Boiler Installation Cost Calculator – New Boiler Installation Costs

Last updated: June 12, 2024

Are you considering replacing your boiler with a brand new one and want to know the exact costs for the boiler and installation? This boiler installation cost calculator guide will help you find out.

If you’re struggling with an old or inefficient boiler, installing a new, A-rated boiler can save you up to £475 on fuel costs, depending on your home’s size and thermal performance.

The costs of maintaining and repairing an old or worn-out boiler can soon outweigh the cost of installing a new one.

Investing in a new, modern boiler is worthwhile as it allows you to enjoy higher efficiencies and peace of mind knowing it will operate reliably.

So, how much can you expect to pay? How do you know you’re not getting ripped off and how can you save money?

In this guide, we’re going to help you understand the many different factors that are taken into account, along with average costs for common installation scenarios, as well as costs for those considered a little more complicated.

Wondering which boiler manufacturers performed best? Check out our best boiler brands guide for the full rundown and if you are trying to determine who the best boiler installation company is, check out our Warmzilla and Boxt reviews.

Boiler installed after determining price with the boiler installation cost calculator guide
Image by Worcester Bosch

Boiler Installation Cost Calculator Quick Takeaways:

  • The average cost of a new combi boiler installation ranges from £1,500 to £4,500.
  • Factors like the brand, warranty length, type of boiler, location, installation complexity, and any extras can impact the final price.
  • The costs will also vary depending on whether you’re converting to a different boiler type, replacing it, or moving it to a new location.
  • To get an accurate quote for a new boiler, you can start your application with Which? approved boiler installers here.

How Much is a New Boiler Installation?

The cost of installing a new boiler in the UK will depend on whether you’re converting it to a different type, replacing it, or moving it to a new location.

The average combi boiler install costs between £1,500 and £4,500 in the UK.

However, this is for a standard, uncomplicated like-for-like swap. Straightforward replacements are quick and easy, making them less costly as they take the installer less time.

Comprehensive system upgrades, such as changing from an old back boiler to a high-efficiency combi boiler, can require extensive changes and work.

You may also need to pay for extra parts, pipework cleaning, modifications, or an extended warranty.

The final price will also depend on:

  • The cost of replacing a boiler. This can be influenced by the boiler type, brand, and model you choose.
  • The fuel type and size of the boiler. Larger and more powerful boilers can be more expensive.
  • How complex or complicated your specific installation scenario is.
  • The boiler warranty period.
  • Associated labour costs in your area.
  • If you want to move the boiler to a new location.
  • If you’re converting from one type of boiler to another.
  • Any extras like radiators, magnetic filters, or smart controls.
Best boilers

Boiler Installation Cost Calculator – Main Factors Considered:

As mentioned above, there are many factors you need to consider when working out how much a new boiler installation will ultimately cost you.

Here, we discuss them in more depth:

Type of Boiler

The type of boiler you want installed will impact the final cost.

The main types of boilers installed in UK households include:

Combi or Combination Boilers

Installing a new combi boiler can cost from £1,500 to £4,500. The cost will depend on the boiler type, warranty length, installation complexity, and labour costs in your area.

Combination boilers are by far the most common type of boiler used in UK homes. They can provide hot water on demand and heating water from a single unit, typically wall-hung.

Combination boilers take cold water directly from the mains and do not need a storage tank. Instead, they heat the water up when required.

For this reason, they are also easier to install and ideal for homes with limited space.

See also  Quietest Combi Boilers - Which is the Quietest Boiler in the UK in 2024?

Did you know your boiler’s efficiency can impact the energy it uses and, ultimately, your heating bill costs? Check out our guide to the best condensing boilers to learn more. 

You may also find our review of the best eco-friendly boilers of interest.

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

New Boiler Cost Guides by Boiler Type: 

System Boilers

System boilers are also popular in UK homes and ideal for properties with high hot water demand or areas with poor water pressure.

Installing a system boiler can cost anywhere from £1,500 to £5,000.

How much you pay will depend on factors like the brand, required controls, warranty length, additional valves or pumps, and the general complexity of the job.

System boilers have their own internal pump. The water is fed from the mains and stored in a separate hot water cylinder/tank.

This means they can handle a high hot water demand, such as when more than one bathroom is used at once, without any drop in flow rate or pressure.

The costs above are for installing the boiler only and don’t include the costs for new or replacement cylinders.

Heat-Only/Regular/Conventional Boilers

Installing regular or conventional boilers costs from £1,500 to £3,500.

The final price will depend on the brand, boiler size, and installation complexity. 

Heat-only boilers, or regular boilers, are older versions of the system boiler and work in a similar way.

The major difference is that they do not use an internal pump and instead work together with a header tank, which transports water using the natural force of gravity.

Electric Boilers

Depending on its size, model, and type, installing an electric boiler can cost between £ 2,000 and £4,500.

Electric boilers can be regular, combi, or system boilers powered by electricity from the National Grid, like your other appliances, rather than gas or oil.

Electric boilers are an eco-friendly alternative suitable for homes without gas access.

They’re highly efficient, easy to install, and release fewer emissions. However, electricity is usually more expensive than gas or oil and is generated by burning fossil fuels.

Combining an electric boiler with renewable energy sources like solar panels or solar thermal can make it a worthwhile investment since you’ll use free electricity.

The table below shows how much you can expect to pay for different types of boilers in the UK:

Type of Boiler/Fuel SourceCost Excluding InstallationCost Including InstallationAverage Cost Including Installation
Combi Swap£600 – £2,000£1,500 – £4,500£3,000
System Boiler£500 – £2,500£1,700 – £5,000£3,300
Conventional Boiler£600 – £3,500£1,700 – £4,500£3,000
Electric Boiler£600 – £2,500£2,000 – £4,500£2,500
Biomass Boiler£7,000 – £15,000£10,000 – £18,000£15,000

Table data updated June 2024. 

Boiler Brand

Like any other type of home appliance, some brands are more expensive than others. Sometimes, this is justified, and sometimes, it isn’t, but you must consider the brand in a boiler installation cost calculator.

For example, some boiler brands contain higher-grade and higher-quality components, such as stainless steel heat exchangers and all metal parts, as opposed to those that use plastic.

In addition, some brands have better reviews, longer warranty periods, and a reputation for superior customer service, which can be especially important in a boiler breakdown emergency.

Warranty Period

Perhaps one of the most important considerations when buying any boiler is the warranty length offered.

Ideally, you want the boiler warranty to be as long as possible. Not only is this a sure sign of a better quality boiler, but it also means you’ll be covered for repairs or a replacement for extra peace of mind.

Boiler Guarantee Vs Warranty

Often, you will find you can buy a boiler cheaper, but the warranty period will be much lower, e.g., 2 years vs 10-year boiler warranties.

See also  Changing From Conventional Boiler To Combi

Longer warranties usually feature higher prices, so you must factor this into a boiler installation cost calculator.

In addition, some brands offer a warranty, while others offer a guarantee, and while these do sound similar, there is a slight technical difference.

Essentially a warranty is an agreement from the manufacturer that they will diagnose and repair the boiler, but not necessarily entirely for free.

While a boiler guarantee is a promise that they will diagnose and repair the boiler free of charge.

Do you have a common boiler problem? Check out our quick-fix guide on boiler lockoutboiler ignition faultsboiler PCB faultsfaulty diverter valves, and boiler timer issues.

Boiler ManufacturerPeriod (Years)Guarantee or Warranty? 
Viessmann5-10 yearsWarranty
Ideal 5-10 yearsWarranty
Worcester Bosch5-10 yearsGuarantee
Vaillant5-10 yearsWarranty
BAXI3-10 yearsWarranty

Moving Your Boiler Location

It’s typically cheaper to have your boiler installed in the same place it was. However, you should expect to pay more if you want to move your boiler to a new location, such as upstairs or in the attic.

The reason for this is pretty simple – moving the boiler means re-positioning the pipework, which takes more time and costs more in materials.

Related reading: 

Your Location 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.


In some cases, scaffolding will be required to replace your boiler, usually if it’s at a very high position, which would be considered unsafe to do with just a ladder.

This is an added cost since contractors and installers typically rent the scaffolding for the installation, which is an additional expense they factor into the job.

It’s worth noting that some companies, e.g. Boxt and Heatable, do not always charge extra for this, and it’s all part of their “fixed price” promise.

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 work and 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.

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.


When fitting a new boiler, look at your entire heating system, including radiators.

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

See also  Boiler PCB Faults - How To Diagnose and Repair Costs UK

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

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 size, design, material, and the number you require.


If you want extras, this needs to be factored into the cost of new boiler installation.

Any renovations or adjustments you may require when the new boiler is installed are the 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.

Emergency Install vs Pre-Planned Install

If your boiler breaks down suddenly in the depths of winter and you need it replaced as soon as possible, you may be dealing with an out-of-hours emergency install, which will have a premium.

Although it’s not always possible, it’s far better to plan a boiler install in advance rather than waiting until it’s already broken and you need it replaced urgently.

Boiler upgrades

Common Boiler Installation Scenarios

Here are some of the most common boiler installation scenarios and their average costs:

Straightforward Combi Combi Swap

The installation can be cheaper if you already have a gas combi boiler and want to replace it with a new combi boiler in the same location.

This is considered relatively straightforward and one of the easiest types of boiler installations.

On average,  a combi boiler installation like this will cost between £1,500 and £2,000, depending on the brand, warranty, and area you live in.

New boiler cost guides:

A Boiler Conversion

If you want a boiler conversion, e.g., changing from a combi boiler to a system boiler or vice versa, this will typically cost more than a standard like-for-like replacement.

The average cost of a boiler conversion, e.g., swapping from a combi to a system, will cost between £1,800 and £2,500.

As previously discussed, the major reason for this is all the additional components the installer must add or remove, e.g., the water tank, header tank, etc.

This means it can take more time and labour and cost more in materials.

Check out our complete guide to new boiler installation here if you are wondering about the best type of boiler for your home. 

How much may a new boiler cost? Are you considering converting from a conventional to a combi boiler? Use our boiler installation cost calculator to get an estimation.

Back Boiler Replacement

The average cost of a back boiler replacement in the UK is between £2,000 and £2,500.

If you have an old-fashioned back boiler like the Baxi Bermuda (typically found above the fireplace), you’ll need to decommission and remove it. You’ll then install a new boiler, e.g., a combi boiler, in a suitable location.

Similar to a boiler conversion, replacing a back boiler takes more time and labour, and will require more materials.

Additionally, if the back boiler is in a high-up location, scaffolding will be required, which can increase the costs.

Did you know that not all boiler models are wall-hung? Check out our complete guide on floor-standing boilers here.

Boiler Installation Cost Calculator Summary

As you can appreciate from the many factors discussed above, the cost of a new boiler installation can vary greatly depending on your unique situation.

Seek multiple quotes from a range of different suppliers if you want to secure the best price for your new boiler.

This allows you to get a good picture of how difficult your particular job actually is and how much it costs from the perspective of multiple experts.

Many online boiler platforms now offer a “fixed price,” which essentially means they won’t charge for any extras should they turn up on the day of the job and discover something else they didn’t consider when they gave you the quote.

Also, always remember to check the installer’s previous customer reviews. You can do this easily on platforms like Trustpilot. You should also ensure that the installer is on the Gas Safe Register and is qualified to install a gas boiler.

Sources and References