The short answer
A new combi boiler costs £1,500–£3,500 supply and fit in most UK homes; system and regular boiler replacements with a new cylinder typically cost £2,000–£4,500. Budget, mid-range and premium models, boiler size, location and any pipework changes are the main variables. See the installation cost breakdown for a line-by-line guide to what you are paying for.
A boiler is one of the most significant single purchases most UK homeowners make, and the range of prices online — from under a thousand pounds to over five thousand — can make it hard to know what is reasonable. This guide sets out realistic 2026 supply-and-fit ranges for the three main boiler types, explains what drives the differences, and flags the scenarios that push costs up so there are no surprises in a quote.
New boiler costs at a glance
- Budget combi (supply & fit) £1,500–£2,200
- Mid-range combi (supply & fit) £2,200–£3,000
- Premium combi (supply & fit) £3,000–£3,500+
- System boiler + cylinder £2,000–£4,500
- Regular boiler + cylinder £2,000–£4,000
- Conversion extra (to combi) £300–£700 additional
Combi boiler supply-and-fit costs
For most UK homeowners, a like-for-like combi replacement is the most straightforward installation. Budget-tier boilers from lesser-known brands — or well-known brands’ entry-level models — typically cost £700–£1,000 for the unit alone; mid-range models from Worcester Bosch, Vaillant, Ideal and Baxi sit between £900–£1,400; premium and high-output models reach £1,300–£1,800 or more. Labour for a standard like-for-like swap in a single day is typically £500–£800 for an experienced Gas Safe engineer or £600–£1,000 for a larger firm. Parts, fittings and the Benchmark commissioning certificate add a further £100–£200. The all-in supply-and-fit figure therefore lands between £1,500 and £3,500 for the large majority of combi replacements, with location (London and South-East costs are typically 10–20% higher) and access conditions being the main local variables.
| Boiler tier | Unit cost (approx.) | Installed (supply & fit) |
|---|---|---|
| Budget | £700–£950 | £1,500–£2,200 |
| Mid-range | £950–£1,400 | £2,200–£3,000 |
| Premium | £1,400–£1,800 | £3,000–£3,500+ |
System and regular boiler costs
A system boiler replacement requires installing or replacing the cylinder as well as the boiler itself. A standard 150–200 litre unvented cylinder costs £400–£700 supplied; a larger or premium model costs more. The boiler unit is similar in cost to a combi of the same brand and output. Together, a system boiler and cylinder installation typically costs £2,000–£4,500 depending on the boiler tier, cylinder specification and how much pipework adjustment is needed. A regular boiler replacement follows a similar cost profile if the existing cylinder and loft tank are retained; replacing them adds to the bill. For the detail on what each line in a quote represents, see our installation cost breakdown.
What pushes costs up
Several scenarios can push a boiler installation above the typical ranges:
- Converting boiler type — switching from a regular boiler to a combi means removing the cylinder and loft tank and re-routing pipework: typically £300–£700 extra. See our conversion cost guide.
- Moving the boiler — relocating the boiler to a different room or wall adds pipework and flue work, typically £300–£1,000 depending on distance. See our boiler relocation guide.
- Power flush — if the system contains significant sludge, a power flush before installation protects the new boiler: typically £300–£500. See our guide on whether you need a power flush.
- Flue extension or rerouting — non-standard flue routes add material and labour costs.
- Magnetic filter and inhibitor — typically £80–£150 for the filter plus fluid, but often included by better installers as standard.
Boiler warranty and what it adds
Manufacturer warranties on new boilers typically run 2–10 years depending on brand and model. Worcester Bosch and Vaillant both offer up to 10-year warranties on some models when installed by their accredited engineers. Extended warranties add value because the heat exchanger — the most expensive component to replace — is covered. Some installers include an extended warranty as part of a package price; others charge a separate premium. The cost of a 5–10 year parts-and-labour warranty is typically £150–£350 if purchased separately, and is worth considering for a mid-range or premium boiler. See our guide on what warranty you should look for.
Boiler finance and grants
If the upfront cost is a concern, many installers offer finance plans that spread the cost over 12–60 months. The Boiler Upgrade Scheme (BUS), administered by Ofgem, offers grants for replacing gas boilers with heat pumps rather than like-for-like gas replacements — £7,500 for an air-source heat pump and £7,500 for a ground-source heat pump at the time of publication. If you are on certain benefits, you may be eligible for a free or subsidised boiler under the Energy Company Obligation (ECO4) scheme. See our boiler grants guide for the current eligibility rules. This is general information; costs vary with your specific home and the quotes you receive, and all gas work must be done by a Gas Safe registered engineer.
Compare new boiler quotes
Prices vary significantly between installers for the same boiler and job. Use our service to compare quotes from Gas Safe registered engineers in your area.
Frequently asked questions
What is the average cost of a new boiler fitted in the UK?
A like-for-like combi boiler replacement typically costs £1,500–£3,500 supply and fit in 2026. System boiler replacements including a new cylinder typically cost £2,000–£4,500. The range reflects boiler brand, output, location and the complexity of the installation.
How much does a Worcester Bosch boiler cost to install?
A Worcester Bosch Greenstar combi, one of the UK’s most popular ranges, typically costs £900–£1,400 for the unit. Installed by an Accredited Installer, the supply-and-fit total is typically £2,200–£3,200, with a 10-year warranty available through Worcester Bosch’s accredited network.
Is it cheaper to repair or replace a boiler?
As a general rule, if repair costs exceed one-third of the replacement cost and the boiler is over 10 years old, replacement is often more cost-effective in the long run. A Gas Safe engineer can advise on the condition of your boiler and whether it is worth repairing.
Can I get a free boiler in the UK?
Free or heavily subsidised boilers are available through the ECO4 scheme for households on qualifying benefits. The Boiler Upgrade Scheme (BUS) offers grants toward heat pumps rather than replacement gas boilers. See our boiler grants guide for current eligibility.
Sources & further reading
- Gas Safe Register — guidance on boiler installation and finding registered engineers
- Energy Saving Trust — boiler replacement costs and energy efficiency
- GOV.UK — Boiler Upgrade Scheme (BUS) and ECO4 scheme eligibility
- GOV.UK / Building Regulations Approved Document L — boiler efficiency standards for new installations
This is general information, not advice for your specific property or installation. Costs, timescales and outcomes vary with your home, system condition and chosen engineer. All gas boiler work must be carried out by a Gas Safe registered engineer.