Find out how much it costs to fit a boiler in 2025. Compare prices by type, region, and property size, and discover the factors that influence your total installation cost.

According to the Energy Savings Trust, heating and hot water account for over 50% of your energy costs, so fitting an efficient condensing boiler can make a huge difference. For many homeowners, the question isn’t whether to upgrade but how much the installation will actually cost.

Replacing a boiler is one of the most significant home energy investments you’ll ever make, and the price can swing wildly depending on your property, the system you choose, and the complexity of the job. Installation quotes can range anywhere from a few thousand pounds for a straightforward swap to well over £4,000 when extra pipework, flue extensions, or system conversions are involved.

It’s a confusing landscape, especially when every installer seems to use slightly different language or pricing methods. Understanding what you’re really paying for can save you hundreds of pounds and ensure your home runs efficiently for years to come.

Whether you’re replacing an old combi boiler or converting from a traditional system, knowing the current 2025 figures helps you budget with confidence and avoid unexpected costs.

Key Takeaways on How Much to Fit A Boiler in the UK:

• The average cost to install a new boiler in the UK in 2025 is £1,800–£4,800, depending on the type and complexity of the job.
• The Energy Saving Trust reports that a typical A-rated gas boiler with thermostatic radiator valves costs around £3,700, including installation.
• A like-for-like combi replacement is usually the most affordable option, averaging £2,000–£3,000.
• Conversions or relocations can raise costs to £3,500–£4,500 because of added labour and materials.
• Always use a Gas Safe-registered installer and request an itemised quote showing labour, parts, VAT, and warranty details.
• Smart controls and thermostatic radiator valves can improve comfort and help reduce energy use after installation.

Average Cost to Fit a Boiler in the UK (2025)

The average cost to install a new boiler in the UK ranges between £1,600 and £4,800, depending on the type of boiler, the size of your home, and the complexity of the installation. According to the Energy Saving Trust, a new A-rated gas boiler with thermostatic radiator valves typically costs around £3,700.

The largest share of costs often comes from labour rather than the boiler itself, particularly if new pipework, a flue extension, or heating controls are required.

For most households, a straightforward combi-to-combi replacement is easier and cheaper than conversions or system upgrades. The table below provides an at-a-glance view of the most common setups and the typical homeowner costs in 2025.

Boiler Type	Supply Only (£)	Installation (£)	Total Fitted Cost (£)	Best For	Quick-Buy Tip
Combi	700–1,500	900–2,000	1,600–3,500	Flats & small-to-medium homes	Compact and efficient – perfect for one-bathroom properties
System	900–1,900	1,200–2,400	2,100–4,300	Medium-to-large family homes	Handles multiple bathrooms with consistent pressure
Regular (Conventional)	800–1,600	1,200–2,000	2,000–3,600	Older homes with existing tanks	Best when upgrading without major pipework changes

Prices can vary across the UK. For the most accurate estimate, installers will factor in your current system, boiler location, and any upgrades to controls or pipework.

What’s Included in the Cost to Fit A Boiler?

When you see a quote for a “boiler fitting,” it can sound simple, but the installation cost actually covers a range of skilled work. A professional installer doesn’t just attach a few pipes. They ensure your entire heating system operates safely, efficiently, and in compliance with UK Building Regulations.

A standard installation quote typically includes:

• Removal of the old boiler – Safely disconnecting, draining, and disposing of your existing system.
• Installing the new boiler – Mounting the unit, connecting pipework, fitting the flue, and checking all seals.
• System flushing – Cleaning out sludge and debris to protect the new boiler and improve efficiency.
• Magnetic filter fitting – Often added to stop rust and dirt from entering the system.
• Wiring and thermostat connection – Linking smart or standard controls for easy temperature management.
• Safety testing and commissioning – Checking gas pressure, emissions, and system performance before certification.

How Long Does it Take to Fit A Boiler?

A like-for-like combi swap typically takes around one working day, while system conversions or relocations can take two to three days. Most installers conclude with a comprehensive safety test and a brief demonstration of how to operate your new boiler.

Quick Checklist For Comparing Quotes

Before you accept an installation price, make sure you know what’s included:

• Is the removal of your old boiler covered?
• Does the quote include a system flush or filter?
• Are thermostat controls part of the package?
• Is VAT included in the total?
• Will the installer register your warranty and provide certification?

Knowing exactly what you’re paying for helps avoid surprise costs later and ensures you’re getting a professional, Gas Safe-standard installation.

How Much to Fit A Boiler By Type and Scenario

The final price of a boiler installation depends on what kind of system you already have and whether you’re simply replacing it or making a full upgrade. While the Energy Saving Trust lists the average cost of a new A-rated boiler with valves at around £3,700, the real figure for your home could be several hundred pounds lower or higher, depending on the scenario.

Like-For-Like Combi Replacement

A direct combi-to-combi swap is the quickest and most affordable job. Most UK homeowners pay between £1,900 and £2,800, depending on the brand and installer. The work usually takes one day, with minimal pipework changes. This is ideal for modern flats and smaller homes with a single bathroom.

Converting From A System or Regular Boiler To A Combi

If you’re replacing an older boiler that uses a hot-water cylinder, expect a higher total. Converting to a combi typically costs between £2,900 and £4,500. This reflects the extra labour needed to remove tanks, reroute pipework, and upgrade controls. The job can take two to three days, but it often frees up space and improves heating efficiency.

Moving The Boiler To A New Location

Relocating a boiler, for instance, from the kitchen to a utility room or loft, adds £400 to £900 to the total. This covers the extra pipework, a new flue opening, and extended wiring. Properties with thicker walls or long flue runs can expect to be at the top of that range.

Adding Thermostatic Radiator Valves

Thermostatic radiator valves (TRVs) cost about £40–£60 each. These small controls allow you to set different temperatures in each room, helping the boiler work more efficiently and potentially reducing gas use by up to 10%.

Upgrading To Smart Heating Controls

Many homeowners now add smart thermostats such as Hive, Nest, or Tado during installation. This typically costs £180–£300, but helps lower annual heating bills by £100 or more through better scheduling and remote control.

How Region and Property Size Affect Costs to Fit A Boiler

Boiler installation costs vary noticeably across the UK. Labour rates, property size, and access all play a role. Prices in London or the South East can be 10–25% higher than in the Midlands or the North.

Large homes also need more powerful boilers and, in some cases, additional system components such as hot-water cylinders or expansion vessels. The table below shows how prices shift by region and property type.

Property Type	Typical Region	Boiler Type	Estimated Total Cost (£)	Notes
1-bed flat	North West	Combi	1,800–2,400	Compact unit, minimal pipework
2-bed terrace	Midlands	Combi	2,200–2,900	Straightforward like-for-like swap
3-bed semi-detached	South West	System	2,800–3,800	May include new controls or TRVs
4-bed detached	London & South East	System or Regular	3,800–4,800	Higher labour costs and longer installation time
5-bed rural home	Scotland / Wales	Regular	3,500–4,600	May require a flue upgrade or a larger boiler

Why Location Matters

Installers in densely populated or high-cost areas charge more for labour, parking, and compliance paperwork. In rural regions, costs can rise due to travel time and limited availability of Gas Safe engineers.

Why Property Size Matters

Larger homes generally need boilers with higher heat outputs and more radiators to balance, which means more pipework and longer installation time. Small flats, on the other hand, often benefit from compact combi boilers that are quicker and cheaper to fit.

For the most accurate estimate, request at least three quotes from local installers. Each will assess not just the boiler, but the full heating layout, including flue route, water pressure, and control compatibility, before confirming a final price.

What Factors Impact Costs to Fit A Boiler?

You must consider the following factors when calculating how much to fit a boiler in the UK:

Type of Boiler You Want To Install

The installation process varies depending on the type of boiler you pick.

Combi boilers are often the least expensive to install, whereas traditional boilers are the most expensive.

In addition, the boiler’s power source, which might be gas or electricity, also affects how much it costs.

A gas combi boiler is often less expensive than a traditional gas boiler.

Wondering how much a new boiler costs? Check out our guide on options available if you need a new boiler but can’t afford it, as well as boilers on finance and government boiler grants here.

Size of The Boiler (Dimensions)

The size of the boiler is another important factor that influences the price you are given for boiler installation.

Larger boilers are more expensive to install than smaller boilers, as a matter of convention.

Large boilers may require two to three people to lift and install, influencing the labour costs of installation.

Check out our video on how to vet boiler brands/models in the UK:

Where You Fit the Boiler in the UK

The cost of installing a boiler is determined by the labour required.

This varies depending on your location, the company you hire, the time it takes to install the boiler, and the number of engineers needed.

Depending on the installation style, a new boiler will, on average, cost between £600 and £1,500.

For example, a combi swap is much quicker and can take around a day to complete, while a back boiler conversion can take around two days and require more than one engineer.

The Need For Additional Upgrades

Any renovations or adjustments you may require when the new boiler is installed are additional factors that impact the costs you are charged for boiler installation.

In some circumstances, additional pipes, valves, or electrical outlets may be required to accommodate the new boiler being installed.

You should anticipate paying more if you need renovations or alterations to the pipes or power source than someone who does not.

Boiler Conversion or Relocation

Some boiler upgrades are simple, and some are not.

A standard boiler install entails loosening a few connections, removing the old boiler, and installing the new boiler.

In this case, your boiler installer can test the boiler immediately and sign it off as gas-safe. However, not all boiler installs are that straightforward.

If your new boiler type does not match your old one, the contractor may need to drill the holes again wherever needed and even modify the plumbing to install it.

Moving the location of your boiler is also costly and will require a lot of physical labour, new fixtures and fittings, and additional pipework.

All this requires time, increasing the expense of installing your new boiler.

Want to learn about all the factors that contribute to a boiler quote? Check out our boiler cost calculator to understand the latest deals and what is factored into a gas boiler replacement estimate.

Vertical Flue Cost

A vertical flue can cost from £300 to £600.

The boiler flue is a pipe that leads from the boiler to the outside of your home. It helps ensure condensation and the boiler’s emissions are pumped out of your home.

If the flue leaves your property horizontally, you’ll incur no costs. However, if it leaves the property vertically through the roof, it will require more work, resulting in additional costs.

Gas Pipe Upgrade

If you have an old heating system, you’ll need to upgrade the gas piping to meet modern regulations.

Gas pipes with a width of 15mm must be upgraded to at least 22mm, attracting additional costs of around £250 to £400.

Sometimes, older pipes must be replaced entirely, especially if made of lead. Some installation companies don’t charge for upgrading pipework, so ensure you shop around.

Plume Kit Cost

If your boiler flue is too close to a door, window, or neighbouring property, a plume kit is necessary to comply with Gas Safe regulations.

The plume kit helps extend the flue and ensure a safe exit for harmful gases, costing from £90 to £130.

Upgraded Heating Controls

Almost all new boiler installations will include some upgraded controllers.

A wide range of heating controls is available to help your heating system work more efficiently and keep your bills down.

Depending on the type and brand of the controller, it will add varying amounts to the cost of your new boiler, ranging from £100 to £300.

Chemical Flush

A chemical flush will help clear any existing sludge or debris from your heating system, costing from £100 to £150.

Sludge can prevent hot water from flowing to your radiators effectively, making it difficult to heat your home comfortably.

A chemical flush is common and standard, but you can also get a power flush for up to £500. However, you should be cautious to avoid damaging an old heating system by forcing high-pressure water through it.

Radiator Costs

When fitting a new boiler, ensure you look at your overall heating system, including radiators.

Radiators experience wear and tear after years of use. Old radiator models can also be less efficient and perform poorly compared to modern models.

The efficiency of the radiators will directly impact the overall efficiency of the boiler and heating system.

Incorporating features like thermostatic radiator valves (TRVs) can enhance control over individual room temperatures, contributing to energy-efficient heating and cost savings.

The price of new radiators can vary depending on factors like size, design, material, and the number you require.

How to Get Accurate Quotes for Costs to Fit A Boiler

Boiler installation prices can vary widely, even within the same postcode. The best way to avoid overpaying or missing important details is to collect at least three written quotes from qualified installers and compare them carefully. Every quote should clearly explain what’s included, who will carry out the work, and how long it will take.

Step 1: Check Gas Safe Registration

Only Gas Safe-registered engineers are legally allowed to install or service gas boilers in the UK. You can verify a business or installer at the Gas Safe Register website. Never rely on verbal confirmation alone; always ask to see their registration card.

Step 2: Request An Itemised Quote

Ask for a breakdown that separates the boiler price, labour, and any extras such as filters, smart controls, or a system flush. A professional installer should list VAT and warranty details upfront. If the quote seems too brief or vague, request clarification before agreeing.

Step 3: Compare Like-For-Like

Make sure you’re comparing the same type of work across all quotes. For example, one installer might include a magnetic filter or flue extension, while another charges separately. Aligning the details ensures you’re making a fair comparison.

Step 4: Ask About Warranties and Aftercare

Check what warranty is included with the boiler and who will register it. Many leading brands require the installer to complete the registration within 30 days of fitting. It’s also worth confirming whether a free first-year service or follow-up visit is included.

Step 5: Confirm Timescales and Certification

Standard installations take one to three days, depending on complexity. Make sure your quote includes both the expected timescale and confirmation that the engineer will issue a Building Regulations Compliance Certificate once the work is completed.

Keep all quotes and paperwork for your records. These documents are essential for warranty claims, home insurance, and future resale.

Can You Get A Grant To Cover the Costs to Fit A Boiler?

Various government grants are available in the UK, Wales, and Scotland to help with the cost of fitting a new boiler. These include:

The Energy Company Obligation (ECO4) Scheme

 ECO4 requires energy suppliers to fit energy-saving measures to help households reduce home heating costs and decarbonise.

If you qualify for a boiler grant, ECO4 can help cover the cost of replacing, repairing, or upgrading your boiler.

The scheme targets fuel-poor, low-income, and vulnerable households and will run until March 2026. Eligibility is based on criteria such as home ownership, benefits, income, and proof of need.

Boiler Upgrade Scheme (BUS)

The BUS scheme provides grants to encourage property owners to replace existing fossil fuel heating systems with low-carbon, more efficient heating systems.

These include ground-source heat pumps, air-source heat pumps, and biomass boilers in limited circumstances.

If you can’t afford boiler costs and qualify under BUS, you can get up to £5,000 to cover the upfront costs of installing a biomass boiler.

The scheme opened for grant applications on 23^rd May 2022 and will run up to 2025 with a £450m funding confirmed for the three years.

If you don’t qualify for the boiler grants, you can get a boiler on finance, known as a pay-monthly boiler or rent-a-boiler.

With boilers on finance, you can install a new boiler in your home without paying the full price before installation.

Instead, you can spread the cost of your new boiler with an affordable monthly pay deal, with no upfront payment and no hidden charges.

Are you considering paying for your boiler monthly? Many boiler finance deals make paying for a new boiler much more manageable.

Final Thoughts on How Much To Fit A Boiler

Fitting a new boiler is one of the most significant home upgrades a homeowner can make, both in cost and comfort. A typical A-rated gas boiler with thermostatic radiator valves costs around £3,700 on average, including installation. Real-world prices can fall below or rise above that figure depending on boiler type, property size, and how complex the job is.

Across the UK, straightforward replacements usually cost between £2,000 and £3,000, while conversions or relocations sit in the £3,500 to £4,500 range. What matters most is ensuring the work is done safely and efficiently by a Gas Safe-registered installer, and that every quote clearly sets out what’s included.

Choosing an efficient condensing boiler, fitted correctly and paired with modern heating controls, not only improves reliability but also helps reduce overall energy use. With careful comparison and clear expectations, homeowners can make a confident, informed decision that delivers warmth, safety, and long-term value.

FAQs on How Much to Fit A New Boiler

What Is The Cost Of Fitting A New Boiler?

In 2025, the average cost to supply and fit a new boiler in the UK ranges between £1,800 and £4,800, depending on the type of boiler and the complexity of the installation. The Energy Saving Trust places the typical figure for an A-rated gas boiler with thermostatic radiator valves at around £3,700.

How Much Is A Boiler Service In 2025?

A standard annual gas boiler service costs between £80 and £120 in 2025, based on average prices. This includes safety checks, cleaning, and performance testing carried out by a Gas Safe-registered engineer.

How Much Is A New Boiler For A Three-Bedroom House?

A typical three-bedroom home in the UK usually needs a 24–30 kW combi or system boiler. The full installation cost generally falls between £2,500 and £3,800, depending on the brand and whether any pipework or controls need upgrading.

How Long Does It Take To Fit A New Boiler?

A like-for-like boiler replacement usually takes one working day. Conversions, such as changing from a regular or system boiler to a combi, can take two to three days, especially if new pipework or a flue relocation is required.

What Size Boiler Do I Need For A 4 Bedroom House?

Most four-bedroom homes require a boiler with an output of 30–40 kW, depending on the number of bathrooms and radiators. System boilers are often recommended for larger properties with higher hot-water demand.

Sources and References

• Energy Saving Trust – Boiler types explained
• GOV.UK – Boiler Upgrade Scheme