Cost guides › New boiler
United Kingdom
How much does a new boiler cost?
Replacing a gas combi boiler like-for-like, in the same position, typically costs £2,800 including VAT, and most quotes fall between £2,200 and £3,650. A budget boiler with a shorter warranty comes in around £2,250, while a premium boiler with a 10 to 12 year warranty and smart controls is closer to £3,750. Moving the boiler, a new flue route or converting from a tank-fed system are what push a quote well above that.
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mid-range, typicalCost by region
| Location | Basic | Mid-range | Premium |
|---|---|---|---|
| London | £2,350 | £2,900 | £3,850 |
| Scotland | £2,250 | £2,850 | £3,750 |
| East | £2,200 | £2,800 | £3,700 |
| North West | £2,200 | £2,800 | £3,700 |
| South East | £2,250 | £2,800 | £3,750 |
| South West | £2,200 | £2,800 | £3,700 |
| West Midlands | £2,200 | £2,800 | £3,700 |
| East Midlands | £2,200 | £2,750 | £3,700 |
| North East | £2,200 | £2,750 | £3,700 |
| Wales | £2,200 | £2,750 | £3,700 |
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| Yorkshire and The Humber | £2,200 | £2,750 | £3,650 |
What's included
Mid-range
- Disconnecting, removing and disposing of the old boiler
- A new 24 kW condensing combi boiler from a mid-range brand
- Gas, heating, water and condensate connections to the new boiler
- A standard flue kit through the existing flue position
- Chemical system clean, inhibitor and a magnetic system filter
- A programmable load-compensating room thermostat, which meets Boiler Plus for a combi in England
- Gas tightness test, commissioning, the Benchmark checklist and building regulations notification by the Gas Safe engineer
What affects the cost
Boiler type
A combi swapped for a combi is the cheapest job. System and regular boilers cost about the same to replace if the cylinder and tanks stay, but converting a tank-fed system to a combi means taking out the cylinder and loft tanks and re-piping the hot and cold water, which usually adds an extra day of work.
Brand and warranty
Budget models with 5 to 7 year warranties cost noticeably less than premium boilers from the big manufacturers with 10 to 12 year cover. Check that the longer warranty is registered and what servicing it requires; many are void without an annual service.
Flue route and boiler position
Our figure assumes the new boiler goes where the old one was, with a standard horizontal flue. A vertical flue through the roof, a longer flue with extensions, or scaffolding for access all add cost. Moving the boiler to another room needs new gas, water and condensate runs and is one of the biggest extras on a quote.
Condition of the heating system
Manufacturers expect the system to be cleaned before a new boiler goes on, so a chemical clean and a magnetic filter are included here. A heavily sludged system with cold spots on radiators may need a full power flush, which is priced separately.
Gas supply pipe
A modern combi often needs a larger gas pipe than the old boiler had, especially on a long run from the meter. If the engineer finds the pipe is undersized, upgrading it is extra and not included here.
Controls
In England a combi installation must include one extra efficiency measure, and a load-compensating thermostat is the simplest way to meet it. A smart thermostat with app control costs a little more but also counts.
How to save
- Keep the boiler in the same place if you can; a relocation often costs more than upgrading the boiler itself.
- Get at least three written quotes from Gas Safe registered engineers and compare the same boiler model, warranty length and extras line by line.
- Only pay for a power flush if the engineer shows you evidence of sludge, such as cold spots or dirty system water; a chemical clean and filter are often enough.
- Replace before the old boiler fails completely, so you can wait for a quote you are happy with instead of paying emergency rates in winter.
Grants, tax and rules
Gas Safe registration is the law
Only a Gas Safe registered engineer may install, move or disconnect a gas boiler; it is illegal for anyone else to do it. Check the engineer's ID card and that their registration covers boilers. They also notify building control, and you should receive a Building Regulations compliance certificate.
Boiler Plus in England
Since April 2018, new gas boilers in England must reach at least 92% ErP efficiency and come with a timer and room thermostat. A new combi also needs one of: weather compensation, load compensation, smart controls with automation and optimisation, or flue gas heat recovery.
Hydrogen-ready boilers
There is no requirement to buy a hydrogen-ready boiler. The government plans a decision in 2026 on whether hydrogen will be used for home heating, and has said that only if it gets a substantive role would new boilers have to be hydrogen-ready, and then only from 2030. Any gas boiler you buy today runs on natural gas.
VAT and grants
A new gas boiler is charged at the standard 20% VAT, which our figures include. The Boiler Upgrade Scheme's £7,500 applies to heat pumps, not gas boilers, if you are weighing up the switch.
Frequently asked questions
How much does a new combi boiler cost fitted?
A like-for-like combi swap in the same position costs around £2,800 including VAT, with most quotes between £2,200 and £3,650. The price rises if the flue needs changing, the boiler moves or the gas pipe must be upgraded.
How much does it cost to convert to a combi boiler?
Converting a regular or system boiler to a combi costs noticeably more than a straight swap, because the cylinder and loft tanks come out and the hot and cold pipework is changed, usually over two to three days. Choose that option in the calculator to see the price for your area.
Do I need a power flush with a new boiler?
Not always. Manufacturers require the system to be cleaned, which a chemical clean and magnetic filter usually satisfy. A full power flush is worth it where radiators have cold spots or the system water is black with sludge.
How long does it take to replace a boiler?
A like-for-like combi swap is usually done in a day. Conversions and relocations take two to three days, as there is more pipework to change.
Should I buy a hydrogen-ready boiler?
It is not required and should not cost you extra. The government has not yet decided on hydrogen for home heating, and hydrogen-ready boilers run on natural gas like any other.
Is it worth replacing a working boiler?
If it is over 15 years old, non-condensing, or needs expensive repairs, a new condensing boiler usually uses less gas and comes with a new warranty. If it is working well and under 10 years old, a service is usually the better spend.
How this estimate is calculated
Work hours: 16.5 · Labour: £792 · Materials: £1,550
Sources: ONS Annual Survey of Hours and Earnings, tables 14 and 15; Regione Toscana, Prezzario dei Lavori 2026 (CC BY 4.0); ECB exchange rates; market check: Mid = like-for-like combi, mid-range brand, chemical flush, filter, compliant controls. Checkatrade new-boiler-cost (2026): like-for-like combi 2,500-4,000, gas boiler avg 3,000; Heatable (dateModified 2026-09-25): median combi swap 2,300 from 2,000 quotes Jan-Jun 2026, most 2,150-3,000; bestbuilders.co.uk (May 2026): combi swap 1,800-2,800, premium 3,000-4,200. Incl. 20% VAT..
Last reviewed 26 September 2026 · How we calculate costs · Editorial policy