How much does a new boiler cost?
Typical UK prices, what changes them, and how we quote.
Which? puts the typical cost of a new boiler, supply and installation included, at anywhere from around £1,400 to £7,000. That is a wide range, and it is wide for good reason: a like-for-like combi swap and a full system change with a new cylinder are very different jobs. Below we explain where your home is likely to sit, what the extras cost, and why we only give a price once we have seen the job.
Typical boiler costs in the UK
The ranges below come from Which? (figures checked in November 2026) and cover the parts of a job that most often change the final bill. They are national figures, not our prices. Rural homes can cost a little more because there are fewer engineers to go round, and London and the South East tend to sit at the top.
Use them as a sense check on any quote you get, including ours.
- New boiler, fully installed: around £1,400 to £7,000 (Which?)
- Converting from a heat-only or system boiler to a combi: an extra £400 to £800 for labour and re-piping (Which?)
- Upgrading the gas supply pipe for a bigger boiler: £100 to £400 (Which?)
- Adding a hot water cylinder when moving away from a combi: £350 to £750 vented, £900 to £1,400 unvented (Which?)
- Power flush on a five-radiator system: £300 to £750 (Which?)
- Smart thermostat: £100 to £250; a standard thermostatic radiator valve about £15 (Which?)
What pushes the price up or down
The boiler is usually the smaller half of the bill once you add labour, flue, controls and system cleaning. These are the things we look at on a survey:
- Boiler type: a combi swap is usually cheapest; system and regular boilers bring cylinders and tanks into it
- Size and brand: bigger outputs and premium models cost more, but oversizing just wastes money
- Moving the boiler: a new position means new gas, water, condensate and flue runs
- Flue route: a short horizontal flue through an outside wall is simple; vertical flues through a roof take longer
- State of the system: old radiators full of sludge need a proper clean before a new boiler goes on
- Controls: building regulations ask for proper controls with a new boiler, and smart options cost more
Like-for-like or a bigger change?
If your current combi is in a sensible place and works with your hot water demand, swapping it for a new combi in the same spot is the cheapest route. Most of the pipework stays.
The price climbs when the job changes shape. Taking out an old back boiler, doing a combi conversion from a tank system, or moving the boiler to another room all add labour and materials. Sometimes they are worth it. Sometimes they are not, and we will tell you which.
How we price your boiler
We do not show a one-size price list because it would be wrong for half the homes that read it. Instead an engineer visits, checks your gas supply, flow rate, flue options and system condition, and then we send a fixed quote in writing.
That quote is the price. If something changes, like you decide to move the boiler after all, we re-quote before doing the extra work. Finance options are also available, subject to status, on our boiler finance page.
Cost by type of boiler
The type of boiler you choose shapes the job more than the badge on the front. As a rule, the closer the new boiler is to your existing boiler, the lower the boiler installation cost, because the pipework, flue and controls mostly stay put.
Which? splits its own price data by gas combi, system and heat-only boiler, plus oil. Here is how each one tends to affect the bill:
- Combi boiler: heats water on demand with no tanks. A like-for-like combi boiler swap is usually the cheapest job going
- System boiler: works with a hot water cylinder but no loft tank, so it suits homes with two busy bathrooms
- Heat-only boiler (also called a regular or conventional boiler): needs a cylinder and a cold water tank in the loft. Converting one to a combi adds around £400 to £800 (Which?)
- Oil boiler: for homes off the gas grid. A straight swap keeps costs down, but a new oil tank adds around £1,300 for a smaller store or £2,400 for a larger one (Which?). See our oil boiler installation page
Labour cost and what a boiler swap involves
Labour is a big part of the total cost, and it is the part that moves most from one house to the next. On a straight boiler swap, the engineer drains the system, takes the old boiler off the wall, fits the new one to the same pipes and flue position, then cleans and commissions everything.
Moving the boiler to a new location is a different job. Shifting it from the kitchen to the loft, say, means new gas, water and condensate runs and a new flue, so relocating the boiler always adds labour. Which? also notes that many engineers quote one total figure rather than an itemised bill, which is fair enough as long as the quote names the boiler, controls and flue work.
When is replacing a boiler worth it?
There is no rule that says a boiler has to go at a certain age. If your old boiler is safe, reliable and serviced every year, keeping it running can be the sensible choice.
The case for boiler replacement gets stronger when repairs start stacking up, parts become hard to find, or the boiler is an older non-condensing model. Every new gas boiler fitted today is a condensing boiler, which recovers heat from the flue gases that older designs sent straight outside. Our guide on how long a boiler lasts covers the warning signs.
What happens, step by step
Request a quote
Fill in our quote form and tell us roughly what you have now.
Survey
We visit, measure up and talk through what you want from your heating and hot water.
Fixed price
You get one written figure for the whole job, with the boiler model and controls listed.
What is included
- Free home survey by a Gas Safe registered engineer
- Written fixed quote covering boiler, labour, flue, controls and system clean
- Clear options if a different boiler type would suit you better
- Manufacturer-approved installer warranty options explained
- No pressure to book, and the quote is free
New boiler cost FAQs
How much is a new combi boiler?
Which? gives a typical installed range of around £1,400 to £7,000 for a new boiler. A straight combi-for-combi swap usually sits towards the lower end. Moving it, converting from a tank system or upgrading the gas pipe pushes it higher. We confirm a fixed figure after a survey.
Why do boiler quotes vary so much?
Because the jobs are different, even when the boiler is the same. Flue length, pipe sizes, the state of the radiators and the controls all change the labour. Ask every installer to list the boiler model, controls and flue work so you are comparing like with like.
Is the cheapest boiler the best value?
Not often. A cheap boiler on a dirty system with no filter can be calling for repairs in a few years. The better test is total cost over the boiler's life, including servicing and warranty terms.
Do you charge for the survey?
No. The survey and quote are free, and there is no obligation to go ahead.
Can I get a grant for a new gas boiler?
Grants for gas boilers are limited and depend on your circumstances. The government's main scheme, the Boiler Upgrade Scheme, is for heat pumps rather than gas boilers. See our Boiler Upgrade Scheme page if you are weighing up a heat pump.
How long does boiler replacement take?
A like-for-like combi swap is normally a one-day job. Converting a heat-only system to a combi, or moving the boiler to a new location, can stretch to two or three days because of the extra pipework. Your fixed quote tells you how long we expect to be there.
Does a 20 year old boiler need replacing?
Not automatically. Age on its own is not a fault, but a boiler that old is more likely to need parts that are getting scarce, and it may be a less efficient design. If it keeps breaking down or struggles at its service, replacing it usually beats paying for another repair. We will give you an honest view after a look.
What is the average cost of a new boiler?
A single average is not much use because jobs vary so much. Which? gives a range of around £1,400 to £7,000 installed, and where you land depends on the type of boiler, the labour involved and any extras like a new cylinder. A straight combi swap tends to sit near the lower end.
Get a fixed price for your home
Tell us about the job and we will arrange a free survey.