Quick answer: a like-for-like combi boiler swap in the UK typically costs £1,800–£3,500 fitted, and converting a regular or system boiler to a combi £3,000–£5,700 (Heatable, checked September 2026). A yearly gas boiler service is typically £85–£120 (MyJobQuote). Grants mostly fund heat pumps rather than gas boilers.
Boiler cost checker
Pick a job to see the typical UK price range from published cost guides, with the source for each figure. It is a guide, not a quote.
Prices change and depend on the size of the job, the property, access and location. Figures were last checked . Always get a written quote before work starts.
Request a free quoteBoiler prices vary more than most home jobs because two quotes for “a new boiler” can describe very different work. A straight swap in the same cupboard is a day’s job; moving the boiler, changing the flue or taking out a hot water cylinder and tanks can take two or three days. The tables below use published UK cost guides, each checked in September 2026. Where we could not find a source for a figure, we have left it out rather than guess.
Boiler prices by job
These are typical installed ranges, including the boiler and labour. They are national figures; expect the upper end in London and the South East.
| Job | Typical range | Basis | Source |
|---|---|---|---|
| Like-for-like combi boiler swap | £1,800–£3,500 | Installed | Heatable cost guide, checked September 2026 |
| Premium combi boiler swap | £3,000–£4,500 | Installed | Heatable cost guide, checked September 2026 |
| System boiler replacement | £1,800–£3,500 | Installed | Heatable cost guide, checked September 2026 |
| Conventional (regular) boiler replacement | £1,800–£3,000 | Installed | Heatable cost guide, checked September 2026 |
| Regular or system boiler to combi conversion | £3,000–£5,700 | Installed | Heatable cost guide, checked September 2026 |
| Back boiler to combi conversion | £3,500–£6,000 | Installed | Heatable cost guide, checked September 2026 |
| Oil boiler replacement | £4,500–£5,500 | Installed | Heatable cost guide, checked September 2026 |
| Electric boiler installation | £1,700–£4,500 | Installed | Heatable cost guide, checked September 2026 |
| Gas boiler service | £85–£120 | Per service | MyJobQuote boiler service guide, checked September 2026 |
| Power flush | £400–£870 | Per system (6 to 20 radiators) | MyJobQuote power flush guide, checked September 2026 |
Heatable says its median quote for a standard combi replacement, across 2,000 quotes generated between January and June 2026, was £2,300. It is a boiler installer, so treat its figures as one company’s view of the market; they sit close to the other guides we read.
Combi boiler prices by size
MyJobQuote breaks combi costs down by the boiler’s output and the type of job. These are installed prices, including the boiler:
| Job | 24–27kW | 28–34kW | 35–42kW |
|---|---|---|---|
| Combi to combi, same place | £1,050–£2,250 | £1,200–£2,850 | £1,400–£3,700 |
| Combi to combi, new place | £1,300–£2,450 | £1,400–£3,150 | £1,550–£4,000 |
| System or regular to combi | £1,650–£3,050 | £1,750–£3,700 | £1,950–£4,750 |
For labour alone, MyJobQuote gives £550–£800 for a like-for-like combi swap (4 to 6 hours), £850–£1,150 to move the boiler (1 to 2 days) and £1,200–£1,700 to change boiler type (2 to 3 days). Source: Combi Boiler Installation Cost Guide (UK Prices 2026) (myjobquote.co.uk), checked September 2026.
Servicing, cleaning and extras
| Item | Typical cost | Source |
|---|---|---|
| Gas boiler service | £85–£120 | MyJobQuote boiler service guide |
| Oil boiler service | £90–£125 | MyJobQuote boiler service guide |
| LPG boiler service | £90–£120 | MyJobQuote boiler service guide |
| Power flush, 1 to 2 bed (6 to 8 radiators) | £400–£470 | MyJobQuote power flush guide |
| Power flush, 3 bed (8 to 10 radiators) | £470–£520 | MyJobQuote power flush guide |
| Power flush, 4 bed (10 to 12 radiators) | £520–£550 | MyJobQuote power flush guide |
| Magnetic filter, supplied and fitted | £180–£260 | MyJobQuote power flush guide |
| Boiler cover plan | £8–£13 a month, or £180–£300 a year | MyJobQuote boiler service guide |
MyJobQuote also notes labour rates are typically £10–£20 higher in London and the surrounding area than the UK average. For what a service should include, see what happens during a boiler service.
What pushes the price up
- Changing boiler type. Removing a hot water cylinder and loft tanks to fit a combi adds a day or more of labour and new pipework.
- Moving the boiler or flue. A new location means new gas, water and condensate runs, and the flue has to meet terminal position rules; see where a boiler flue can terminate.
- Back boilers. These sit behind a fireplace and usually need moving to a wall-mounted position, which is why Heatable puts the conversion at £3,500–£6,000.
- Fuel. Oil boiler replacements cost more than gas, and oil work needs an OFTEC-registered technician rather than a Gas Safe engineer.
- Warranty length and brand. Heatable’s premium combi range (£3,000–£4,500) reflects longer warranties and higher-spec models.
For a fuller breakdown, see new boiler installation costs: what changes the total price.
Grants and what they actually fund
| Scheme | Where | Gas boiler? | What it offers | Source |
|---|---|---|---|---|
| Boiler Upgrade Scheme | England and Wales | No | £7,500 towards an air or ground source heat pump, £5,000 towards a biomass boiler; an extra £1,500 until March 2027 for some off-gas homes heated by oil or LPG; no grant for hybrid systems | gov.uk |
| ECO4 | Great Britain | Can include heating replacement | Energy-supplier scheme for eligible low-income households; runs until 31 December 2026 | ofgem.gov.uk |
| Warm Homes: Local Grant | England, via councils | No (Greater Manchester says gas and oil boilers are not eligible) | Insulation and low carbon heating for low-income households in EPC D–G homes | greatermanchester-ca.gov.uk |
| Home Energy Scotland Grant and Loan | Scotland | No | Up to £7,500 grant plus optional £7,500 interest-free loan for a heat pump | homeenergyscotland.org |
Our local guides show how these work in London, Birmingham, Manchester, Glasgow and Leeds.
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Ask at least two Gas Safe registered engineers to quote for the same boiler model, output, flue, controls and warranty, so you are comparing like for like. Our checklist: how to compare boiler installation quotes.
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How much is a new combi boiler in the UK?
Typically £1,800–£3,500 fitted for a like-for-like swap (Heatable), or from about £1,050 for a smaller 24–27kW combi in the same place according to MyJobQuote. Premium models cost more.
Why is converting to a combi so much more expensive?
The engineer has to remove the cylinder and tanks, change pipework and often move the boiler. Heatable puts it at £3,000–£5,700, and MyJobQuote gives £1,200–£1,700 for the labour alone.
How much should a boiler service cost?
MyJobQuote gives £85–£120 for a gas boiler, £90–£125 for oil and £90–£120 for LPG.
Can I get a grant for a new gas boiler?
Rarely. The Boiler Upgrade Scheme, Warm Homes: Local Grant and Home Energy Scotland fund heat pumps and insulation rather than gas boilers. ECO4 can fund heating replacements for eligible households until 31 December 2026.
Is a power flush always needed with a new boiler?
Not always. It is usually quoted for older systems with sludge. MyJobQuote puts it at £400–£870 depending on the number of radiators, so ask whether it is included in your quote.
Sources
- New Boiler Installation Costs 2026: Prices by Type (heatable.co.uk)
- Combi Boiler Installation Cost Guide (UK Prices 2026) (myjobquote.co.uk)
- Boiler Service Cost: How Much is a Boiler Service in the UK? (myjobquote.co.uk)
- Power Flush Cost Guide (UK Prices 2026) (myjobquote.co.uk)
- Apply for the Boiler Upgrade Scheme: what you can get (gov.uk)
- Energy Company Obligation (ECO) (ofgem.gov.uk)
- Warm Homes: Local Grant (WH:LG) GM Wide Scheme (greatermanchester-ca.gov.uk)
- Home Energy Scotland Grant and Loan (homeenergyscotland.org)
Last checked: September 2026. Prices change with boiler models, labour rates and grant rules, so treat these as a guide and get written quotes.
Best Boiler Deals is a comparison and referral service, not a heating engineer. We do not install or repair boilers, and a listing here is not a recommendation.