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Introduction
If your boiler is on its last legs, the first question is usually the simplest one: how much is a new one going to cost? The honest answer is that most straightforward swaps in 2026 cost somewhere between about £1,800 and £3,500 fitted, but the final figure depends far more on the job than on the boiler itself.
This guide breaks down what you can expect to pay for each type of installation, what the online fixed-price companies charge, which extras push the price up, and what a fair quote should include. I have written it from the installer’s side of the job, so you know what to ask before anyone picks up a spanner.
The short version
- Like-for-like combi swap: typically £1,800 to £3,500 fitted. Heatable’s median combi quote in early 2026 was £2,300.
- Converting to a combi or moving the boiler: expect £3,000 to £5,700, because of the extra pipework and removing tanks or a cylinder.
- Online fixed prices: start from around £1,500 to £1,750 for a budget combi, and £2,100 to £2,900 for Worcester Bosch, Vaillant or Viessmann.
- No grant for gas boilers: the £7,500 Boiler Upgrade Scheme only covers heat pumps and biomass, and gas boilers carry 20% VAT.
- Get the extras in writing: a flush, a magnetic filter and the right controls should be in the price, not added on the day.
How much does a new boiler cost?
Here are typical fitted prices (supply and installation, including VAT) from three UK cost guides updated in 2026. They don’t agree exactly, which is normal: prices vary by region, by brand and by how much work your home needs.
| Type of job | Heatable | Boiler Central | Checkatrade |
|---|---|---|---|
| Combi, like-for-like | £1,800 to £3,500 (premium £3,000 to £4,500) | £1,800 to £4,000 (average £2,295) | £2,500 to £4,000 (average £3,000) |
| System boiler | £1,800 to £3,500 | £2,500 to £5,000 (including a new cylinder) | Not given as a fitted price |
| Regular (heat-only) boiler | £1,800 to £3,000 | £2,200 to £5,500 (including tanks) | Not given as a fitted price |
| Regular or system to combi | £3,000 to £5,700 | Around £2,699 (system to combi) | Around £4,000 |
| Back boiler to combi | £3,500 to £6,000 | £3,000 to £5,000 | Around £4,000 |
| Moving the boiler | Not given | Not given | £600 to £1,000 extra |
Prices are guides, not quotes. Your own price depends on the boiler, the access, the flue route and the state of your existing system.
In my experience, the boiler itself is rarely what makes a quote expensive. It’s the workaround: moving the boiler to a new room, upgrading an undersized gas pipe, a long or vertical flue, or ripping out a hot water cylinder and loft tanks to go combi. If two quotes for the same boiler are a long way apart, that’s usually where the differences are.
What the online installers charge
Fixed-price online installers have made boiler prices much easier to compare. You answer a few questions, pick a boiler and get a price, often with installation as soon as the next day. These are the headline prices on each company’s website, checked on 5 October 2026.
| Installer | Cheapest advertised | Examples | Warranty | Finance |
|---|---|---|---|---|
| iHeat | £1,745 (Navien NCB 300) | Alpha Etec NX £2,145; Worcester Greenstar 2000 £2,245; Worcester Greenstar 4000 £2,445 | 5 to 10 years depending on the boiler | 0% APR with no deposit |
| Boxt | From £1,745 | Brand-dependent | Up to 12 years manufacturer, plus 1 year workmanship | 0% on selected boilers; 9.9% APR example |
| Heatable | From £1,995 (Glow-worm) | Worcester from £2,095; Vaillant from £2,795; Viessmann from £2,895 | 10 years parts and labour on Worcester, Vaillant and Viessmann, plus 12 months workmanship | 0% over 2 to 4 years by brand; 9.9% APR over 3 to 10 years |
| British Gas | No headline price | Quote after survey | 5 years parts and labour, with annual servicing | 0% over 3 years or up to 10 years at 9.9% APR |
| WarmZilla | From £1,489 (Vokera) | Ideal Logic £1,549; Worcester 2000 £1,699 | Up to 12 years | Available |
Always check what’s included: some prices cover a flush, filter and controls, and some add them on.
A low headline price is only a good deal if it includes what your home actually needs. Online quotes are based on what you tell them, so if the installer turns up and finds the gas pipe needs upgrading or the flue can’t go where you’d hoped, the price can change on the day. Take photos of your boiler, flue and gas meter when you fill in the form, and answer the questions carefully.
Extras that change the price
These are the most common additions I see on boiler quotes, with typical costs from 2026 guides. Some online installers include several of them as standard.
| Extra | Typical cost | When you need it |
|---|---|---|
| Powerflush | £300 to £800 | Older systems with sludge, cold spots or a noisy boiler. A cheaper chemical flush is often enough on cleaner systems. |
| Magnetic system filter | £100 to £200 fitted | On every new installation; most manufacturers require one for the full warranty. |
| Gas pipe upgrade (15mm to 22mm) | £250 to £400 | When the existing pipe is too small to feed a modern combi. |
| Vertical flue | About £300 to £600 | When the flue goes through the roof rather than an outside wall. |
| Flue extension or plume kit | £75 to £300 | When the flue terminal is close to a window, door or boundary. |
| Heating controls | £100 to £300 | Needed to meet the rules (see below) if your current controls don’t comply. |
| Thermostatic radiator valves | £40 to £60 each | Needed on most radiators when a boiler is replaced. |
| Removing a cylinder | £100 to £170 | When converting to a combi. |
| Removing loft tanks | About £350 | When converting from a regular boiler to a combi. |
What a fair quote should include
Whoever you use, a proper boiler quote should spell out the following. If it’s vague on any of them, ask before you agree to anything.
- A Gas Safe registered engineer. It’s a legal requirement for any gas work. You can check an engineer’s ID card number on the Gas Safe Register.
- The exact boiler model and output, not just “a Worcester.” A 25 kW and a 30 kW combi suit different homes.
- A system flush and a magnetic filter. Fitting a new boiler to a dirty system shortens its life and can void the warranty.
- Compliant controls. In England, a new combi needs a timer, a room thermostat, and one extra efficiency measure, and most radiators need TRVs
- The flue route and condensate pipe. Where they’ll run, and whether any extension or plume kit is included.
- Removal and disposal of the old boiler, plus any tanks or cylinder if you’re converting.
- Building regulations notification and warranty registration. The installer should notify Gas Safe of the work and register the warranty with the manufacturer for you.
Rules that affect your installation
- Boiler Plus (England): Every new gas boiler must be at least 92% efficient and come with a timer and room thermostat. A new combi also needs one of the following: weather compensation, load compensation, flue gas heat recovery, or a smart thermostat with automation and optimisation.
- Room-by-room control: since June 2022, building regulations in England require TRVs (or similar) on radiators when a boiler is replaced, except in the room with the main thermostat.
- New-build homes: the Future Homes Standard, published in March 2026 and in force from March 2027, means new homes won’t be built with gas boilers.
- Existing homes: there’s no ban on replacing a gas boiler in your current home. The government’s Warm Homes Plan says no one will be forced to rip out a working boiler.
- “Hydrogen-ready” boilers: the government hasn’t decided whether hydrogen will be used for home heating, so treat this as a nice-to-have, not a reason to pay more.
You can read more about which controls are worth having in my guide to smart thermostats and controls.
Grants and VAT
This is where boilers and heat pumps differ most. The Boiler Upgrade Scheme grant of £7,500 only applies to heat pumps and biomass boilers, not gas boilers. ECO4, which is winding down in 2026, rarely pays for a boiler on its own, and its replacement, the Warm Homes Plan, is focused on low-carbon heating and insulation.
VAT works differently too. A gas boiler is charged at the standard 20% rate for most households, while heat pumps currently carry 0% VAT. That’s one reason the gap between the two after the grant is smaller than many people expect.
Is it time to replace your boiler?
Worcester Bosch and Baxi both put a boiler’s typical lifespan at 10 to 15 years with an annual service. If yours is older than that, breaking down more often, or needs a part that’s no longer made, it’s worth getting prices before it fails in the middle of winter, when you have no time to compare.
Replacing an old, inefficient boiler can also cut your gas bill. The Centre for Sustainable Energy, quoting Energy Saving Trust figures, estimates that replacing a G-rated boiler with an A-rated one in a semi-detached home saves around £320 a year at July 2026 prices. Newer boilers that are simply a few years old won’t save anywhere near that much.
Ready for a price?
Get a fixed-price boiler quote online
iHeat fits Worcester Bosch, Vaillant, Viessmann and Ideal boilers across the UK, with installation as soon as the next day and 0% finance on selected models. The online quote takes about 60 seconds.
Get my iHeat quoteInstaller’s tip: get a quote from a local Gas Safe engineer too, so you can compare. If you go ahead through this link, I may earn a small commission, at no extra cost to you.
Boiler or heat pump?
If you’re replacing a boiler anyway, it’s worth a quick look at the alternative. A typical combi swap costs around £2,300, while Octopus Energy says its typical heat pump installation costs £4,459 after the £7,500 grant. A heat pump costs more up front and needs the right home, but it can cost less to run and won’t be affected by future changes to gas. My gas boilers vs heat pumps guide sets out the numbers, and my heat pump installer comparison shows who fits them.
Frequently asked questions
How much does a new combi boiler cost in 2026?
Most like-for-like combi swaps cost £1,800 to £3,500 fitted, including VAT. Budget models from online installers start from around £1,500, while premium brands and more complex jobs can go above £4,000.
How long does it take to fit a new boiler?
A straightforward swap usually takes a day. Converting to a combi or moving the boiler can take one to two days, or longer if tanks and pipework need to come out.
Can I get a grant for a new gas boiler?
Usually not. The Boiler Upgrade Scheme only covers heat pumps and biomass. Some low-income households have had boilers funded through ECO4, but it rarely covers a boiler on its own and is winding down in 2026.
Do I need a powerflush with a new boiler?
Not always. Your system should be cleaned before a new boiler goes on, but a cheaper chemical flush is often enough. A powerflush makes sense on older systems with sludge, cold spots or a history of problems.
Is a longer warranty worth paying for?
It can be, but read the conditions. Most warranties need the boiler registered within 30 days, a magnetic filter fitted and a service every year by a Gas Safe engineer. Miss a service and the warranty may not pay out.
Final thoughts
A new boiler is one of the bigger bills most homeowners face, but it doesn’t have to be a stressful one. Most straightforward swaps land between about £1,800 and £3,500, and the online fixed-price companies have made it much easier to see what’s fair. What matters most is that the quote covers the right boiler size, a clean system, compliant controls and a properly registered warranty.
Get at least two prices, check exactly what’s included, and if your boiler is still working, use that time to compare properly. If you’re also wondering whether it’s the right moment to switch to a heat pump, my guide to upgrading your gas boiler is a good next step.