New Boiler Cost Explained: Boiler Price Plus Fitting

“How much is a new boiler?” is one of the most searched heating questions in the UK, and most answers online give a single figure that rarely matches the quote you end up with. That is because a new boiler cost is two separate things added together: the boiler itself, and the work to fit it in your home. The first can be looked up. The second depends on what the engineer finds when they see the job.

This guide explains both halves, what makes the fitting simpler or bigger, and how to compare quotes so you are not caught out.

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What Does the Boiler Itself Cost?

The boiler unit is the part with a public price. Merchants such as Screwfix, Toolstation and City Plumbing list them online. In early October 2026, boiler-only prices for popular combis, including VAT, ranged from roughly £980 for a smaller Baxi 600 Combi 2 to around £2,200 for a Worcester Bosch Greenstar 8000 Life 40C, with Vaillant ecoTEC plus bundles (boiler, flue and protection kit) reaching about £2,700.

Our guide to the best combi boilers for 2026 breaks this down model by model, with sources. Two things to remember:

• The listing may not include everything. Some prices are for the boiler alone. Others bundle a flue or a filter.
• The installer usually supplies the boiler. Many will not fit a boiler you have bought yourself, and the longest warranties often require an accredited installer to fit and register it.

Why Can’t Anyone Give a Fixed Price for the Fitting Without Seeing the Job?

Because no two installations are the same. A straight swap in a modern flat and a conversion in a Victorian terrace with a loft tank are completely different jobs, even with the same boiler. An honest engineer will look at the home, or at good photos, before quoting the fitting. A price given over the phone without any of that is either a guess or a starting figure that grows later.

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What Makes Boiler Fitting Simpler?

The fitting tends to be at its most straightforward when:

• It is a like-for-like swap. Combi to combi, or system to system, in the same place.
• The boiler stays where it is. Existing gas, water, heating and condensate connections can often be reused or adapted.
• The flue can follow the same route and still meets the current distance rules.
• The gas supply is already big enough for the new boiler’s output.
• The heating system is in reasonable condition and only needs a standard clean and treatment.

What Makes Boiler Fitting a Bigger Job?

The work grows when the engineer needs to do any of these:

• Change boiler type. Converting from a conventional system with loft tanks and a cylinder to a combi means removing the tanks and cylinder, capping old pipes and changing pipework.
• Move the boiler. A new position means new gas, water, heating and condensate runs, and a new flue.
• Fit a new flue route. Vertical flues through the roof, long flue runs or awkward positions add time and parts.
• Upsize the gas pipe. Larger combis need a good gas supply. If the existing pipe is too small, part of the run has to be replaced.
• Clean a dirty system. A heavily sludged system may need a power flush, not just a chemical clean, before a new boiler goes on.
• Upgrade the controls. In England, a new combi must come with Boiler Plus controls, and each heated room should have its own thermostatic control, usually a TRV on each radiator. Missing TRVs need adding.
• Fit a magnetic filter. Most manufacturers need one for their longer warranties.
• Reroute the condensate pipe. External condensate pipes that freeze in winter often need rerouting or upsizing.
• Make good afterwards. Boxing in, patching plaster or reworking a kitchen cupboard can be part of the job.

Every gas boiler replacement must also be notified under Building Regulations. A Gas Safe registered engineer does this through the Gas Safe Register, and you should receive a Building Regulations Compliance Certificate, along with a completed Benchmark commissioning checklist. That paperwork should always be part of the job, not an extra.

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How to Compare Boiler Quotes Fairly

Quotes only compare properly when they describe the same job. Use these steps:

1. Ask for the boiler as a separate line, with the exact model and output, so you can check it against merchant prices.
2. Check what is included in the fitting: flue, filter, controls, TRVs, system clean, condensate work, removal of the old boiler and any tanks.
3. Confirm the warranty length and its conditions, including whether the installer is accredited by the manufacturer and will register the boiler for you.
4. Check the engineer is on the Gas Safe Register and qualified for the work, and ask to see their Gas Safe ID card on the day.
5. Ask how Building Regulations notification is handled and when you will receive the compliance certificate.
6. Get the scope in writing, including what happens if something unexpected is found, such as a gas pipe that needs upsizing.
7. Compare like with like. A lower quote that leaves out the filter, controls or system clean is not cheaper. It is a different job.

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Is a New Boiler Worth It, or Should You Repair the Old One?

It depends on the age of the boiler, how often it breaks down and whether parts are still available. Our guide on how long boilers last, and whether to repair or replace has a simple checklist. If your boiler has just failed and you want to see what a repair would involve first, see our boiler repair cost guide.

Can Photos Speed Up a Boiler Quote?

Yes. Clear photos of the current boiler (including its data badge), the flue outside, the gas meter and pipe, the airing cupboard and any loft tanks help an engineer understand the job before visiting. They can often tell straight away whether it looks like a simple swap or a bigger change.

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Get a No-Obligation Quote

For a no-obligation quote, call 07360 268948 or send photos of your current boiler on WhatsApp, and we’ll put you in touch with a local Gas Safe registered engineer who will quote for your home. Find out more about boiler replacement in the TW area.