New Boiler Installation: Costs, Rules and Fixed Quotes

A new boiler installation means a Gas Safe registered installer taking out your old boiler, fitting a new one, cleaning the heating system and registering the work. For a like-for-like gas combi swap, most UK households pay £1,800 to £3,500 fitted in 2026, and Heatable puts the median quote at £2,300. Changing the type of boiler or moving it adds to the cost and the time.

Tell us your postcode and what you have now, and we’ll pass your request to Gas Safe registered installers who cover your area. Each one surveys your home and gives you their own fixed quote, so you can compare them side by side.

Combi, system or regular: which do you need?

The right boiler depends on how many people use hot water at once and what’s already in the house.

Type	How it heats water	Best for
Combi	On demand from the mains; no tank or cylinder	Flats and homes with one bathroom and good mains pressure
System	Heats a cylinder; parts such as the pump are built in	Two or more bathrooms used at once, or a heat pump or solar later
Regular (heat-only)	Heats a cylinder fed by tanks in the loft	Older systems where you want to keep the existing pipework

A combi is sized for hot water flow, not house size, so a bigger kW figure doesn’t mean a warmer home. If your mains pressure is weak, a combi may disappoint at the shower. Ask the installer to measure the flow rate before you decide.

Swapping a regular boiler for a combi frees up the loft and airing cupboard but costs more: Heatable puts the full conversion at £3,000 to £5,700. If you think you may want a heat pump in a few years, keeping the cylinder can make that switch simpler.

How a boiler installation works

Survey. The installer looks at your current boiler, flue route, gas pipe, water pressure and radiators, in person or by video. A fixed quote without one is a guess.
Quote. You get a written price listing the boiler model and output, the flue, controls, filter, system clean and warranty.
Fitting day. The old boiler comes off, the system is drained and cleaned, and the new boiler, filter and controls go in. A like-for-like combi swap usually takes about a day; a conversion takes about two.
Commissioning. The installer tests gas pressure and combustion, fills in the manufacturer’s commissioning checklist and shows you how to use the controls.
Paperwork. The installer notifies building control and registers the warranty. You get a building regulations compliance certificate in the post.

Rules your installer must follow

Gas Safe registration

Only a Gas Safe registered engineer can legally fit a gas boiler. Check the ID card before work starts; the back lists the work they are qualified to do. You can also look up the business on the Gas Safe Register website.

Building Regulations

Fitting a new boiler is notifiable building work. GOV.UK explains that a registered installer can self-certify it, so you don’t need to apply to building control yourself. Keep the certificate, as you may need it when you sell.

Boiler Plus (England)

Since April 2018, the Boiler Plus standards have applied to new gas boilers in England. The government factsheet sets out three points:

the boiler must be at least 92% efficient (ErP)
a timer and room thermostat must be fitted with every gas and oil system
a combi must come with one extra energy-saving measure: flue gas heat recovery, weather compensation, load compensation, or smart controls with automation and optimisation

Smart controls are one way to meet it. See smart thermostat installation for what they involve.

Oil boilers

Oil boilers need an OFTEC registered installer. Heatable puts a replacement at £4,500 to £5,500. See oil boiler servicing and our heating oil prices guide.

Gas boiler or heat pump?

Gas boilers aren’t being banned. In January 2025 the government dropped the plan to stop sales of new gas boilers from 2035, so a new gas boiler is still a legal choice for an existing home.

There’s no Boiler Upgrade Scheme grant for a gas boiler. In England and Wales, the scheme pays £7,500 towards an air source or ground source heat pump instead, according to GOV.UK. If your boiler is being replaced anyway, it’s worth pricing both. Our heat pump cost guide, Boiler Upgrade Scheme guide and heat pump installation page cover the numbers.

How to compare boiler quotes

Quotes for the same job can be far apart. Selectra says installers can differ by £1,000 to £1,500. To compare fairly:

Get at least three quotes for the same boiler output and warranty length, or close equivalents.
Line up what’s included: removal of the old boiler, a system clean, a magnetic filter, the flue kit, controls, condensate pipe and any gas pipe upgrade.
Ask about the warranty. Most depend on a yearly service, so add that cost over the warranty period.
Question a power flush listed as standard. A chemical clean is often enough; a power flush is for systems with heavy sludge.
Question a bigger boiler than you have now, with no reason given.
Don’t sign on the day because a discount is about to expire.

Our new boiler cost guide checks a quote line by line and explains when a price over £4,000 is fair.

When to replace your boiler

Plan a replacement rather than waiting for a winter breakdown if:

a repair quote includes a heat exchanger or control board on an older boiler
parts for your model are getting hard to find
it has broken down more than once this year
you’re renovating and want the boiler moved

If your boiler has just stopped, start with boiler repair; many faults are a single part. Once your new boiler is in, book a yearly boiler service to keep the warranty valid.

Typical new boiler prices, fitted

Job	Typical UK price	Notes
Like-for-like combi swap	£1,800 to £3,500	About a day; Heatable median £2,300 in the first half of 2026
Premium-brand combi swap	£3,000 to £4,500	Longer warranties are common
System or regular boiler replacement	£1,800 to £3,500	1 to 2 days, keeping the existing cylinder
Regular or system to combi conversion	£3,000 to £5,700	Tanks and cylinder removed, pipework changed
Back boiler to combi	£3,500 to £6,000	About 2 days
Moving the boiler or changing type	+£500 to £1,200	New flue, pipework and gas run
Larger gas supply pipe	+£100 to £400	If the existing pipe is too small for the new boiler
Power flush, if needed	+£300 to £750	Only for a badly sludged system
Oil boiler replacement	£4,500 to £5,500	OFTEC registered installer

Sources: Heatable and Selectra new boiler cost guides (2026) and Which? boiler prices guide. Expect the top of each range in London and the South East.

Boiler installation guides

How much does a new boiler cost?

Boiler installation by city

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Scotland

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Northern Ireland

Belfast

Common questions

How much does a new boiler cost to install?

A like-for-like combi swap usually costs £1,800 to £3,500 fitted in 2026, with a median of about £2,300 according to Heatable. Changing from a regular or system boiler to a combi costs more, about £3,000 to £5,700.

How long does it take to fit a new boiler?

A straight combi swap normally takes about a day. Replacing a system or regular boiler takes one to two days, and a conversion to a combi or the removal of a back boiler usually takes about two.

Are gas boilers being banned?

No. In January 2025 the government dropped the plan to ban new gas boiler sales from 2035. You can still have a gas boiler fitted in an existing home, and you can keep using the one you have.

Can I get a grant for a new gas boiler?

Not through the Boiler Upgrade Scheme, which only funds heat pumps and biomass boilers in England and Wales. Some households on certain benefits may get help through other schemes; see our heating grants page.

Do I need building regulations approval for a new boiler?

Yes, but a Gas Safe registered installer can self-certify the work and notify building control for you. You should get a building regulations compliance certificate afterwards. Keep it for when you sell.

Should I get a combi or a system boiler?

A combi suits most homes with one bathroom and good mains water pressure. A system boiler with a cylinder suits homes with two or more bathrooms in use at once, or if you might add a heat pump or solar later.

New boiler installation