Replacing your boiler is one of the biggest home improvement decisions you’ll make — and the costs can vary by thousands of pounds depending on the type, brand, and complexity of the installation. This guide breaks down every cost you need to budget for in 2026, from supply-only prices to full installation, conversions, and ancillary extras.
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- Gas combi boiler: £2,000–£3,500 installed - most cost-effective option for UK homes with mains gas access in 2026
- Heat pump: £7,000–£13,000 after £7,500 BUS grant - only consider if you’re planning for the 2035 gas boiler phase-out
- Installation takes 1–3 days for a like-for-like boiler swap - system changes or relocations can take 3–5 days and add £500–£1,500
- Get 3 Gas Safe registered quotes minimum - prices vary 30–50% for identical boilers depending on installer
- Annual servicing costs £80–£120 - mandatory to maintain manufacturer warranty and recommended for landlord gas safety compliance
How Much Does a New Boiler Cost in the UK?
A new boiler costs £1,500–£5,500 installed in the UK, depending on the type. A combi boiler (the most popular choice) averages £3,000–£3,800 including installation. Supply-only prices start from £600 for budget models, with installation labour adding £1,000–£2,000 on top.
A new boiler costs £1,500 to £5,500 fully installed in the UK, depending on the boiler type, brand, and installation complexity. Combi boilers are the most popular choice, averaging £2,000 to £3,500 installed, and suit most homes with one bathroom. System boilers cost £2,500 to £4,500 and are better for properties with multiple bathrooms, while regular boilers range from £2,000 to £4,000. Premium brands like Worcester Bosch and Vaillant sit at the higher end, while budget options from Ideal and Baxi start from around £1,500 installed.
The boiler itself typically accounts for 50 to 65 percent of the total cost, with labour, parts, and building regulations compliance making up the remainder. Replacing a like-for-like combi boiler is the cheapest installation type, while converting from a regular boiler to a combi adds £500 to £1,500 in additional pipework and system modification costs.
Boiler costs depend on three main factors: the type of boiler, the brand you choose, and the complexity of the installation. A straightforward like-for-like swap (same type, same location) is the cheapest option, while converting from one boiler type to another or relocating the unit adds significant cost.
| Boiler Type | Supply Only | Installed (Total) | Average |
|---|---|---|---|
| Combi | £600 – £4,000 | £1,500 – £4,500 | £3,000 – £3,800 |
| System | £500 – £3,000 | £1,600 – £5,000 | £3,300 |
| Conventional (Regular) | £500 – £3,500 | £1,600 – £5,500 | £3,550 |
| Electric | £500 – £3,800 | £1,500 – £5,000 | £3,250 |
| Oil | £1,000 – £4,500 | £2,300 – £6,000 | £4,150 |
These figures are based on consensus data from four leading UK boiler cost guides, verified in February 2026. All prices include VAT at the standard rate. Energy-saving installations may qualify for the reduced 0% VAT rate under the ECO4 scheme.
Combi Boiler Costs
Combi boilers cost £1,500–£4,500 installed, with most homeowners paying £3,000–£3,800. They’re the most popular choice in the UK (accounting for over 70% of new installations) because they heat water on demand without needing a separate tank or cylinder.
Combi boilers are ideal for small to medium homes (1–3 bedrooms, 1 bathroom) where hot water demand is moderate. They save space by eliminating the need for a hot water cylinder and cold water tank, making them popular for flats and terraced houses.
| House Size | Recommended Output | Supply Only | Installed |
|---|---|---|---|
| 1–2 bed flat | 18–27 kW | £600 – £1,700 | £1,500 – £2,650 |
| 3–4 bed house | 28–34 kW | £700 – £2,900 | £2,200 – £3,800 |
| 4+ bed house | 35–43 kW | £800 – £4,000 | £2,800 – £5,000 |
If your home has two or more bathrooms, a system boiler with a stored hot water cylinder is often a better choice than a high-output combi, as combis can struggle to supply multiple showers simultaneously.
System Boiler Costs
System boilers cost £1,600–£5,000 installed, averaging £3,300. They store hot water in a cylinder so they can supply multiple taps and showers at once — making them the best choice for larger homes with 2+ bathrooms.
System boilers work with a sealed heating system (no cold water tank in the loft) and a hot water cylinder, usually in an airing cupboard. The cylinder adds £300–£1,300 to the total cost if you’re converting from a combi, but most system-to-system swaps include the existing cylinder.
These boilers suit homes with 3–5 bedrooms and 2+ bathrooms. They’re also compatible with solar thermal panels, which can pre-heat the cylinder water and reduce gas bills by 10–15%.
Conventional (Regular) Boiler Costs
Conventional boilers cost £1,600–£5,500 installed, averaging £3,550. Also called regular or heat-only boilers, they use both a hot water cylinder and a cold water tank. They’re becoming less common but remain the best option for homes with existing gravity-fed systems and older pipework.
If your home already has a conventional boiler and you’re happy with the system, a like-for-like swap is the most cost-effective option. Converting to a combi or system boiler means removing the cold water tank and potentially re-routing pipework, which adds £800–£2,000 to the project.
Oil and Electric Boiler Costs
Oil boilers cost £2,300–£6,000 installed (averaging £4,150), while electric boilers range from £1,500–£5,000 (averaging £3,250). Oil boilers are common in rural areas without mains gas, and electric boilers are gaining popularity for flats and off-grid properties.
| Fuel Type | Installed Cost | Running Cost (p/kWh) | Annual Running Cost | Best For |
|---|---|---|---|---|
| Gas | £1,500 – £4,500 | 6.34p | £729 | Mains gas properties |
| Oil | £2,300 – £6,000 | 6.8p | £782 | Rural, off-grid homes |
| Electric | £1,500 – £5,000 | 24.86p | £2,859 | Flats, no gas supply |
| Biomass | £9,000 – £20,000 | 4–6p | £700 – £1,000 | Rural eco-homes |
Electric boilers are cheaper to install but significantly more expensive to run — up to 3.9 times the cost of gas per kWh. They’re most viable for well-insulated small properties or as secondary heating. Oil boilers have comparable running costs to gas but require a storage tank and regular fuel deliveries.
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New Boiler Prices by Brand
The six most popular boiler brands in the UK range from £600 for a budget Baxi combi to £4,000 for a premium Worcester Bosch model (supply only). Worcester Bosch and Vaillant dominate the market, while Ideal and Baxi offer the best value for budget-conscious buyers.
| Brand | Combi (Supply) | System (Supply) | Warranty | Market Position |
|---|---|---|---|---|
| Worcester Bosch | £600 – £4,000 | £800 – £2,500 | Up to 12 years | Premium, market leader |
| Vaillant | £900 – £3,700 | £700 – £2,200 | Up to 10 years | Premium, German-engineered |
| Viessmann | £1,050 – £3,500 | £1,000 – £2,800 | Up to 12 years | Premium, reliability-focused |
| Ideal | £650 – £2,500 | £600 – £2,000 | Up to 12 years | Mid-range, good value |
| Baxi | £600 – £2,500 | £500 – £1,800 | Up to 10 years | Budget-friendly |
| Alpha | £650 – £2,400 | £500 – £1,600 | Up to 7 years | Budget, compact range |
Worcester Bosch and Vaillant together account for over 60% of UK boiler installations. Both offer extended warranties of 10–12 years when installed by accredited engineers, which adds peace of mind but may limit your choice of installer. Budget brands like Baxi and Alpha offer reliable heating at a lower upfront cost, though warranties tend to be shorter.
For detailed brand analysis, see our Baxi Boilers review and Alpha Boilers review.
Installation and Labour Costs
Boiler installation labour costs £1,000–£2,000 on top of the boiler price. Gas engineers charge £300–£500 per day, with a straightforward like-for-like swap taking 4–8 hours and a conversion (e.g., regular to combi) taking 1–2 days.
| Installation Type | Typical Duration | Labour Cost | Notes |
|---|---|---|---|
| Like-for-like swap | 4–8 hours | £600 – £1,000 | Same type, same location |
| Conversion (reg to combi) | 1–2 days | £1,200 – £2,000 | Remove tank/cylinder, re-pipe |
| Relocation (same floor) | 1–1.5 days | £500 – £1,000 | New pipework, flue routing |
| Relocation (different floor) | 1.5–2 days | £1,000 – £1,500 | Major pipework changes |
| Back boiler removal | 2–3 days | £1,500 – £2,500 | Fireplace reinstatement needed |
All gas boiler installations must be carried out by a Gas Safe registered engineer. You can verify an engineer’s registration at gassaferegister.co.uk. OFTEC registration is required for oil boiler installations. Always ask for proof of registration before any work begins.
Boiler Conversion Costs
Converting from one boiler type to another costs £1,600–£6,500 including the new boiler. The most common conversion — regular to combi — averages £3,000–£4,000. Conversions cost more than like-for-like swaps because they require removing old tanks/cylinders and re-routing pipework.
| Conversion | Cost Range (Installed) | Average | What’s Involved |
|---|---|---|---|
| Conventional → Combi | £1,600 – £6,000 | £3,500 | Remove tank + cylinder, re-pipe, new flue |
| System → Combi | £1,600 – £5,500 | £3,200 | Remove cylinder, re-pipe |
| Conventional → System | £1,600 – £6,000 | £3,800 | Remove cold water tank, keep cylinder |
| Back boiler → Combi | £3,500 – £5,000 | £4,000 | Remove back boiler, reinstate fireplace, new location |
If you’re considering a conversion, think carefully about whether it’s worth it. Converting from a regular boiler to a combi saves loft and cupboard space, but if your home has 2+ bathrooms, you may be better off staying with a system or conventional setup. A combi boiler supplying two showers simultaneously will struggle to maintain pressure and temperature.
Additional Costs to Budget For
Beyond the boiler and labour, expect to budget £250–£1,500 for extras depending on what your installation needs. The most common additional costs are power flushing (£450–£800), a magnetic filter (£100–£300), and a smart thermostat (£100–£300).
| Additional Item | Cost | When Needed |
|---|---|---|
| Power flush | £450 – £800 | Recommended for systems 10+ years old |
| Magnetic filter (MagnaClean) | £100 – £300 | Strongly recommended — protects new boiler |
| Smart thermostat | £100 – £300 | Optional but can save 10–15% on heating bills – pair with new double glazing for maximum efficiency |
| Vertical flue extension | £300 – £600 | If boiler is far from an external wall |
| Plume management kit | £90 – £130 | Required if flue is near a window or walkway |
| Hot water cylinder | £300 – £1,300 | New or replacement for system/conventional boilers |
| Radiator replacement (each) | £80 – £200 | If existing radiators are undersized or corroded |
| Moving the boiler | £500 – £1,500 | Relocating to a different room or floor |
| Gas pipe upgrade | £100 – £400 | If existing pipe diameter is insufficient |
| Asbestos removal | £200 – £500 | Pre-1980s properties with boiler cupboard insulation |
A magnetic filter (£100–£300) is one of the best investments you can make during a boiler installation. It captures metallic debris from your heating system before it reaches the boiler, significantly reducing the risk of breakdowns. Most manufacturers now require one to validate their warranty.
For more on smart thermostats, see our guide to the best smart thermostats for boilers.
New Boiler Cost by Property Type
A new combi boiler costs around £2,000–£2,800 for a 1–2 bed flat, rising to £4,500–£7,000 for a 5-bed detached house (which typically needs a system boiler with cylinder). These are fully installed prices including labour and basic ancillaries.
| Property Type | Best Boiler Type | Output | Typical Installed Cost |
|---|---|---|---|
| 1–2 bed flat | Combi (24–27 kW) | 24–27 kW | £2,000 – £2,800 |
| 2–3 bed terrace | Combi (28–30 kW) | 28–30 kW | £2,500 – £3,500 |
| 3 bed semi-detached | Combi (30–35 kW) | 30–35 kW | £3,000 – £4,000 |
| 4 bed detached | System (18–25 kW) | 18–25 kW | £3,500 – £5,500 |
| 5+ bed detached | System (25–35 kW) | 25–35 kW | £4,500 – £7,000 |
These estimates assume a straightforward like-for-like replacement. Add £800–£2,000 if you’re converting boiler types, and £500–£1,500 if the boiler needs relocating. Properties with restricted access (e.g., basement installation, external wall limitations) may incur additional labour charges.
How to Reduce Your Boiler Replacement Costs
You can save £500–£2,000 on a new boiler by getting multiple quotes, choosing a mid-range brand, timing your purchase for off-season (spring/summer), and checking whether you qualify for a government grant covering part or all of the cost.
Get at least 3 quotes. Prices vary significantly between installers, even for the same boiler model. The cheapest quote isn’t always best — check Gas Safe registration, warranty terms, and whether the price includes a magnetic filter and system flush.
Consider timing. Installers are busiest from October to February when boilers fail during cold weather. Booking your replacement in spring or summer (March–July) can save 10–15% as demand drops and installers offer discounts to fill their schedule.
Choose the right size. An oversized boiler wastes money upfront and in running costs. A qualified engineer will calculate the correct output (in kW) based on your property’s radiator count, number of bathrooms, and heat loss profile.
UK Government Boiler Grants and Schemes
Several government schemes can help cover the cost of a new boiler, including the Boiler Upgrade Scheme (£7,500 towards heat pumps) and ECO4 (free or heavily subsidised boilers for low-income households). Eligibility depends on your property, income, and the type of heating system you’re installing.
| Scheme | Grant Value | Eligibility | Coverage |
|---|---|---|---|
| Boiler Upgrade Scheme (BUS) | £7,500 | Homeowners replacing fossil fuel heating with heat pump | England & Wales |
| ECO4 | Up to 100% (means-tested) | Low-income households, benefits recipients | Great Britain |
| Warm Home Discount | £150 rebate | Pension credit or low-income recipients | England & Wales |
| Warmer Homes Scotland | Up to 100% | Homeowners on qualifying benefits | Scotland |
| NISEP | Varies | Priority and non-priority customers via energy supplier | Northern Ireland |
| Boiler on Prescription | Varies by local authority | GP referral for health conditions worsened by cold homes | Select English councils |
The Boiler Upgrade Scheme (BUS) is the most significant grant available, but it only applies to heat pump installations, not gas boiler replacements. If you’re replacing a gas boiler with a new gas boiler, ECO4 is the main route to financial support — but it’s means-tested and typically only available to households receiving certain benefits.
For the full list of eligibility criteria and how to apply, see our UK boiler grants guide.
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Energy Savings from Replacing Your Boiler
Upgrading from an old G-rated boiler to a new A-rated condensing boiler can save up to £490 per year on energy bills for a detached house. Even upgrading from a D-rated boiler saves £170–£220 per year. Payback periods range from 5–15 years depending on your current boiler’s efficiency.
| Old Boiler Rating | Efficiency | Annual Saving (Semi) | Annual Saving (Detached) | Payback (at £3,500) |
|---|---|---|---|---|
| G (very old) | Below 70% | £385 | £490 | 7–9 years |
| F | 70–74% | £275 | £340 | 10–13 years |
| E | 74–78% | £220 | £270 | 13–16 years |
| D | 78–82% | £170 | £220 | 16–21 years |
Energy savings data is based on figures from the Energy Saving Trust for a gas boiler upgrade. Actual savings depend on your insulation levels, thermostat settings, and how you use heating. Adding a smart thermostat can increase savings by a further 10–15%.
Regional Pricing Variations
Boiler installation costs vary by up to 25% across UK regions. London and the South East are the most expensive (15–25% above average), while Wales, the North East, and Scotland tend to be 5–10% below the national average. These differences are driven by labour rates, not boiler prices.
| Region | vs National Average | Typical Combi Installed |
|---|---|---|
| London | +20–25% | £3,600 – £4,750 |
| South East | +10–15% | £3,300 – £4,350 |
| South West | +5–10% | £3,150 – £4,200 |
| Midlands | Baseline | £3,000 – £3,800 |
| North West | -5% | £2,850 – £3,600 |
| North East | -5–10% | £2,700 – £3,400 |
| Scotland | +5% | £3,150 – £4,000 |
| Wales | -5–10% | £2,700 – £3,400 |
These regional differences reflect labour costs rather than equipment prices. A Worcester Bosch Greenstar 30i costs the same to buy regardless of location, but the engineer fitting it in Central London charges significantly more per day than one in Newcastle. Getting quotes from local installers is the only reliable way to establish your actual costs.
Boiler vs Heat Pump: Cost Comparison
An air source heat pump costs £8,000–£15,000 installed (or £500–£7,500 after the BUS grant), compared to £1,500–£4,500 for a gas combi boiler. Heat pumps have lower running costs (2–4x more efficient) but higher upfront costs. The government plans to phase out new gas boilers by 2035.
| Factor | Gas Combi Boiler | Air Source Heat Pump |
|---|---|---|
| Installed cost | £1,500 – £4,500 | £8,000 – £15,000 |
| After BUS grant | No grant available | £500 – £7,500 |
| Annual running cost | £729 | £500 – £800 |
| Efficiency | 90–94% | 250–400% (COP) |
| Lifespan | 10–15 years | 20–25 years |
| Maintenance | £80–£120/year service | £100–£200/year service |
| Space needed | Wall-mounted (minimal) | Outdoor unit + indoor cylinder |
| Future-proofing | Gas boiler ban from 2035 | Government-supported, long-term |
If your current boiler has failed and needs immediate replacement, a gas boiler is still the most practical and affordable option for most UK homes. However, if you’re planning ahead and your property is well-insulated with adequate outdoor space, an air source heat pump with the £7,500 BUS grant can be cost-competitive over its 20–25 year lifespan.
For full heat pump pricing, see our solar panel costs guide and biomass boiler guide.
Signs You Need a New Boiler
The average boiler lasts 10–15 years. If yours is approaching that age and showing signs of inefficiency, frequent breakdowns, or strange noises, it’s usually more cost-effective to replace than repair. A single major repair can cost £300–£500 — money better put towards a new boiler with a 10–12 year warranty.
Replace your boiler if you notice:
- Rising energy bills — older boilers lose efficiency as heat exchangers corrode. A 15-year-old boiler may operate at 70–80% efficiency vs 90–94% for a new A-rated model.
- Frequent breakdowns — if you’re calling an engineer more than once a year, repair costs will quickly exceed replacement.
- Yellow or orange flame — a healthy boiler flame is blue. Yellow/orange indicates incomplete combustion and potential carbon monoxide risk. Get this checked immediately.
- Strange noises — banging, whistling (kettling), or gurgling often indicate limescale build-up or failing components.
- Radiators slow to heat — if some rooms take a long time to warm up, your boiler may lack the output for your property.
- Leaking or dripping — internal corrosion causing leaks is usually terminal for the boiler.
- Replacement parts unavailable — manufacturers typically support parts for 10–15 years. After that, repairs become increasingly difficult and expensive.
For more on servicing and maintenance costs, see our boiler service costs guide.
How to Choose a Boiler Installer
Always use a Gas Safe registered engineer for gas boiler installations — it’s a legal requirement. Get at least 3 written quotes, check for manufacturer accreditation (which extends warranties), and never pay more than 25% as a deposit.
Checklist for choosing an installer:
- Gas Safe registered — verify at gassaferegister.co.uk. This is legally required for any gas work.
- Manufacturer accredited — Worcester Bosch Accredited Installers, Vaillant Advance, Viessmann Trained, etc. This can extend your warranty from 5 years to 10–12 years.
- Written quote — includes boiler model, output, all ancillaries, timeline, total cost, and payment terms.
- Insurance — public liability and professional indemnity insurance.
- Reviews — check Trustpilot, Google reviews, or Checkatrade ratings.
- Deposit limits — never pay more than 25% upfront. Reputable installers typically require no deposit at all or a small booking fee.
- Building regulations notification — the installer must notify your local building control through the Gas Safe or Competent Persons scheme.
For a curated list of boiler types and brands, see our best combi and condensing boilers guide.
For a full overview of heating options and costs, see our complete guide to boilers. Unsure which type suits your home? Our guide to combination boiler benefits can help you decide.
