TL;DR — Boiler Replacement Cost At A Glance
- A new combi boiler, supplied and fitted, typically costs £1,800 – £3,000 inc VAT; a system boiler runs £2,500 – £5,000, with complex jobs reaching £6,000.
- London and the South East add roughly 10–20% to these figures.
- The final price depends on the boiler type and model, the complexity of the install, and any upgrades such as a system flush or new pipework.
- Only a Gas Safe registered engineer may install a gas boiler — and the installation must be notified to Building Control.
- Most homeowners replace a boiler every 10–15 years; an ageing boiler with a costly fault is usually cheaper to replace than repair.
- A new A-rated boiler can cut heating bills and often comes with a 5–12 year manufacturer's warranty.
Get a fixed-price quote for a new boiler from a Gas Safe registered engineer — check prices and book online or call to talk through the right boiler for your home.
How Much Does Boiler Replacement Cost In 2026?
Replacing a boiler in the UK costs £1,800 – £3,000 inc VAT for a combi boiler and £2,500 – £5,000 for a system boiler, supplied and fitted. More involved projects — moving the boiler to a new location, converting from one boiler type to another, or high-output premium models — can reach £6,000 or more. In London and the South East, add around 10–20% to reflect higher labour rates.
Those figures cover the boiler unit, the engineer's labour, standard fittings and controls, and the paperwork that comes with a compliant install. The price you pay depends most on the type of boiler you need and how much extra work the job involves — a straightforward like-for-like swap is far cheaper than relocating the boiler and re-running pipes.
Here is what a new boiler typically costs across the UK in 2026:
| Job type | Rest of UK | London & South East |
|---|---|---|
| Combi boiler (like-for-like swap) | £1,800 – £3,000 | £2,000 – £3,600 |
| System boiler (supplied & fitted) | £2,500 – £5,000 | £2,800 – £6,000 |
| Heat-only / conventional boiler | £2,300 – £4,500 | £2,600 – £5,400 |
| Complex install (relocation or conversion) | up to £6,000 | up to £6,500+ |
Figures include VAT and reflect 2026 market rates. The exact price depends on the boiler and your home — get a fixed quote here.
Boiler Replacement Cost By Boiler Type
The type of boiler you choose is the biggest single factor in the total. Combi boilers are compact and the most common in UK homes; system and heat-only boilers suit larger properties with higher hot-water demand and often work well with a cylinder.
| Boiler type | Best suited to | Supplied & fitted (rest of UK) | Supplied & fitted (London) |
|---|---|---|---|
| Combi boiler | Flats and small-to-medium homes with one bathroom | £1,800 – £3,000 | £2,000 – £3,600 |
| System boiler | Homes with two or more bathrooms and a hot-water cylinder | £2,500 – £5,000 | £2,800 – £6,000 |
| Heat-only (conventional/regular) boiler | Older homes with a tank in the loft and a cylinder | £2,300 – £4,500 | £2,600 – £5,400 |
| Oil boiler | Homes off the mains gas grid | £3,000 – £6,000 | £3,300 – £6,500+ |
| Electric boiler | Small homes/flats with no gas supply | £1,800 – £4,000 | £2,000 – £4,500 |
Switching from one type to another — for example, moving from a heat-only system to a combi and removing the cylinder and loft tanks — adds labour and pushes the price towards the top of the range.
What Affects The Cost Of A New Boiler?
Several factors decide the final figure.
1. The Boiler Type And Model
The unit itself is a big chunk of the cost. A budget combi and a premium high-output model can differ by well over £1,000 before labour. Higher outputs, better efficiency and longer warranties all push the price up.
2. Like-For-Like Swap Or A More Complex Job
Replacing a boiler in the same spot with the same type is the cheapest scenario. Moving the boiler, converting between boiler types, or upgrading pipework and controls all add labour and materials.
3. Your Location
London and the South East sit around 10–20% above the rest of the UK on labour, which is the main regional difference on installation-heavy jobs.
4. System Cleaning And Extras
Fitting a new boiler onto an old, sludgy system risks damaging it, so a power flush or chemical clean is often recommended (and sometimes required to keep the warranty valid). A magnetic filter, new thermostat or smart controls are common add-ons.
5. Flue, Condensate And Gas Supply Work
Extra flue length, a new condensate route, or an upgraded gas pipe to feed a higher-output boiler all add cost. These are common when relocating the boiler.
6. Warranty And Compliance
A longer manufacturer warranty can raise the upfront price but protects against future repair bills. The installation must also be notified to Building Control and registered, which a reputable installer handles for you.
What's Included — And What's Not
Usually included in a boiler replacement:
- The new boiler unit
- Removal and safe disposal of the old boiler
- Labour, standard fittings and connections
- A basic set of controls (programmer/thermostat)
- Commissioning, safety checks and Building Control notification
Often charged separately:
- A power flush or system clean
- A magnetic system filter
- Smart controls or a smart thermostat upgrade
- New or upgraded radiators and pipework
- Extra flue components or relocating the boiler
Ask for an itemised quote so you can see exactly what is included before work begins.
Can You Do It Yourself?
No. Installing or replacing a gas boiler is notifiable work that must be done by a Gas Safe registered engineer — it is illegal for an unregistered person to fit a gas boiler in the UK, and the consequences of getting it wrong include gas leaks, carbon monoxide and fire. Oil boilers require an OFTEC registered installer.
There is genuinely no safe DIY route here. What you can do is prepare: clear access to the boiler, decide on the boiler type and any upgrades in advance, and keep your paperwork so the warranty stays valid. Everything from the gas connection to commissioning and Building Control notification is a job for a qualified professional.
How To Save Money On Boiler Replacement
- Get 2–3 quotes and compare like-for-like — check the boiler model, warranty length and what's included, not just the headline price.
- Choose the right boiler for your home, not the biggest — an oversized boiler costs more to buy and run.
- Book in spring or summer when engineers are less stretched than the autumn/winter rush.
- Bundle upgrades sensibly — doing a power flush and new controls during the install is cheaper than separate visits later.
- Look into finance and manufacturer offers, which can spread the cost or add years of warranty.
- Keep the new boiler serviced annually to protect the warranty and avoid early repair bills.
How To Hire A Good Heating Engineer
For a gas boiler, the installer must be on the Gas Safe Register — ask to see the ID card and check the number on the official register. For oil, look for OFTEC registration. Confirm the installer is insured, provides a written, itemised quote, handles Building Control notification, and registers the manufacturer's warranty on your behalf. Reviews and references are worth checking on a purchase this size.
With Fantastic Services, you get Gas Safe registered engineers, clear fixed pricing and help choosing the right boiler for your property — book online and get a compliant, warranty-backed installation.
Frequently Asked Questions
How Much Does It Cost To Replace A Boiler In 2026?
A new combi boiler costs £1,800 – £3,000 inc VAT supplied and fitted, and a system boiler £2,500 – £5,000, with complex installs reaching around £6,000. London and the South East add roughly 10–20%.
How Much Does The Boiler Unit Itself Cost?
The boiler on its own usually accounts for a large share of the total, with the rest going on labour, fittings and extras. Budget models are cheaper, while high-output and premium boilers with long warranties cost more, which is why supplied-and-fitted prices vary so widely.
How Long Does A Boiler Replacement Take?
A straightforward like-for-like combi swap is often done in a day. Converting between boiler types, relocating the unit, or adding a cylinder and system upgrades can take two to three days.
How Often Should A Boiler Be Replaced?
Most boilers last 10–15 years. Frequent breakdowns, rising bills, an unavailable parts supply, or a failed heat exchanger are all signs that replacement is the better-value option. See the boiler repair cost guide to weigh up repair versus replace.
Does A New Boiler Need To Be Installed By A Gas Safe Engineer?
Yes. Fitting a gas boiler is notifiable work that legally must be carried out by a Gas Safe registered engineer, who also notifies Building Control. Oil boilers require an OFTEC registered installer.
Will A New Boiler Save Money On Energy Bills?
Often, yes. Replacing an old, inefficient boiler with a modern A-rated condensing model can reduce gas use, especially when paired with good controls such as a smart thermostat. The saving depends on the age of the old boiler and how the home is heated.
Do You Need A Power Flush When Replacing A Boiler?
Frequently. Fitting a new boiler onto a system full of sludge can damage it and may invalidate the warranty, so a power flush or chemical clean is commonly recommended. A magnetic filter then helps keep the system clean afterwards. See the power flush cost guide for typical prices.
