Typical prices in 2026
The cheapest boiler replacement is a like-for-like swap: an old combi out, a new combi in, in the same place, using the same flue route. That's usually £2,000–£3,500 fitted. Changing boiler type, moving the boiler or upgrading the hot water system all push the price up.
These figures include the boiler, labour, a new flue, a system clean and filter, basic controls, and registering the installation with Gas Safe and the manufacturer.
| Job | Typical cost | Usual time |
|---|---|---|
| Combi to combi, same position | £2,000 – £3,500 | 1 day |
| System boiler replacement | £2,500 – £4,200 | 1 – 2 days |
| Regular (heat-only) boiler replacement | £2,400 – £4,000 | 1 – 2 days |
| Conventional system converted to combi | £3,200 – £5,500 | 2 – 3 days |
| Boiler moved to a new location | +£500 – £1,500 | Extra day |
| Premium brand / longer warranty | +£300 – £1,000 | – |
Indicative costs to replace a gas boiler (2026, supplied and fitted)
What makes up the price
Many people are surprised that the boiler itself is often less than half the total. A mid-range combi might cost the installer £900–£1,600. The rest is labour, parts and the work needed to bring the system up to current standards.
- The boiler – brand, output and warranty length all matter
- Labour – usually one or two engineers for a day or more
- Flue – a new flue is normally needed, and extensions add cost
- System clean – a chemical flush or power flush to protect the new boiler
- Magnetic filter – required by most manufacturers for the warranty
- Controls – a programmable or smart thermostat
- Condensate pipe – may need rerouting or insulating
- Gas pipe upgrade – older 15mm supplies sometimes need upsizing
- Removal of the old boiler and Building Regulations notification
Why quotes vary so much
Two quotes for the same house can differ by £1,000 or more. Sometimes that's because one installer is recommending a bigger boiler, a longer warranty or a power flush. Sometimes it's because one quote leaves things out. And sometimes it's simply demand – in winter, when boilers break down, installers are busier.
Make sure each quote names the boiler model, its output in kW, the warranty length, and what's included. Our guide to comparing heating quotes explains how to line them up properly.
Need a heating engineer?
Describe the job and compare free quotes from local heating engineers near you.
Free and no obligation. Quote requests are handled by our partner, Bark.
Combi, system or regular?
If you already have a combi, replacing it with another combi is usually the cheapest option. If you have a hot water cylinder, you'll need to decide whether to keep it (system or regular boiler) or switch to a combi. Combis suit most flats and smaller houses with one bathroom; homes with two or more bathrooms often do better with a system boiler and cylinder.
See combi vs system vs regular boilers and replacing a conventional boiler with a combi.
Warranties and finance
Most new boilers come with a manufacturer's warranty of 5–12 years when fitted by an accredited installer and registered. Longer warranties usually depend on an annual service. Our guide to boiler warranties explains the small print.
Many installers offer finance, which can spread the cost. Check the interest rate and the total amount payable before signing.
Is it time to replace?
A boiler doesn't have to be replaced just because it's old. But if it's over 12–15 years old, breaking down regularly, or parts are getting hard to find, replacement is often better value than repeated repairs. See signs you need a new boiler and how long gas boilers last.
You can check typical boiler costs and get free quotes from Gas Safe registered boiler installers.
