Combi boilers cost between £520 and £4,000 for an average 3-bedroom home.
A-rated boilers will cost £620 to £1,260 to run annually, depending on your energy consumption.
The labour costs of a combi boiler installation are usually £1,000 to £2,000, however, swapping boiler types can cost £2,000 to £3,000.
Combi boilers are the most common heating solution in the UK. They provide the best efficiency for gas-powered heating systems and supply on-demand heating and hot water. In the UK, the cost of a new combi boiler is between £600 and £4,000 before installation, with an average price of £3,800.
If you're wondering, "How much is a combi boiler going to cost for my home?", the answer can be a bit tricky. Every home is different and requires a thorough inspection from a professional to get accurate labour costs. That's why a reliable professional is crucial. However, finding one can be challenging, requiring hours of research and calling up companies.
Instead, why not let us take the wheel? Fill out a short form, and receive up to 3 free, non-binding quotes from installers in your area. Click the button below to get started.
So, how much is a new combi boiler going to cost compared to other boilers? In the table below, we've outlined combi boiler prices and the average price of combi boilers in each fuel category.
Cost of a combi boiler in the UK
Boiler type
Cost excl. installation
Cost inc. installation (£1,000 – £2,000)
Average inc. installation
Gas
£520 – £5,300
£1,600 – £5,300
£3,800
Oil
£1,300 – £4,600
£1,600 – £6,500
£4,200
Electric
£650 – £3,000
£1,500 – £5,000
£3,250
Aside from the fuel, the size of your home is another consideration for what combi boiler one should buy. The easiest way to do this is by matching the size/output of the combi boiler to the size of your home.
Combi boiler prices per house size
Household size
Combi boiler size
Combi boiler unit cost
Average cost (incl. installation £1,500)
Small
1 - 2 bedroom
18kW - 27kW
£600 - £1,700
£2,650
Medium
3 - 4 bedroom
28kW - 34kW
£700 - £2,900
£3,300
Large
4+ bedrooms
35kW - 43kW
£800 - £4,000
£3,900
*These prices are estimates. For an accurate assessment of costs, contact a heating installer.
Most brands produce combi boilers for a 3 bed house with one bathroom as a benchmark. Combis are generally not the best boilers for homes with over 5 bedrooms, however, high-power models can accommodate these larger properties. Most heating engineers recommend system and conventional boilers for homes that have multiple bathrooms and 4+ bedrooms.
Combi boiler costs can vary based on numerous factors:
Type of combi: The output size, efficiency, and fuel type can all impact the cost.
Manufacturer and model: Different manufacturers charge varying prices. Foreign manufacturers may even incur import costs, while regional manufacturers in the UK can be less pricier. However, a good manufacturer will provide better accessibility to parts and a better warranty.
Type of installation: The cost of a combi boiler replacement will be cheaper than that of system and conventional boilers since like-for-like boiler replacements require less work.
Installer rates: Installers can charge more based on the amount of work needed, which region you're in, and their own personal rates. These typically range from £300 – £500/day.
Combi boiler prices per brand
The price table below lists how much combi boilers are for popular brands. Often, a new boiler cost will be above £900 for a good boiler such as the Viessmann Vitodens range. Similarly, you don't have to pay an exorbitant purchase price for the best combi boilers, but they can get more expensive for high-power models.
Combi boiler prices per manufacturer
Brand/ Model
Output
Efficiency
Price
Worcester Bosch Greenstar 4000
25kW – 30kW
94%
£1,100 – £1,400
Viessmann Vitodens 050-W
25kW – 35kW
92%
£900 – £1,300
Ideal Logic Max²
24kW – 35kW
94%
£1,200 – £1,400
EHC Mercury Electric Combi
12kW – 26kW
99% – 100%
£1,400 – £1,850
While there are some cheap boilers worth investing in, they can come with drawbacks. It's best to research them well in terms of output, efficiency, warranty, and the reliability of the manufacturer.
Combi boiler running costs in the UK
Combi boilers are designed primarily for small to medium-sized homes and can be a great appliance for cutting down on running costs. Combi boiler efficiency rates are usually above 90%, which makes them A-rated. The table below shows the costs of running them:
How much does a combi boiler cost to run?
Fuel type
Combi boiler running cost (monthly)
Gas
£51.67 to £105
Oil
£100 to £129
Electric*
£194 to £500
*Assumes 12 hours of heating at £0.27 per kWh for electricity as per April 1st, 2025 price cap
Installation costs of a combi boiler
So, how much is a new combi boiler in terms of labour and installation costs? Generally, boiler replacement will cost between £1,000 and £2,500 for most homes. The exact price can depend on a few factors, such as what boiler was there before and whether the home's pipework needs to be overhauled to make space for a new boiler.
Cost of combi boiler installation
Installation type
Days
Installation cost
Combi to combi
1 to 2 days
£1,200 – £3,500
Conventional to combi
2 days
£2,500 – £4,500
System to combi
2 days
£1,200 – £3,500
Back boiler to combi
2 to 3 days
£2,000 – £4,000
Switching out a conventional or system boiler in larger homes should be done after diligent research. If you're swapping them out, finding a combi boiler for a 4 bed house or larger home requires matching output and water flow since standard combis are meant for lower water consumption. The output should be above 28kW, while the water flow needs to be higher than 16LPM (litres per minute).
It's best to contact an installer to find out how much it will cost to install a combi boiler. They can give you the best breakdown after assessing your property. However, finding one on your own can be a hassle involving researching, calling up companies, and comparing prices.
Our service can simplify the process down to filling out a 30-second form, after which you'll receive up to 3 different quotes from reliable, local installers.
Click the button below to gain access to multiple companies we've personally vetted.
During servicing, an engineer will check to see what can be improved, try out the functions, and see if everything is operational. It's recommended that you get your boiler checked out every 12 months by an OFTEC-qualified engineer.
Cost of combi boiler servicing
Type of boiler
Cost
Gas
£70 – £130
Oil
£80 – £300
Electric
£60 – £120
Better boilers will require less maintenance and have better warranties, which is why it's important to get a boiler from a recognised manufacturer. Additionally, a proper installation can spare a lot of the headaches related to performance.
Financing a combi boiler
There are numerous financing options for combi boilers, including:
ECO4 grant: Homeowners in England, Wales, and Scotland can apply for the ECO4 scheme until in March 2026 to receive funding for a better condensing boiler. Households with gross annual income of £31,000 or less are eligible if they habe an EPC (Energy Performance Certificate) rating of D and below. They need to be connected to the gas mains supply with an existing boiler older tha 8+ years. The grant amount per household can be up to £20,000, but this is based on an assessment of your home, which may recommend measures other than a boiler.
0% loans: These have a higher rate of return but will have no interest.
Regular loans: These are usually on 11% to 15% APR (Annual Percentage Rate).
How much is a new combi boiler loan payment? That depends on:
The price of the boiler: Bigger loans will need a bigger payout, but not every loan has to cover the entire price of the boiler.
The length of the loan: Longer loan payments can have lower monthly payments, but will have higher interest accumulation over time.
How much interest is attached to it: Different companies provide different interest rates. Rates can also alter based on how long you want the loan to be, with longer payments accruing more interest payouts over time.
The credit history of the applicant: Applicants with a better credit history will receive more favourable loan conditions.
Find fitted combi boiler prices near your UK home
If you're wondering, "How much does a combi boiler cost in my area?", our service can help you out. Finding installers is a laborious task that takes way too long if done on your own.
That's why we've narrowed it down to filling out a 30-second form, after which we handle the rest. You'll receive the best prices from reputable installers we've personally vetted.
Click the button below to receive up to 3 free, non-binding quotes from installers in your area.
Combi boilers cost between £1,600 to £6,000, with an average price of about £3,800 after installation. The prices of combi boilers can vary based on many factors.
How much does an engineer charge to fit a combi boiler?
You can get combi boilers for free with the ECO4 scheme in England, Scotland, and Wales, if you meet the criteria. There are also other financing options available.
About the author
Rawal Ahmed
Rawal Ahmed is a writer at Boiler Guide with an interest in sustainability and a background in background in tech journalism and digital marketing.
Compare boilers
Try our boiler comparison tool
Find the best boiler for your needs, or see how the latest A-rated boilers compare with each
other and your existing one.
