New boiler cost: what a replacement really runs to in 2026
Installed 2026 prices for combi, system and regular boilers, what converting to a combi adds, boiler prices by brand, and the lines a full quote should carry.
A new boiler costs £1,800 to £3,500 fitted in 2026 when a combi replaces a combi in the same spot, and £2,500 to £4,000 covers most UK boiler jobs. The job sets the price more than the boiler does. We give installed prices by boiler type, what converting to a combi adds, unit prices by brand, what a full quote includes, and where grants still apply.
New boiler cost by type
These are 2026 installed prices: the boiler, the fitting, the flue and the standard parts, for a new boiler going where the old one was. Moving it to another room is extra and gets priced after a survey.
| Job | Installed price | What the price assumes |
|---|---|---|
| Like-for-like combi swap | £1,800 – £3,500 | Combi replaces combi in the same place |
| Premium combi swap | £3,000 – £4,500 | Higher-spec model with a longer guarantee |
| System boiler replacement | £1,800 – £3,500 | Existing hot water cylinder kept |
| Regular (heat-only) boiler replacement | £1,800 – £3,000 | Loft tank and cylinder kept |
| Regular or system to combi | £3,000 – £5,700 | Tank and cylinder taken out |
| Back boiler to combi | £3,500 – £6,000 | Back boiler removed, new boiler fitted elsewhere |
Combi boiler cost
A combi heats water on demand from the mains, so there is no tank or cylinder to replace. That keeps a like-for-like swap simple: £1,800 to £3,500 fitted, and a day's work.
Fixed-price quotes for a straight combi swap cluster around £2,500 in 2026. Worcester Bosch lists its Greenstar 2000 30kW at an indicative £2,475 fitted, including VAT. The premium band, £3,000 to £4,500, buys a higher-spec boiler and a longer guarantee for the same amount of work.
System boiler cost
A system boiler heats a hot water cylinder, usually in an airing cupboard, and needs no tank in the loft. Replacing the boiler and keeping the cylinder costs £1,800 to £3,500 fitted. A new cylinder on the same visit is extra, and a good quote prices it as its own line.
Regular boiler cost
A regular boiler, also sold as heat-only or conventional, works with a cold water tank in the loft and a hot water cylinder. Swapping the boiler alone, with the tank and cylinder kept, costs £1,800 to £3,000 fitted. For a home already set up for stored hot water, that is the cheapest route.
Back boiler replacement cost
A back boiler sits behind a gas fire in the chimney breast. Taking it out and fitting a combi in another room costs £3,500 to £6,000, because the old unit, its flue and much of the pipework all change at once.
Which boiler type suits your home
The cheapest job is usually the one that keeps your current type. Change type when the house has changed, or when the setup you have cannot keep up.
- Combi: one bathroom, good mains water pressure and no spare room for a cylinder. It is also the quickest type to replace, at a day's work.
- System: two or more bathrooms in use at the same time, with a cylinder in an airing cupboard and no tank in the loft.
- Regular: an older home that already runs a loft tank and a cylinder, especially where mains pressure is low.
- Electric: a flat or small home with no gas supply, or where a flue cannot be routed out.
- Oil or biomass: a rural home off the gas grid that wants to keep a boiler rather than move to a heat pump.
Where the usual pick goes wrong:
- A system boiler and cylinder in a one-bathroom flat, where a combi would free a whole cupboard.
- An electric boiler in a large, draughty house, where electricity prices make every winter expensive.
Converting to a combi: what it adds
Converting a regular or system boiler to a combi costs £3,000 to £5,700 fitted. The extra pays for taking out the loft tank and the hot water cylinder, capping and rerouting the old pipework, and sometimes moving the boiler to a new wall.
A conversion frees the loft and the airing cupboard. Where two showers run at once, though, a system boiler with a cylinder keeps up better, and converting can mean paying more for weaker hot water.
If the boiler is part of a whole-house renovation budget, convert while the floors are up and the walls are open. Rerouting pipe runs before new finishes go down saves making good afterwards.
Boiler prices by brand
The boiler itself is only part of the price. These are unit prices before fitting. Each brand sells an entry, mid and top range, so the spread inside one brand is wider than the gap between brands.
| Brand | Combi | System | Regular |
|---|---|---|---|
| Worcester Bosch | £1,500 – £3,500 | £1,200 – £2,600 | £1,200 – £2,600 |
| Vaillant | £1,500 – £3,700 | £1,200 – £2,200 | £1,200 – £2,200 |
| Viessmann | £1,500 – £3,500 | £2,000 – £2,500 | £2,000 – £2,500 |
| Ideal | £1,300 – £2,500 | £1,300 – £2,500 | £1,300 – £2,500 |
| Baxi | £1,300 – £2,500 | £1,300 – £2,500 | £1,300 – £2,500 |
| Alpha | £1,000 – £2,400 | £1,000 – £2,400 | £1,000 – £2,400 |
Vaillant, Worcester Bosch and Viessmann top out highest for a combi, and Alpha starts lowest. The difference between a unit price here and a fitted price in the first table is the labour, the flue, the parts and the installer's own guarantee.
What a full boiler quote includes
A complete quote covers more than the boiler and a day's labour. The flue, a magnetic filter, a chemical flush of the system, basic controls and any gas pipe upgrade are all part of a standard installation. A quote that leaves them off is not cheaper, it is incomplete, and the missing lines come back once the engineer is on site.
The flush and the filter work as a pair. The flush clears sludge out of the radiators and pipes, and the magnetic filter catches what builds up afterwards, so the new boiler does not start life running on dirty water.
What makes one boiler quote dearer than another
When two quotes for the same house differ, the gap usually traces to one of these:
- Boiler size. A higher output in kW costs more. The right size comes from the home's heating and hot water demand, not from the badge on the old boiler.
- Guarantee length. A longer guarantee raises the price. With a higher-spec model, it is what separates the £1,800 to £3,500 swap band from the £3,000 to £4,500 premium band.
- Brand and model. A top-range unit can cost more than twice an entry model from a different brand, before any labour.
- Moving the boiler. A new location adds hundreds to thousands of pounds, depending on the new gas, water and condensate runs.
- Extra heating. Adding radiators, or wet underfloor heating in an extension, on the same visit adds pipework and can call for a larger boiler.
- Flue route. A vertical flue up through the roof costs more than a horizontal flue straight out through the wall.
- Gas pipe size. An older, narrower gas supply may need upgrading to feed a modern combi.
- Controls. Basic controls come with most combi installs. A smart thermostat or wireless controls are an add-on.
Fixed online price or a local engineer's quote
National online installers quote a fixed price in minutes from a questionnaire, sometimes with photos, and some fit the next working day. A local heating engineer usually visits, surveys and then quotes. That takes longer, but it prices the house as it is.
Either route works when the price matches the job. A fixed price that holds after the survey is a good price. One that grows on the day, because the questionnaire missed a loft tank or a long flue run, is not.
Before you pay a deposit on a fixed online price, ask what happens to it if the survey finds something the questionnaire did not, and get the answer in writing.
Paying monthly for a new boiler
Installers and manufacturers commonly sell boilers on finance. Worcester Bosch offers its £2,475 Greenstar 2000 package at £24.94 a month at 10.9% APR, including VAT and installation.
The monthly figure alone hides the cost. Compare the APR, the term in months and the total amount payable, and ask each installer for the cash price and the finance price side by side. A cheaper boiler on a long term can cost more in the end than a dearer one paid off quickly.
How long a boiler replacement takes
A like-for-like combi swap is one day's work. You are without heating and hot water while the system is drained, fitted and refilled, so if the old boiler still runs, book the replacement outside a cold snap.
| Job | Typical time on site |
|---|---|
| Like-for-like combi swap | 1 day |
| System boiler replacement | 1 – 2 days |
| Regular boiler replacement | 1 – 2 days |
| Back boiler to combi | 2 days |
A standard replacement runs in this order:
- The gas and water are isolated, the system is drained and the old boiler comes off the wall.
- The new boiler and flue go up, with any gas pipe upgrade and a new condensate pipe.
- The radiators and pipework are flushed, and a magnetic filter goes on the return pipe.
- The system is refilled and bled, then the boiler is commissioned and the controls are set.
- The guarantee is registered with the manufacturer and the paperwork is handed over.
Boiler costs by region
The ranges here are UK-wide, and labour is the part that moves with the postcode. A combi swap in London costs more than the same job in the Midlands or a rural area, sometimes a lot more, while the boiler itself carries the same list price everywhere.
So a London quote near the top of the like-for-like band is normal for the capital. The same figure for the same job in Leicester is worth a second quote.
Oil, electric and biomass boiler costs
Homes without mains gas choose between oil, electric and biomass boilers, or a heat pump. These are installed prices for a replacement.
| Boiler | Installed price | Notes |
|---|---|---|
| Electric boiler | £1,700 – £4,500 | No gas supply or flue needed |
| Oil boiler replacement | £4,500 – £5,500 | Common in rural homes off the gas grid |
| Biomass boiler | £10,000 – £18,000 | Burns wood pellets or chips |
An electric boiler can be cheaper to fit because there is no gas work and no flue. It runs at electricity prices, though, so compare running costs before choosing one on the fitted price alone.
Grants for a new boiler in 2026
Most households pay for a new boiler themselves. The main scheme that can fund a replacement boiler in 2026 is ECO4, the Energy Company Obligation. It runs in England, Scotland and Wales and pays for heating and insulation upgrades in low-income and fuel-poor homes.
- Owner-occupiers: the home usually needs an EPC rating of D to G.
- Private tenants: the home needs an EPC rating of E to G, and the landlord has to give permission.
- Income: the household has to be on a low income or in fuel poverty.
Energy suppliers fund ECO4 against targets the government sets them, so the help arrives as work done by a supplier's installer rather than as cash in your account.
ECO4 was due to close on 31 March 2026 and has been extended to 31 December 2026. No supplier scheme follows it. The government is putting £1.5bn of additional grant funding for low-income households into the Warm Homes Plan instead.
The Boiler Upgrade Scheme does not pay for a gas boiler. It pays towards heat pumps and biomass boilers, so it only helps if you are leaving gas or oil behind.
Northern Ireland sits outside ECO4. Its Boiler Replacement Scheme, which paid up to £1,000 towards a new boiler, closed in September 2023.
Repair or replace your boiler
A gas boiler usually lasts 10 to 15 years, and replacement is normally recommended somewhere in that window. Under 10 years, a repair is usually the better spend. Past 15, each repair buys less time.
Replacement moves up the list when:
- The boiler is past 10 years old and the fault is a major part such as the heat exchanger.
- It has broken down more than once in the same heating season.
- The engineer can no longer get parts for the model.
- You are converting to a combi or moving the boiler anyway as part of wider work.
Get the fault diagnosed before pricing a replacement: the engineer's call-out charge buys an answer on whether it is a small part or a major one. A boiler that fires but leaves radiators that won't heat up usually has a fault in the system, such as sludge, air or a stuck valve, and a new boiler on its own will not fix it.
Common questions
How much should a new boiler cost?
Most UK boiler jobs cost £2,500 to £4,000 fitted in 2026. A like-for-like combi swap sits lower, at £1,800 to £3,500. Conversions to a combi run to £5,700 and back boiler replacements to £6,000, because the job moves more than the boiler.
How much does it cost to replace a combi boiler with a new combi?
Replacing a combi with a combi in the same spot costs £1,800 to £3,500 fitted in 2026. A premium model with a longer guarantee costs £3,000 to £4,500. Moving the boiler to another room adds hundreds to thousands of pounds, depending on the pipe and flue runs.
How much does a new system boiler cost?
Replacing a system boiler and keeping the existing cylinder costs £1,800 to £3,500 fitted in 2026, and takes 1 to 2 days. A new cylinder on the same visit is priced on top. The boiler alone runs £1,000 to £2,600, depending on brand and range.
Can I get a new boiler for free?
A funded boiler is possible only through ECO4, and only if your household is on a low income and the home is rated D to G on its EPC. ECO4 runs in England, Scotland and Wales until 31 December 2026. The Boiler Upgrade Scheme does not pay for gas boilers.
Is replacing a boiler a big job?
A like-for-like combi swap is a one-day job, and most system or regular boiler replacements take 1 to 2 days. Removing a back boiler and fitting a combi elsewhere takes around 2 days. You are without heating and hot water while the system is drained and refilled.
How long does a new boiler last?
A new gas boiler usually lasts 10 to 15 years. Replacement is normally recommended within that window rather than after a breakdown, because a winter failure leaves no time to compare quotes. A boiler in that age bracket that needs a major part is usually worth replacing instead.
Is it worth converting to a combi boiler?
Converting pays off in a home with one bathroom and good mains pressure, and less so where two showers run at once. It costs £3,000 to £5,700, against £1,800 to £3,000 for a new regular boiler, and frees the loft tank and the airing cupboard. Moving the boiler at the same time is priced on top.
How much is a Worcester Bosch boiler?
A Worcester Bosch combi costs £1,500 to £3,500 for the boiler alone, and its system and regular boilers cost £1,200 to £2,600. Worcester Bosch lists its Greenstar 2000 30kW combi at an indicative £2,475 fitted, including VAT. The fitted price covers the flue, labour and parts on top of the unit.
Who can fit a new gas boiler?
A gas boiler has to be fitted by an engineer on the Gas Safe Register, and this is a legal requirement rather than a trade preference. Check the engineer's registration on the register before work starts, and ask for the boiler make and model in writing on the quote.
How much does an oil boiler replacement cost?
Replacing an oil boiler costs £4,500 to £5,500 fitted in 2026. Oil heats many rural homes off the gas grid, and the price sits above a gas combi swap. The Boiler Upgrade Scheme does not fund a new oil boiler, only heat pumps and biomass boilers.