2025 Combi Boiler Installation:
Typical Investment Across the UK in 2025, homeowners can expect to spend between £1,800 and £6,000 for a fully installed combi boiler.
On average, most 3-bedroom properties will land at about £2,755 all-in.
• Supply cost for the boiler itself (from basic to top-tier models): £600 – £3,000
• Labour and fitting (including power flush, minor pipework alterations): £1,000 – £2,500
What Drives the Final Price Every installation is unique.
Here’s what typically nudges your quote up or down:
• Brand and model tier (budget range vs premium manufacturers)
• Boiler output rating (kW capacity matched to home size and bathrooms)
• Energy efficiency sticker (higher ErP ratings come with a premium)
• Warranty period (standard 5-year cover vs extended 10-year plans)
• Complexity of work (removing old cylinders, rerouting flues, adding valves)
• Regional labour rates and Gas Safe engineer availability
Modern Combi boilers also tend to be the most energy efficient as they deliver a fast supply of instant
hot water whenever a tap is turned on.
As Combi boilers have the ability to provide on-demand heating and hot water without needing any
additional components, they are particularly ideal for flats and houses where space is restricted.
When it comes to choosing a combi boiler for your home, we always recommend you compare models and costs from some of the top rated and most reliable brands. Prices differ according to the manufacturer and the overall boiler quality, but there are plenty of combi boilers available to suit all budgets.
Combi Boiler Sizes and Prices Dependent on the size of your house, combi boilers prices will differ.
Selecting the right size (KW output) Combi Boiler for your home is extremely important.
If you choose a boiler that’s too small for your property, it won’t be able to produce the right amount of heating and hot water to meet your needs.
However, this does not necessarily mean that you should purchase a big boiler.
When you install a combi boiler that is too big for your home, you’ll waste energy and spend more money on your fuel bills.
We have put together a guide that shows you some of the most suitable combi boiler options for the size of your home to make it easy for you to compare models, warranties and costs.
Our guide is designed to give you a rough idea of the appropriate boiler output,
so you’ll still need to ask a qualified heating engineer to help you work out the correct size combi boiler for you and your property.
Additional Cost Insights for Your 2025 Combi Boiler
Price by Fuel Type Gas Combi Boilers: Most common choice. Expect £1,750–£4,000 installed.
LPG Combi Boilers: Ideal for off-gas areas. Add £300–£600 to gas boiler prices due to tank supply.
Electric Combi Boilers: Pure electric units run £2,500–£5,500 installed—no flue work but higher running costs.
Annual Running Costs Estimate based on a medium-sized home using central heating (12,000 kWh/year):
Gas Boiler: ~£600–£800/year LPG Boiler: ~£1,000–£1,200/year
Electric Boiler: ~£1,400–£1,700/year State average energy tariffs when quoting these figures, and remind readers they’ll vary by supplier and usage.
Servicing & Maintenance Annual Service: £80–£120 for a basic Gas Safe check.
Powerflush (every 5–7 years): £300–£500 to clear sludge buildup.
Parts Replacement: Magnetic filter: £50–£150 (plus labour)
Thermostat upgrade: £80–£200
Highlight that regular servicing maintains efficiency and protects warranties.
Optional Extras & Upgrades Smart Controls: £150–£300 to add Wi-Fi thermostats or zoning for multi-room control.
Extended Warranty: 5 years included on most models; 10 years costs an extra £150–£300 upfront.
Flue Extension: £50–£150 if the termination point needs relocating.
Grants, Subsidies & Finance ECO4 Scheme: Income-based grants of up to 100% cover installation for eligible households.
Boiler Upgrade Scheme (BUS): Offers vouchers up to £5,000 for low-carbon heating (heat pumps, hydrogen-ready boilers).
0% APR Finance: Many installers partner with lenders to spread costs over 12–48 months.
Regional Price Variations Labour and call-out fees differ across the UK:
London & Southeast: +10–20% above national average
Midlands & North: on or slightly below average
Rural/Islands: +15–25% due to travel and specialist engineer rates
Encourage visitors to obtain multiple local quotes.
Return on Investment (ROI) Upgrading from a G-rated combi to an A-rated model can save £150–£300/year.
At current prices, payback period is typically 7–10 years (before factoring in grants).
When you start shopping around for a new combi boiler, you’ll soon discover that there is a huge variety of brands and models on the market today.
As a new boiler is a costly investment, it makes sense to consider combi boiler options from well-known manufacturers with an excellent reputation for producing quality boilers that are built to last. Below, you can find a table that includes just some of the best combi boilers on offer from the UK’s most popular brands.
Reputable consumer magazine, Which?
conducts tests and surveys to help members of the public pick the best appliances (including boilers) for their homes.
The magazine gives each boiler brand an overall score based on a combination of things, such as build quality, owner satisfaction, product reliability and heating engineer recommendation.
Which? is also known for awarding ‘Best Buy’ status to boilers and other products that are not just great but the best your money can buy.
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