New Boiler Cost by Type & House Size (2026 UK)
A new boiler costs from £1,380 for a like-for-like combi swap in 2026, with most homeowners paying £1,380-£2,200 installed. A system boiler runs £1,880-£3,000, and converting a conventional or system setup to a combi costs £2,820-£4,500. The boiler unit itself is typically only 40-60% of the bill; the rest is labour, flue, magnetic filter, system flush and controls. This guide breaks down Q3 2026 installed prices by boiler type, house size, brand tier and running costs, using verified quotes across 519 UK towns.
- Like-for-like combi swaps from £1,380
- Priced from our live 519-town dataset
- Gas Safe registered engineers only
- Free quotes, no obligation
How Much Does a New Boiler Cost? Quick Answer
In 2026 a straightforward like-for-like combi swap costs from £1,380, with a typical installed range of £1,380-£2,200 depending on region and brand tier. A system boiler costs £1,880-£3,000 installed, while converting from a conventional or system setup to a combi costs £2,820-£4,500 and usually takes two days. The boiler unit itself is only 40-60% of the price; labour (1-3 days), the flue, a magnetic filter, a system flush and controls make up the rest.
For town-by-town figures see our full boiler replacement cost guide, or get a tailored estimate in under a minute with the boiler cost calculator.
Jump to: Cost by boiler type · Cost by house size · What's included · Brand tiers · Running-cost savings · What affects the price · How to save · Free quotes · FAQs
New Boiler Cost by Type (2026 Installed Prices)
The single biggest driver of boiler installation cost is the type of job, not the badge on the front. A like-for-like swap (combi for combi, heat-only for heat-only) keeps the existing pipework, flue position and system layout, so labour stays close to one day. Change the system type and the price climbs quickly: converting to a combi means stripping out tanks and the cylinder, rerouting pipework and often upgrading the gas supply pipe, which adds at least a full extra day of labour and several hundred pounds of materials.
| Job type | Installed cost (2026) | Typical duration | Best for |
|---|---|---|---|
| Like-for-like combi swap | £1,380-£2,200 | 1 day | Homes with an existing combi; the cheapest and most common boiler job in the UK |
| Heat-only (regular) boiler, like-for-like | £1,550-£2,500 | 1 day | Homes keeping the loft tanks and hot water cylinder, often with older radiator systems |
| System boiler, like-for-like | £1,880-£3,000 | 1-1.5 days | Larger homes with a cylinder and two or more bathrooms; no loft tanks needed |
| Conventional or system to combi conversion | £2,820-£4,500 | 2 days | Freeing up the airing cupboard and loft; smaller households with one bathroom |
| Back boiler to combi conversion | £3,500-£5,500 | 2-3 days | Replacing an old fireplace back boiler; the most disruptive job on this list |
Across every job type the boiler unit itself is typically 40-60% of the installed price. On a £1,800 combi swap that means roughly £700-£1,100 for the boiler and the balance for labour, the flue kit, a magnetic filter, a system cleanse and controls. This is why two quotes for the same boiler model can differ by hundreds of pounds: you are really comparing the installer's labour, materials and margin.
A note on scope: these figures are for mains gas boilers, which heat the large majority of UK homes. Oil and LPG boilers, and electric boilers, price differently and are not covered by the ranges on this page.
New Boiler Cost by House Size
House size matters less for the installation labour and more for the boiler you should buy. For a combi, the kW rating is mostly about hot water performance at the tap, not radiator count: a bigger combi heats water faster for showers and baths. For heating alone, even a large house rarely needs more than 20kW of boiler output once insulation is accounted for, which is why a decent installer sizes from a heat loss calculation rather than a bedroom count. Use the table below as a sanity check, not a substitute for a survey.
| House size | Recommended boiler | Output (kW) | Installed cost (2026) |
|---|---|---|---|
| 1-2 bed flat | Combi | 24-27kW | £1,380-£1,800 (like-for-like swap) |
| 3-bed semi | Combi | 28-32kW | £1,500-£2,200 (like-for-like swap) |
| 4-bed house | Large combi or system boiler | 32-36kW | £1,700-£3,000 depending on type |
| 5+ bed house | System boiler with unvented cylinder | 35kW+ | £1,880-£3,000, plus £1,200-£2,000 if the cylinder is replaced |
Two practical rules sit behind these recommendations. First, combis draw hot water straight from the mains, so they need reasonable mains pressure and flow (roughly 10 litres per minute or better) to perform; a weak supply strangles even a 36kW combi. Second, homes with two or more bathrooms in regular use are usually better served by a system boiler and cylinder, because stored hot water can feed several outlets at once without the flow dropping. Oversizing a combi "to be safe" simply wastes money upfront and causes short-cycling on heating, so treat any quote that skips these questions with caution.
What a New Boiler Quote Should Include, Line by Line
A professional written quote is itemised, and comparing quotes line by line is the fastest way to spot padding. Here is what a complete installation covers and what each line typically costs within the total.
| Line item | Typical cost within the quote | Notes |
|---|---|---|
| Boiler unit | £600-£1,600 | 40-60% of the installed price; varies by tier and output |
| Flue kit | £100-£200 | Standard horizontal flue; vertical flues add roughly £150-£300, plume kits extra |
| Magnetic system filter | £100-£150 fitted | Protects the heat exchanger; many manufacturers require one for extended warranties |
| System cleanse and inhibitor | £80-£150 | Chemical flush is the minimum; a power flush (£300-£600) only if the system is sludged |
| Controls | £80-£250 | Wireless room thermostat at minimum (a Building Regs requirement); smart thermostats at the top end |
| Labour | £350-£600 per day | 1 day for a swap, 2 days for a conversion, 2-3 days for a back boiler job |
| Gas Safe notification + Building Regs certificate | Usually included (£0-£80) | Installer notifies Building Control via Gas Safe; certificate posted to you |
Beyond the lines above, expect the engineer to leave you a completed Benchmark commissioning checklist in the boiler manual and to register the warranty with the manufacturer, normally within 30 days of installation. The Building Regulations compliance certificate arrives by post a few weeks after the Gas Safe notification. Keep all three documents: solicitors ask for the certificate when you sell, and manufacturers ask for the Benchmark record and annual service history before honouring warranty claims.
If a quote is a single round number with no breakdown, ask for the itemised version. Any installer confident in their pricing will provide it.
Boiler Brands: Budget, Mid-Range and Premium Tiers
We deliberately do not publish per-brand installed prices. The same boiler model can be quoted hundreds of pounds apart depending on the installer's buying terms, your region and the week of the year, so brand price lists age badly and mislead. What holds true is the tier structure: the market splits into budget, mid-range and premium bands, with predictable differences in installed-price uplift and warranty length.
| Tier | Typical installed-price uplift | Typical warranty | What you get |
|---|---|---|---|
| Budget | Baseline (the lowest installed prices) | 5-7 years | Does the job; simpler components and shorter cover. A reasonable fit for rentals or short-term ownership |
| Mid-range | +£100-£300 over budget | 7-10 years | The value sweet spot for most homes; proven platforms, parts available everywhere, solid warranty terms |
| Premium | +£300-£700 over budget | 10-12 years | Stainless steel heat exchangers, quieter running, the longest warranties, typically via manufacturer-accredited installers |
The most useful way to compare tiers is warranty per pound. Moving from a 5-7 year warranty to a 10-12 year warranty for a few hundred pounds effectively caps your repair bills for a decade, which is strong value on a £1,500-£2,000 purchase. Two caveats apply across every tier: the long headline warranties usually require the boiler to be fitted by an installer accredited by that manufacturer, and every warranty depends on an annual service by a Gas Safe registered engineer, typically £80-£120 a year. Miss a service and the cover can lapse regardless of brand.
Running Costs: Old G-Rated vs New A-Rated Boiler
An old G-rated boiler converts roughly 70% or less of the gas it burns into useful heat; a modern A-rated condensing boiler achieves 92-94%. Swapping one for the other cuts the gas used for heating and hot water by about a fifth to a quarter. The table below shows what that is worth per year at typical usage bands and 2026 unit rates.
| Home | Typical annual gas use | Estimated annual saving (G-rated to A-rated) |
|---|---|---|
| 1-2 bed flat | ~8,000 kWh | £120-£180 |
| 3-bed semi | ~11,500 kWh | £180-£260 |
| 4-bed detached | ~17,000 kWh | £270-£390 |
| Large 5+ bed home | ~23,000 kWh | £360-£530 |
Treat these as planning figures, based on typical medium usage patterns for each home size. Your actual saving depends on how inefficient the outgoing boiler really was, how you heat your home, and your tariff. Controls stretch the saving further: a smart thermostat with weather compensation, plus thermostatic radiator valves, lets a modern boiler run in condensing mode more of the time, which is where the efficiency gains live.
If you are weighing up repair versus replace, our guide on how long a boiler lasts in the UK covers the warning signs that matter more than age alone: repair frequency, heat exchanger condition and pressure loss.
What Affects New Boiler Installation Cost
1. The type of job
As the flagship table shows, a like-for-like swap and a conversion to combi can be £2,000+ apart for the same house. Keeping the new boiler in the same place, on the same system type, is the single biggest cost saver there is.
2. Boiler output and tier
A 36kW premium combi can cost £500-£900 more installed than a 26kW budget model. Pay for output you will use (hot water performance) and warranty you value, not for headroom on paper.
3. Moving the boiler
Relocating a boiler to the kitchen, garage or loft adds pipework, flue work and making good, typically £300-£800 on top of the ranges above. Relocations often ride along with bigger projects; if your swap is part of one, our house extension cost guide and extension cost calculator cover the wider budget.
4. Flue and condensate runs
A standard horizontal flue through the wall is included in most quotes. A vertical flue through the roof adds roughly £150-£300, plume management kits add more, and a long condensate run to a drain (or a condensate pump where gravity will not do) adds labour and materials.
5. The state of the existing system
Sludged radiators force a power flush (£300-£600). Old microbore or corroded pipework may need upgrading, and a combi conversion often requires the gas supply pipe upsized to feed the higher-output boiler. Radiator and TRV replacements are worth doing while the system is drained, but they add to the bill.
6. Region and access
London and the South East carry the highest labour rates in the UK, while awkward access (flats above ground floor, permit parking, long carries) adds time. See the regional note below for how much this moves the total.
7. Time of year
Boiler demand peaks from September to February, when breakdowns spike and installers' diaries fill. Distress purchases in the cold months leave no room to compare quotes or negotiate; a planned swap in spring or summer almost always prices better.
How to Save Money on a New Boiler
- Get at least three itemised quotes. Spreads on identical jobs routinely run £300-£600. Our free boiler quotes service matches you with vetted Gas Safe installers so you can compare like for like.
- Buy in spring or summer. Beat the September-to-February rush: shorter lead times, keener prices, and no days without heating while you wait.
- Stay like-for-like where it makes sense. Same boiler type, same position is the cheapest job on the board. Only pay for a conversion if the combi benefits (space, no tanks, mains-pressure hot water) genuinely matter to you.
- Pick mid-tier with a 7-10 year warranty. That combination is the best value for most homes; pay the premium uplift only if you want the 10-12 year cover.
- Use a manufacturer-accredited installer. The same boiler often comes with 2-5 extra warranty years at no extra cost, purely because of who fits it.
- Right-size, don't oversize. A 30kW combi that fits your hot water demand beats a 36kW "just in case" unit that costs more and short-cycles.
- Question default extras. A power flush belongs on the quote only when the system shows sludge symptoms; a chemical cleanse is otherwise sufficient (and required for the warranty).
- Check ECO4 eligibility before paying privately. Low-income households receiving qualifying benefits may get a broken or very old boiler replaced under the scheme.
Before committing, sanity-check your numbers against your own home's details with our boiler cost calculator; it takes under a minute and reflects the same 519-town dataset behind this guide.
Regional Price Differences
Labour is the swing factor. London and the South East typically price 20-30% above the cheapest UK regions, consistent with our UK home improvement cost index. In practice that means the £1,380 like-for-like combi swap available in the cheapest areas becomes roughly £1,700-£2,200 for the same boiler and the same day's work in London. The North East, Yorkshire and much of Wales and Northern Ireland sit at the affordable end; the South East, and London in particular, anchor the top.
Materials barely move between regions; the boiler costs what it costs. So the further your quotes sit above the ranges on this page, the more you are paying for local labour rates and demand, and the more worthwhile it is to compare several installers rather than accept the first figure. Town-level prices for your area are in our boiler replacement cost guide.
Once you know which boiler type you need, compare manufacturers in our guide to the best boiler brands in the UK 2026 — installed price bands, warranty cover and head-to-heads.
FAQs
In 2026 a like-for-like combi swap costs from £1,380, with most installations landing between £1,380 and £2,200 depending on region and brand tier. A system boiler costs £1,880-£3,000 installed, and converting a conventional or system setup to a combi costs £2,820-£4,500. The boiler unit itself is typically 40-60% of the installed price; the rest covers labour over 1-3 days, the flue, a magnetic filter, a system flush and controls. All figures include VAT at 20%.
A like-for-like combi swap, replacing an existing combi with a new one in the same position, costs £1,380-£2,200 installed in 2026. It is the cheapest and quickest boiler job because the pipework, flue route and system layout stay the same, so labour is usually a single day. In the cheapest UK regions a straightforward swap starts at £1,380; in London and the South East expect roughly £1,700-£2,200 for the same job. Converting from a conventional or system boiler to a combi is a much bigger job at £2,820-£4,500.
For a typical 3-bed semi, a 28-32kW combi swap costs around £1,500-£2,200 installed in 2026. If the house has a conventional boiler with loft tanks and you want to move to a combi, budget £2,820-£4,500 for the conversion. If you would rather keep stored hot water, a like-for-like system boiler is £1,880-£3,000. Most 3-bed installations take one day for a swap and about two days for a conversion.
A like-for-like swap normally takes one day. A system boiler with cylinder work can stretch to a day and a half. Converting a conventional or system setup to a combi usually takes two days, because the tanks and cylinder come out and pipework is rerouted. A back boiler to combi conversion is the biggest job at two to three days, involving removal of the old unit from the fireplace, capping off, new pipe runs and making good. Add time if a power flush or radiator changes are on the schedule.
A conversion is priced at £2,820-£4,500 because it re-engineers the heating system rather than just changing the box on the wall. The engineer removes the loft tanks and hot water cylinder, reroutes hot and cold pipework, often upsizes the gas supply pipe to feed a higher-output combi, runs a new condensate pipe, moves or replaces the flue and makes good afterwards. That adds at least a full extra day of labour plus materials on top of the boiler itself.
As a guide: a 1-2 bed flat suits a 24-27kW combi, a 3-bed semi a 28-32kW combi, and a 4-bed house a 32-36kW combi or a system boiler. For combis the rating is mostly about hot water speed at the tap, not radiator count, and they need decent mains pressure and flow (roughly 10 litres per minute or better) to perform. Homes with two or more bathrooms in regular use are usually better served by a system boiler with a cylinder. A good installer sizes from a heat loss calculation; be wary of anyone quoting a size without asking about radiators, bathrooms and mains flow.
Often, yes, but not automatically. A well-serviced 15-year-old boiler may still be safe, yet it typically runs at 80-85% efficiency or lower against 92-94% for a new A-rated model, and parts get scarcer and dearer with age. A common rule of thumb: if an out-of-warranty boiler needs a repair over roughly £350-£500, put that money towards replacement instead. Age alone is not the whole story; our guide on how long a boiler lasts in the UK covers the signals that matter, like repair frequency, heat exchanger condition and pressure loss.
Frame it as warranty per pound. Premium-tier boilers typically add £300-£700 to the installed price but carry 10-12 year warranties when fitted by a manufacturer-accredited installer, plus better heat exchangers and quieter running. Mid-range models at +£100-£300 with 7-10 year warranties are the sweet spot for most homes. Budget models with 5-7 year cover suit rentals or short-term ownership. Whatever the tier, the warranty normally depends on registration within 30 days and an annual service, so budget £80-£120 a year for that.
Replacing an old G-rated boiler (roughly 70% efficient or less) with a new A-rated condensing model (92-94%) cuts the gas used for heating and hot water by about a fifth to a quarter. Based on typical medium usage and 2026 unit rates, that works out at roughly £120-£180 a year for a 1-2 bed flat, £180-£260 for a 3-bed semi and £270-£390 for a 4-bed detached home. Actual savings depend on how inefficient the old boiler was, your usage and your controls; a smart thermostat and TRVs stretch the saving further.
Not always. Every professional installation should include at least a chemical cleanse and fresh inhibitor (typically £80-£150 within the quote). A full power flush at £300-£600 is only needed where the system shows real sludge symptoms: cold patches at the bottom of radiators, dirty black water, kettling noises. Be wary of it appearing on every quote as a default extra. Do insist on a magnetic system filter (£100-£150 fitted); many manufacturers require one, plus evidence of cleansing, for the long warranty to hold.
The prices in this guide include VAT at 20%, and reputable written quotes should too; always check the wording. Your installer must be Gas Safe registered, and after installation they notify Building Control through the Gas Safe scheme, which triggers a Building Regulations compliance certificate posted to you within a few weeks. You should also receive a completed Benchmark commissioning checklist in the boiler manual. Keep both: solicitors ask for the certificate when you sell, and manufacturers ask for the Benchmark record for warranty claims.
Support exists but is narrow. The ECO4 scheme can fund boiler replacement for eligible low-income households, generally those receiving qualifying benefits in less efficient homes, and mainly where the existing boiler is broken or very old. Most homeowners pay privately. Many installers offer finance ranging from 0% promotional deals to 10%+ APR, so compare the total repayable rather than the monthly figure. Avoid paying the full balance upfront; a deposit with the balance on completion is normal practice.
Ready to Price Your New Boiler?
Tell us about your home once and get up to three itemised quotes from Gas Safe registered installers near you. Compare them line by line against the prices in this guide, then pick the best value or walk away. It is free and there is no obligation.
One timing tip: boiler demand peaks from September to February. Booking before autumn usually means shorter waits, sharper prices and a planned swap on your terms rather than a cold-snap emergency.