Condensing Boiler Costs in the UK

Last updated: November 15, 2023

What is the average cost of a new condensing boiler in the UK? Here we summarise the average costs and the factors boiler installation companies take into consideration.

Important reminder: if you have an old G rated boiler, upgrading to a modern A rated condensing boiler could potentially save you up to £300 per year on heating costs.

In this guide we explore condensing boiler standalone costs, as well as installation costs and common installation scenarios.

Of course, all homes and situations are unique, but these examples will give you an idea of how much you can expect to pay.

Condensing Boiler Costs Quick Summary

The quick and short answer is that the average condensing boiler install in the UK costs between £1,500 and £5,000, if you have the most common type of boiler i.e. a combi boiler and want a like for like swap, it will cost somewhere between £1,500 and £3,000.

The final price you will pay for the boiler and Gas Safe installation depends on a variety of factors that we will cover in more depth below, but to summarise:

  • The type of condensing boiler e.g. combi boiler, system or heat only.
  • The brand of the condensing boiler.
  • The boiler warranty length that comes with the condensing boiler.
  • If you want the boiler moving to a new location in your property.
  • The location of the boiler e.g. in some cases scaffolding may be required, which can increase the price.
  • Any extras e.g. radiator’s, pipework, a power flush or thermostats.
  • Whether it’s an emergency call-out or not.
  • Associated labour costs in your area.
Best boilers

Types of Condensing Boilers in the UK

As mentioned, the type of boiler you have installed can impact the final cost.

In the UK, there are three main types of gas condensing boilers installed into households, they include the following:

Combi or Combination Boilers

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

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

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

Important note: since 2005, all new domestic boilers sold in the UK are condensing boilers and use “condensing” technology.  

Did you know the efficiency of your boiler can impact the amount of energy it uses and ultimately impact your heating bill costs? Check out our guide to the best condensing boilers if you are interested to find out more. 

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

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New Boiler Cost Guides by Boiler Type: 

System Boilers

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

System boilers have their own internal pump and are fed with water from the mains, which is then stored in a separate hot water cylinder/tank.

This means they can handle a high hot water demand e.g. more than one bathroom being used at once and without any drop in waterflow or pressure.

Heat-Only Boilers

Heat-only boilers or regular  boilers are an older version of the system boiler and work in a very 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.

As mentioned the cost of a boiler quote can be impacted by the type of boiler and typically combi boilers are easier to install since they have fewer components.

Boiler Brand

Like any other type of home appliance some brands are more expensive than others. Sometimes this is justified and some times it isn’t.

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

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

Boiler Warranty Period

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

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 much be much lower e.g. 2 years vs 10 year boiler warranties.

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

Got a common boiler problem? Check out our quick fix guide on boiler lockoutboiler ignition faultsboiler PCB faultsfaulty diverter valves and boiler timer issues.

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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 Boilers Location

It’s typically cheaper to have your boiler installed in the same place it was, so if you do want to move your boiler to a new place e.g. upstairs or in the attic, you should expect to pay more.

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: 

Will you need Scaffolding?

In some cases, scaffolding will be required to replace your boiler, this is usually if it’s at a very high position and 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, so this 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.

Do you require any extras?

If you want extras then this needs to be factored into the quote. For example, it’s going to be cheaper to just have your boiler replaced with the same type of boiler in the same location compared to you having a different type of boiler installed in a different location.

It’s also going to cost more if you want extras e.g. a new boiler and all your radiators replaced at the same time.

Did you know that not only boiler models are wall-hung either, check out our complete guide on floor standing boilers here.

Emergency Install vs Pre-Planned Install

If you boiler breaks down suddenly in the depths of winter and you need it replacing 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 replacing urgently.

Boiler upgrades

Common Condensing Boiler Installation Scenarios (and Costs)

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

Straightforward Combi Combi Swap

If you already have a gas combi boiler and you want it replacing with a new combi boiler and in the same location, the good news is that this is considered relatively straightforward and one of the easiest types of boiler installations.

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How much does a straightforward combi swap cost?

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.

A Boiler Conversion

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

As previously discussed the major reason for this is all the additional components that need to be installed and/or removed e.g. the water tank, header tank etc. This means it can take more time and labour and cost more in materials.

What size boiler is right for your home? If you are thinking about a combi boiler, it is largely determined by the number of radiators in your home.

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.

How much does a boiler conversion cost?

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

Back Boiler Replacement

If you have an old fashioned back boiler like the Baxi Bermuda (typically found above the fireplace) this will need to be decommissioned and removed and then a new boiler e.g. a combi boiler installed in a suitable location.

Similar to a boiler conversion, replacing a back boiler takes more time and labour and more materials are usually required.

Additionally, if the back boiler is in a high-up location, scaffolding may be required which can also add to the costs.

How much does a back boiler replacement cost?

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

Condensing Boiler Installation Costs Summary

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

If you want to secure the best price for your new boiler, it’s always advised to seek multiple quotes from a range of different suppliers.

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.

As previously highlighted, some 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 that wasn’t considered at the time the quote was provided.

Also, always remember to check the installers previous customer reviews, which is easy to do on platforms like Trustpilot and ensure that they are on the Gas register and are legally allowed to install a gas boiler.