How much does it cost to replace a boiler?

The average cost of replacing a boiler is £1,500 - £2,700

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Average cost
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How much does it cost to replace a boiler? graph showing high and low prices for boiler repair

Things to consider

  • Is your tradesperson Gas Safe registered?
  • Do you want a combi, system or conventional boiler?
  • Which type of boiler would best suit your home?
  • What capacity or power of boiler do you need?
  • Do you have the space for a storage tank?
  • Do you want your boiler fitted in the same location or somewhere new?
  • Which brands offer the best warranty?

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What you’re paying for


Boilers always seem to find the worst possible time to let you down. Like before a cold snap hits. Or ahead of an influx of guests who’ll overuse your shower. Boilers need to be serviced every year to make sure they’re safe and running efficiently, but it’s all too easy to forget and find yourself dealing with a boiler breakdown.

Replacing an old boiler requires specific skills and experience, as well as – for gas systems – accreditations like Gas Safe registration to make sure they’re fitted safely. The range of boiler options can be confusing and that’s why it’s wise to call upon the knowledge of an experienced heating engineer. They’ll be able to recommend the right system for your home and advise on the best brands on the market.

A breakdown of boiler replacement costs is provided below, and we’ve listed some things to bear in mind when choosing your boiler. We’ve also included some guidance to help you understand the differences between each system and their benefits.

Bear in mind that extra work may need to be carried out to allow for your new boiler, such as pipework or internal wall adjustments. If the work’s needed, it could mean additional costs on top of the immediate bill for your boiler.


How much does boiler installation cost?


The average cost of boiler supply and installation is £1,750.

The cost of the boiler installation largely depends on the type of system you go for and where it will be installed.

A heating engineer will work out which option is best suited to your home, taking into consideration the size of your property, value for money and efficiency. They’ll be able to talk through the different boiler brands that are available and the relative strengths of each model.

If you’re on a tight budget, then replacing your existing boiler in the same location and with the same type of system will be the most cost-effective solution. You’ll pay more if you want to swap your boiler to a new location, as that’ll require your heating engineer to move pipes.

Once you’ve decided where your boiler will live, your engineer can supply and fit the boiler. This usually takes at least the best part of a day – maybe more. They may also be able to dispose of the old system, so ask about that before work begins.  


How much does it cost to install a combi boiler?


The average cost of a combi boiler supply and installation is £1,850.

Flats and smaller homes often choose a combi boiler heating system. These boilers aren’t just energy efficient – they’re extremely compact and convenient too, providing hot water on demand. That means there’s no waiting around for a water cylinder to heat up. They’re also the cheapest type of boiler on the market.

Whether this is the right option for you depends on the size of your property and how many people live there. If you live on your own, or with just one other person, then this is a good option. As combi boilers take up limited space, there’s no need for a tank in your loft or a hot water cylinder.

Combi boilers can also deliver hot water at a decent water pressure (depending on the model you choose). It’s worth checking what mains water pressure you have before going ahead with the installation though. The drawback of combi boilers – and this is a consideration for families or those with a number of people living in a home – is that lower-powered models are only able to provide a decent flow of water to one bath, shower or tap at a time. That can be inconvenient.

Back to the positives – there’s limited pipework needed to run a combi boiler, and installation times are therefore much quicker. This means you won’t have to fork out for extra labour costs and materials. As with all boilers, combi models will need to be serviced regularly (usually annually) to ensure a long life and smooth operation.


How much does it cost to install a system boiler?


The average cost of a system boiler supply and installation is £1,650.

Larger households typically opt for a system boiler – using mains water for cold and a storage cylinder for hot water – as they’re capable of serving up a generous supply whenever you need it. System boilers provide a consistent flow of water to any number of taps, baths and showers throughout the house.

Just like combi boilers, system boilers don’t require a loft tank, meaning you’ll have more space (and it won’t prevent you from having a loft conversion in the future). This also minimises the risk of frozen or leaking pipes which could cause your home to flood. One thing to keep in mind is that if you’re replacing a combi boiler with a system boiler, then you’ll need to find space for a hot water cylinder somewhere.

Installation times are generally pretty quick thanks to the built-in components. This means system boilers tend to look quite neat too.


How much does it cost to install a conventional boiler?


The average cost of a conventional boiler supply and installation is £1,800.

Conventional boilers are the most traditional heating systems and they’ve been around for decades. They’re gradually being phased out and replaced by more modern systems but they’ll still be suited to homes with cold water storage tanks in the loft.

The installation process is fairly straightforward and shouldn’t take your heating engineer too long to complete. It just depends on whether new gas pipes need to be fitted and the system re-sealed, which could add to the price.

Unlike combi and system boilers, a conventional boiler setup requires a cold-water storage tank, as well as another tank to ensure the water level of the central heating system is maintained. Both tanks are usually positioned above the boiler and cylinder, and work by supplying the cylinder using gravity to flow water in. You’ll need to find additional space for the cylinder – your airing cupboard will usually be your best bet.

If your property has an older heating system, you may be better off sticking with a conventional boiler. Modern alternatives deliver water at high speed, which an older system would struggle to cope with. Although conventional boilers are less efficient than the latest options, they’re compatible with solar water heating systems, which could bring your energy costs down and reduce your carbon footprint.


Appendix – Costs

Low Average High
General boiler installation costs
Combi (28kW)– no boiler currently installed £1,500 £2,200 £3,000
Combi (28kW)– combi boiler currently installed – including flue kit £1,500 £1,850 £2,300
Combi – conventional boiler currently installed £1,500 £2,000 £2,500
Combi – system boiler currently installed £2,000 £2,500 £3,000
Conventional – no boiler currently installed £2,500 £3,000 £3,500
Conventional – combi currently installed £2,200 £2,700 £3,200
Conventional – conventional boiler currently installed £1,500 £1,800 £2,300
Conventional – system boiler currently installed £1,500 £1,800 £2,300
System (28kW) – no boiler currently installed £1,850 £2,500 £3,000
System – combi boiler currently installed £2,200 £2,700 £3,200
System – conventional boiler currently installed £1,500 £1,800 £2,300
System (28kW)– system boiler currently installed – including flue kit £1,500 £1,650 £2,300
Complete system costs
3-bed house (including piping and boiler) £3,000 £3,500 £4,000
4-bed house (including piping and boiler) £4,000 £4,500 £5,000
5-bed house (including piping and boiler) £5,000 £5,500 £6,000


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