percentage of customer-reported issues
| Issue | Vaillant | Viessmann | Glow-Worm | Baxi | Alpha Innovation | Ideal Heating | Worcester Bosch |
|---|---|---|---|---|---|---|---|
| Customer service issues | 14.76 | 8.28 | 10.83 | 18.22 | 16.88 | 13.54 | 17.82 |
| Issues with engineers | 27.23 | 20.61 | 28.28 | 17.78 | 20.78 | 23.18 | 13.9 |
| Broken boilers | 4.53 | 14.85 | 8.93 | 7.78 | 11.69 | 3.39 | 12.08 |
| Issues during boiler servicing | 20.14 | 14.85 | 20.3 | 23.11 | 20.78 | 26.56 | 17.82 |
| Issues with appointments | 12.64 | 7.98 | 11.77 | 9.78 | 6.49 | 14.06 | 4.53 |
| Controls/Thermostat issues | 20.71 | 33.43 | 19.89 | 23.33 | 23.38 | 19.27 | 33.84 |
(Source: Uswitch, via TrustPilot, NLTK, and Github)
Controls and thermostat problems were the most commonly cited issue by customers, for the seven companies in our study. Up to a third of complaints were reported against Viessmann and Worcester Bosch for this category, down to just under a fifth for Glow-Worm and Ideal Heating.
Issues with engineers were also particularly high, with more than 20% for all companies, apart from Baxi (17.8%), and Worcester Bosch (13.9%). Similar could be said for boiler servicing issues, with more than a quarter attributed to Ideal Heating (nearly 27%) within the last year, compared to just under 15% for Viessmann.
Broken boilers had the fewest percentage of complaints, ranging from nearly 15% for Viessmann, down to low, single-figures for Ideal Heating (3.4%), Vaillant (4.5%), and Baxi (7.8%).
Reports of appointment issues were also low. 14% of these came from Ideal Heating, compared to less than 5% for Worcester Bosch, and almost 6.5% for Alpha Innovation.
A breakdown of UK boiler companies by reported customer issues as a percentage of total reviews
| Boiler company | Customer service issues % | Issues with engineers % | Broken boilers % | Issues during boiler servicing % | Issues with appointments % | Controls/Thermostat issues % |
|---|---|---|---|---|---|---|
| Vaillant | 1.55 | 1.52 | 0.66 | 1.97 | 0.83 | 1.99 |
| Viessmann | 5.5 | 4.29 | 3.73 | 5.5 | 1.4 | 10.44 |
| Glow-Worm | 3.42 | 4.21 | 2.37 | 4.21 | 1.31 | 4.73 |
| Baxi | 2.6 | 4.8 | 0.8 | 3.55 | 2.23 | 3.65 |
| Alpha Innovation | 2.23 | 3.81 | 0.56 | 4.37 | 2.31 | 3.17 |
| Ideal Heating | 0.93 | 2.42 | 0.76 | 1.73 | 1.01 | 1.7 |
| Worcester Bosch | 1.67 | 4.17 | 3 | 3 | 1.61 | 6.76 |
(Source: Uswitch, via TrustPilot, NLTK, and Github)
As a percentage of total reviews, the numbers look slightly more promising for the seven companies in our study.
Less than 2.5% of total reviews for Ideal Heating cited an issue with engineers—the most commonly reported issue faced by their customers—compared to less than 1% for broken boilers.
Vaillant also fared well in this analysis, with less than 2% across the board for all six categories, and less than 1% for broken boilers and appointment-related issues.
At the other end of the scale, over 10% of Viessmann’s total feedback comments were relating to controls and thermostat issues. This is contrasted by 5.5% for both customer service and boiler servicing—the largest percentage for these issues across all seven companies in the study (as a percentage of total reviews).
Boiler problems
A 2019 study from Boiler Guide found that London was the UK region with the highest percentage of boiler breakdowns between 2009-2019. UK boiler stats can reveal that more than 6% of boilers in the capital had broken down during this period.
London was followed on the boiler breakdown statistics list by the West Midlands at 6.04% and the North East at 5.59%.
Yorkshire was found to be the place in which boilers were least likely to break down, with an estimated 4.27% of boilers faltering during this period. The White Rose county was followed by Scotland and the North West at the bottom of the list, with scores of 4.38% and 4.79%, respectively.
A breakdown of the percentage of UK boiler breakdowns by region between 2009-2019
The study by Boiler Guide took into account the increased number of homes in regions like London and standardised the data to create a more accurate picture of the concentration of boiler problems across the UK.
With the average boiler life expectancy estimated to be between 10-15 years, there are numerous reasons that could explain London’s high boiler breakdown statistics, such as:
The higher concentration of older homes, and therefore older heating systems.
A large presence of listed buildings that aren’t allowed to update their heating systems.
Higher average temperatures than the north, thus requiring less boiler use.
Boiler inactivity over a long period of time can result in the system stagnating and eventually blocking, resulting in the need for repairs or replacements.
The data also points to London's higher rate of rental properties being a contributing factor in its elevated boiler breakdown statistics. A 2022 report by Birch and Co found that London had by far the lowest percentage of homeowners of any region in the UK (50.9%).
London was followed in this study by the North East, whose total of 60.8% was at least 4% lower than any other region bar London. The fact that these are the two regions with the highest and third-highest percentage of boiler breakages, respectively, suggests a potential link between rental properties and boiler breakdown prevalence.
A breakdown of the percentage of homeowners in the UK by region (2022)
| Region | Percentage of homeowners (%) |
|---|---|
| London | 50.90% |
| North East | 60.80% |
| West Midlands | 68.70% |
| Yorkshire and the Humber | 65.20% |
| East Midlands | 69.40% |
| East of England | 68.20% |
| South West | 67.70% |
| North West | 66.50% |
| South East | 68.50% |
(Source: Bird and Co)
A report from Boiler Guide found a clear link between hard water areas and boiler breakdown frequency. In fact, the top three regions for boiler breakdowns are all supplied with hard water, and the bottom three are soft water areas.
Common boiler problems
The presence of boiler problems can be attributable to a number of faults, with some of the most common boiler problems including:
Boiler leaks caused by excessive pressure, corroded pipes or tanks, or a faulty component
Combi boiler set to only heat water and not central heating
Low pressure
Kettling - when the boiler is heating water too quickly resulting in steaming and trapped air
Limescale buildup
Frozen condensate pipe caused by colder weather in the winter months
Thermostat issues.
Anyone experiencing these issues should contact a boiler repairs expert, to diagnose and resolve the problem as quickly and efficiently as possible.
A breakdown of reported boiler breakdown enquiries for each month of the year in the UK
According to a study by Boiler Guide, January was found to be the month with the highest percentage of boiler breakdown enquiries (15.56%), followed by December (12.01%).
With a rate of just 3.8%, July was the month in which the least enquiries were made. The data also found that demand for boiler repairs or replacements was lower between the months of March and October, with demand rising on either side of this period.
While this information does not discredit the idea that boiler inactivity can lead to breakdowns, it does suggest that issues stemming from high usage (wear and tear or burnout), or cold weather (frozen pipes), are among the most common reasons for boiler issues.
The most readable boiler manuals by company
Often, a concise and easily digestible manual can negate the need for callouts, by educating customers on the main boiler fault codes, error codes, and meanings of symbols on boilers. By having this basic knowledge at their disposal, consumers are able to manage their boilers in an appropriate fashion and take basic troubleshooting steps when necessary.
With this in mind, Uswitch conducted a study on the 10 most popular boiler brands in the UK, based on their number of Trustpilot reviews. Looking at a selection of instruction manuals for different types of boilers from each manufacturer, we gave each company an average score out of 100, to determine which brand had the most readable boiler manuals.
Average readability scores for manuals of boiler companies
| Boiler brand | Number of manuals analysed | Average readability score | Ranking |
|---|---|---|---|
| Ideal | 14 | 61.4 | 1 |
| Alpha | 15 | 60.59 | 2 |
| Intergas | 6 | 60.07 | 3 |
| Vaillant | 5 | 59.71 | 4 |
| Baxi | 18 | 59.63 | 5 |
| Worcester | 18 | 58.82 | 6 |
| Glowworm | 22 | 58.35 | 7 |
| Viessmann | 6 | 56.06 | 8 |
| Vokera | 17 | 54.93 | 9 |
| Atag | 9 | 53.35 | 10 |
(Source: Uswitch via Trustpilot and Python)
UK boiler statistics from our study indicate a significant readability difference of over 8% between the manuals of the highest-scoring and lowest-scoring companies. With an impressive average score of 61.4 across 14 manuals, Ideal was found to be the company with the most readable boiler manuals.
Ideal was run close by two other companies, with both Alpha and Intergas achieving scores above 60.
The bottom place was occupied by Atag. With an average score of 53.35, this indicates the Dutch company has considerable room for improvement when it comes to the readability of its instruction manuals.
Atag was joined at the foot of our table by Vokera and Viessman, who finished eighth and ninth, with scores of 54.93 and 56.06, respectively.
The future of home heating
Around 17% of UK emissions come from households. Therefore, the decarbonisation of our homes will play an important part in meeting the 2030 emissions target set out by the Fifth Carbon Budget.
The carbon footprint of an average UK home has been reduced by 4.7 tonnes of CO2 since 1990. A further reduction of 3.6 tonnes is needed by 2030, to help keep us on track.
There are a number of ways in which UK households could be modified, to help us reach the 2030 target for emissions, such as:
One in 20 UK homes with a gas boiler could join a heat network. This would save two tonnes of CO2 per year.
One in four homes currently using oil heating, and one in three homes using electric heating, could switch to a heat pump. This would reduce CO2 emissions by 3.2 tonnes and 0.8 tonnes per year, respectively.
Low-carbon electricity generation could reduce emissions by 79%, thus saving 1.25 tonnes of CO2 per year for the average UK home.
The Department for Business, Energy and Industrial Strategy (BEIS) released a Heat and Buildings Strategy in 2021, outlining a comprehensive plan for cutting emissions from UK buildings. This will cost £6.6 billion while saving people money on their bills and simultaneously reducing the country’s carbon footprint.
Part of this strategy involved a nationwide ban on installing and using gas boilers from all new-build properties by 2025 and for all households by 2035. From these dates, new heating systems must be fuelled either by heat pumps, hydrogen-ready boilers, or similarly low-carbon alternatives. However, in a September 2023 announcement, Prime Minister Rishi Sunak announced that the aim was to reduce the installation of gas boilers in new builds by 80%, rather than ban them completely.
In recent years, the boiler industry has become a replacement market. In the coming years, people will begin to substitute gas boilers for heat pumps, in an attempt to reduce their carbon footprint further and increase the efficiency of their domestic boiler systems.
According to the latest UK boiler stats, the UK Government has set a target of around 600,000 new heat pumps to be installed in UK households by 2028 as part of their Heat and Buildings Strategy 2021. There are associated installation challenges faced by this, with costs of up to £10,000, compared to £2,500 for the average gas combi boiler. However, these estimates don’t take into account the additional costs of extra insulation (such as draft-proofing disused vents) for homes in EPC Band E or below.
The planned introduction of a Future Homes Standard in 2025 will require new homes to have 75% less CO2 than at present. Part of this will involve preventing the installation of natural gas boiler systems in new-build properties. By 2035, the proposal is also to phase out the sale of natural gas and oil boilers in at least 80% of homes.
Alternatives to gas central heating
With 23 million homes in the UK having a gas boiler, sooner or later, they will need replacing. The UK government is aiming for a low-carbon production capacity of 5GW by 2030, with hydrogen being cited as a possible alternative to traditional gas boilers.
However, a decision is yet to be reached as to whether hydrogen boilers can be installed in homes from 2026.
FAQs about boilers
How long do boilers last?
The average lifespan of a boiler is typically between 10-15 years. In some instances, your boiler may last considerably shorter or longer than this period, based on the type of boiler, the volume of use, and how well the boiler has been maintained. Ensuring your boiler is regularly serviced and well-maintained will increase the chances of it lasting longer.
How big is the boiler industry?
According to IBIS World, the value of the UK boilers and radiators industry in 2022 is £1.6bn. The industry is ranked as the 78th largest manufacturing industry in the UK and the 290th largest overall.
How many boilers are there in the UK?
According to the Climate Change Committee, approximately 23 million UK homes are connected to the gas grid through a boiler and wet-based central heating system. 600,000 boilers per year will need to be replaced from 2028 onwards if the UK is to meet its target of becoming net zero by 2050.
What percentage of UK homes have gas central heating?
A 2022 report from Boiler Guide found that 86% of UK homes were found to have gas central heating systems.
Is gas central heating being phased out?
The latest government legislation has outlined plans to ban gas and oil boilers from being installed in any newly built home after 2025. Instead, these homes will be heated by low-carbon, renewable heating systems. This plan does not extend to homes built before 2025, however, previously built homes could still install gas central heating systems after this time period.
In September 2023, it was announced that the plan to phase out gas boilers from new builds had been reduced from a 100% target to 80%.
What is the alternative to a gas boiler?
There are more low-carbon, environmentally friendly alternatives to gas central heating than ever before, including heat pumps, solar thermal panels, infrared panels, and biomass boilers.
Does a boiler affect EPC rating?
Yes, your heating system has a significant impact on your EPC rating. With older boilers typically less efficient to run, upgrading your boiler to a newer one can improve your EPC score and help reduce energy bills.
What is a good efficiency rating for a boiler?
A boiler's efficiency rating is a good indicator of how much it will cost you to run. Most modern boilers have an A-rating, meaning they have an efficiency of 90% or more and are likely to cost less to run. If your boiler's efficiency is below 85%, then it’s likely that it’s at least 15 years old, and will be more costly to run than a newer boiler.
Boiler terminology and glossary
Air Source Heat Pumps (ASHPs)
A renewable energy source that extracts energy from the air outside to heat your home and provide hot water.
Biomass boiler
A low-carbon boiler that burns wood pellets, chips, or logs to heat your home and provide water.
Boiler magnetic filter
A device that collects magnetic debris in a heating system caused by rust and corrosion. The purpose of a boiler magnetic filter is to prevent blockages and breakdowns caused by a buildup of debris that can form a sludge-like substance within the pipes.
Combination (Combi) boiler
A system that provides heating and hot water solutions in one unit.
Commercial boiler
A system that provides heating and hot water to a non-domestic building (e.g. shops and business premises).
Condensate pipe
A pipe that safely transfers acidic wastewater produced during a boiler's condensing process out of the property via an external drain.
Decarbonisation
The measures taken by a business, entity, government, or organisation to reduce their production of carbon emissions.
Direct FTE
Full-time, or full time equivalent (FTE), jobs relating to the manufacturing of a product. Direct FTE refers to employees who either work the standard full-time 40-hour week or work their company’s equivalent of full-time hours.
Domestic boiler
A system that provides heating and hot water to homes and other non-commercial premises.
Flow temperature
The temperature that a boiler heats up water before it circulates around the house via radiators.
Ground Source Heat Pumps (GSHPs)
A renewable energy source in which energy is extracted from the ground outside your home to heat your home and provide hot water.
Indirect FTE
An employee who works full-time hours (or equivalent) in a field not directly affecting the manufacturing of their company’s product (e.g. sales or distribution).
Hydrogen-ready boiler
A gas-fired heating boiler that is capable of burning either natural gas or pure hydrogen.
Liquified Petroleum Gas (LPG) boiler
LPG boilers work similarly to standard gas boilers but are powered by liquified petroleum gas from a storage tank rather than the gas mains.
Thermostatic Radiator Valves (TRVs)
A valve that self-regulates, allowing you to adjust the flow of water into your boiler depending on the setting. This is also commonly seen on radiators.
Water cylinder
A water storage tank used to contain hot water in certain boilers and central heating systems.
Wood pellet boiler
A type of biomass boiler that is powered by wood pellets being inserted into the hopper (this can be done manually or automatically). The pellets are then burned to generate heat.
Sources and methodology
https://www.researchandmarkets.com/reports/5566801/uk-boiler-insurance-market-2023-2028-by-type
https://www.constructionleadershipcouncil.co.uk/news/construction-product-availability-statement-11/
https://www.constructionleadershipcouncil.co.uk/news/construction-product-availability-statement-17/
https://www.statista.com/statistics/426988/united-kingdom-uk-heating-methods/
https://www.statista.com/statistics/289137/central-heating-in-households-in-the-uk/
https://www.checkatrade.com/blog/cost-guides/new-boiler-cost/
https://www.checkatrade.com/blog/cost-guides/cost-smart-thermostat/
https://www.checkatrade.com/blog/cost-guides/boiler-repair-costs/
https://www.ons.gov.uk/economy/inflationandpriceindices/timeseries/kj5u/mm23
https://www.boilerjuice.com/heating-oil-prices/
https://www.reportlinker.com/p06317613/Commercial-Boiler-Global-Market-Report.html?utm_source=GNW
https://energyhouse2.salford.ac.uk/energy-house-labs/energy-house/
https://media.nesta.org.uk/documents/Boiler_Campaign_-_Evidence_Summary_.pdf
https://www.nea.org.uk/who-we-are/about-nea/
https://media.nesta.org.uk/documents/UoS_Nesta_Energy_House_Initial_Report_-_FINAL_2022-10-08.pdf
https://www.ofgem.gov.uk/energy-price-cap
https://energysavingtrust.org.uk/advice/boilers/
https://energysavingtrust.org.uk/about-us/our-data/
https://www.gov.uk/government/statistics/boiler-upgrade-scheme-statistics-september-2022
https://www.boilerguide.co.uk/articles/uk-boiler-breakdown-study
https://www.resolutionfoundation.org/major-programme/housing-outlook/housing-outlook/
https://www.theccc.org.uk/wp-content/uploads/2016/07/5CB-Infographic-FINAL-.pdf
https://www.bbc.co.uk/news/business-60235709
https://www.phamnews.co.uk/2022-predictions-what-lies-ahead-for-the-industry/
https://www.hvnplus.co.uk/news/hv-low-carbon-summit-time-for-a-clear-end-date-for-natural-gas-boiler-sales-19-10-2022/ https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1051408/2020-final-greenhouse-gas-emissions-statistical-release.pdf
https://www.theguardian.com/politics/2023/sep/20/uk-net-zero-policies-scrapped-what-do-changes-mean
https://www.ibisworld.com/united-kingdom/market-size/radiator-boiler-manufacturing/
https://www.boilerguide.co.uk/articles/central-heating-systems
Boiler efficiency comparison across the UK
https://epc.opendatacommunities.org/domestic/search
https://statistics.gov.scot/data/domestic-energy-performance-certificates
Best boiler brands in the UK 2022
https://uk.trustpilot.com/categories/boiler_manufacturer?sort=reviews_count
https://www.nltk.org/index.html
https://github.com/cjhutto/vaderSentiment
Average readability scores for manuals of boiler companies
https://uk.trustpilot.com/categories/boiler_manufacturer
https://www.freeboilermanuals.com/
https://pypi.org/project/PyPDF2/
https://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_tests#Flesch_reading_ease
https://pypi.org/project/textstat
