How much does a new boiler cost?

Boiler installation costs vary enormously, depending on how much work is required, the parts needed, their availability and even where you live.

Here's how much you should expect to pay for a new boiler installation. Plus, you'll find advice on how you can make payments through finance schemes.

Always make sure your engineer is a trusted expert – you'll depend on them to get your boiler working efficiently and you'll want to make sure you're happy with what you're paying for. 

Note that all Which? Trusted Traders have been thoroughly vetted by us.

Our experts will help you buy a boiler that won't let you down – discover the best boiler brands.

The average cost of a new boiler

The price you pay for a new boiler will vary depending on:

• Boiler type – If you're getting a heat-only boiler, system boiler or combi boiler, there might be extra costs if you need to fit a hot water cylinder.
• Boiler brand/model – Although most boiler brands offer models at different price points, some brands are cheaper overall. Getting a reliable boiler is the most important thing to consider when deciding which brand to go for as it will save you money and stress in the long run.
• Boiler size – The larger the boiler (in kilowatts) the more expensive it usually is.

The prices below should give you a good indication. Thanks to South Essex Plumbing and Heating for supplying prices for us.

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Not sure which type you should get for your home? Consult our guide: What are the different types of boiler?

How much does it cost to install a boiler?

The cost of installation will include the price of the new boiler, a system clean and labour, plus any additional extras you want.

Overall costs will also be affected by the amount of work the engineer needs to do to fit the boiler. For example, if they need to change pipework or alter the location, then you should expect labour costs to be higher.

Where you are in the UK will also affect the prices you pay. Engineers in London and the South East will probably cost more than those in other regions, for example. Data also shows that customers living rurally might pay more than customers in some urban areas because there's less labour supply and competition.

Lots of engineers will quote you a total sum for the work needed instead of an itemised bill. That's because installation jobs can't always be broken down meaningfully into itemised steps, and you can't opt in or out of different parts of the process.  Even if the engineer only quotes one sum, they should still be able to explain the costs to you in a more detailed breakdown, even if this is a verbal conversation you have. 

From the outset, these are some factors that may add or take away from your installation costs:

• A like-for-like swap, such as swapping one 24kW combi boiler for another, will be easier and cheaper.
• If you need a larger boiler, for example if you've extended your home or converted it to add another bathroom, you might need a bigger supply line to the gas meter (between £100 and £400).
• If you need to relocate your boiler, this will increase costs and you'll need new piping.
• If you're swapping a combi for a boiler with a hot water tank, you'll pay £350-£750 for a vented cylinder or £900-£1,400 for an unvented cylinder, depending on the size of the cylinder.
• If you're swapping from an old heat-only or system boiler to a new combi (a common swap), expect an extra £400-£800 for the extra labour and re-piping. 
• If you're installing extra heating controls for your boiler, it'll cost around £100-£250 for a smart thermostat, and £35 to £80 per smart radiator valve. A normal thermostatic radiator valve is about £15. 
• If your heating system is cleaned (important so that your new boiler can run efficiently), you can expect a power flush, used to clean heavily sludged systems. This ranges in cost from £300-£750 for a five-radiator system, with an average cost of £500.

Oil boiler installations

Installation of the following oil systems should be carried out by a trained professional:

• An oil-fired combustion appliance, which has a rated heat output of 100kW or less, and which is installed in a building with no more than three storeys (excluding any basement) or in a dwelling;
• Oil storage tanks and the pipes connecting them to combustion appliances;
• Heating and/or hot water service systems connected to an oil-fired combustion appliance.

If you can't find a local Trusted Trader, there are several schemes, listed below, to help you track down a suitable person for oil appliances. You can find more details on these websites:

• Association of Plumbing and Heating Contractors (APHC)
• The Building Engineering Services Competence Assessment Ltd (BESCA)
• NAPIT 
• OFTEC 

Like gas boilers, you can expect lower installation costs if you're directly swapping your current oil boiler for a similar model. If you're swapping the type of boiler, relocating where your oil boiler is or needs a lot of old fittings replacing, then the costs will increase.

Additionally, you may have to install an oil store (including piping from the store to the boiler). Smaller oil stores, suitably for smaller boilers and houses that have easier access to oil supplies typically cost around £1,300. If your home has a larger oil boiler, or is in a remote location where you'll want a larger store to ensure you need to rely on fewer deliveries, this will cost around £2,400.

Boiler financing - how to pay for a boiler and installation 

Unfortunately, most often when people buy a new boiler it's an emergency situation and an unavoidable expense. 

However there are a few options when it comes to paying for a new boiler and installation.

If possible, we recommend keeping some savings ring fenced to make sure you could pay off a boiler and installation within four years at the most, as a term longer than that can involve expensive interest charges.

Pay up front

If you have the money, you should pay the full figure up front. Make sure you get a few quotes from local installers, check reviews and opt for the one you trust the most. Use our figures as a guide, but bear in mind that there will be regional differences, the costs will depend on the design of your system and what's needed, and the impacts of high inflation will see some costs going up.

0% APR finance

If you need to borrow to afford your boiler, it's a better deal if you can avoid interest on the loan. The downside is that the term for paying the loan will be shorter than finance options with interest charges (two years is a common timeframe). 

• Which? Trusted Trader Heatable offers £0 deposit, 4 years 0% APR
• Which? Trusted Trader iHeat offers £0 deposit, 2 years 0% APR. 

Other companies offering similar packages include British Gas (£0 deposit, 4 years 0% APR) and Warmzilla (£0 deposit, 2 years 0% APR).

You may be able to pay a deposit with cash you already have and then pay smaller instalments over the term. For example, if you swap a combi boiler with another combi for £2,600 and you're able to pay £1,000 up-front, a 0% interest loan paid over three years will be approximately £44/month instead of £72/month. Whichever you go for, check that you're happy with the terms of the loan. 

Boiler finance

Engineers, companies and energy suppliers offer boiler finance over all sorts of terms, possibly even allowing you to pay the boiler off over a decade. 

But generally speaking, the longer you take to pay off the loan, the more interest you'll be paying. This is why, if at all possible, paying up-front or getting a 0% interest loan over a shorter period is better.

For example, British Gas offers a 2-3 year interest-free boiler loan at 0% APR, but its 10-year loan plan has an interest rate of 9.9% APR.

To avoid relying on this sort of financing, it's best to stress test your finances and try to pay off a boiler within four years instead. 

The government offers grants for consumers to ditch their gas and oil boilers to get heat pumps and biomass boilers instead. Read about boiler grants to find out more.

Finding a registered boiler installer

You should always get a gas boiler installed by a gas safe-registered engineer. The Gas Safe Register provides details of registered installers in your area. Alternatively, call Gas Safe on 0800 408 5500.

Each installer must carry an ID card, which lists the gas work they're qualified to do.

Which? Trusted Traders are vetted heating engineers who are all gas safe registered. You can use our Which? Trusted Traders search tool to find a reliable local tradesman near you. You don't have to be a Which? member to use Which? Trusted Traders.

Before you call an installer, make sure you've got a good grounding in what to expect when you get a new boiler. 

Check out our guide on how to buy the best boiler. If you're unsure what type you need, take a look at our guide to different types of boiler.