How much does a new boiler cost in the UK? (2026)

A new boiler in the UK in 2026 costs £1,500–£4,000 installed for a combi (the most common type), confirmed across MyJobQuote, Heatable, Checkatrade, and HomeOwners Alliance. The average is around £2,400–£3,000. System and conventional boilers run roughly the same range, with system boilers slightly higher at the top end because they are usually paired with a hot water cylinder.

How to read this guide#

Two kinds of figures appear below:

• Headline price ranges (boiler types, swap labour, service, heat pump installations, the Boiler Upgrade Scheme grant): cross-referenced against multiple UK cost-guide publishers, with the BUS grant figure taken directly from GOV.UK.
• Practical guidance (when to swap like-for-like vs convert, what is included in a typical quote, red flags specific to boiler quotes, warranty implications): drawn from standard UK installation practice.

Where a figure could not be verified across multiple sources, we have either flagged the single source or omitted the figure.

Headline ranges (verified)#

Boiler installation cost by type#

The averages for any boiler type cluster around £2,400–£3,000 installed. A budget combi swap by an online installer can come in lower; £1,500 is achievable for a like-for-like swap with a budget-tier boiler (e.g. Worcester Bosch 2000 or Ideal Logic basic). A premium combi (Viessmann 200-W, Vaillant ecoTEC Plus 935) with smart controls and ancillaries sits at £3,500–£4,500.

Boiler swap labour only#

Labour-only cost for a like-for-like swap, where the customer supplies the boiler:

• £600–£1,700 (MyJobQuote, typical £1,000)

Excludes the boiler itself, flue extension, ancillaries, and chemical clean.

Annual service#

• £85–£180 for a routine annual service by a Gas Safe registered engineer (£100 is typical; MyJobQuote).

Air-source heat pump#

• £8,000–£14,000 gross for a typical 5–8 kW system in a 3-bed home (HomeOwners Alliance: £12,500 average installed).
• Boiler Upgrade Scheme grant: £7,500 applied directly when the installer is MCS-certified and the property is eligible (GOV.UK, statutory).
• Net to the homeowner: approximately £500–£6,500.

Larger systems (12–16 kW for 4-bed or poorly insulated properties) cost £12,000–£18,000 gross before grant. Quotes that omit a hot water cylinder upgrade, hydraulic separator, or radiator-upgrade allowance are usually missing scope.

Common ancillaries#

Practical guidance (industry standard)#

What a typical boiler installation quote covers#

A complete combi-boiler installation should include:

• The boiler unit itself
• Standard horizontal flue, with one flue extension if needed
• Fitting labour by a Gas Safe engineer
• System flush (chemical) before commissioning
• Pressure test and commissioning
• Removing and disposing of the old boiler
• Manufacturer warranty registration
• Building Control notification (CP12 / Gas Safe notification; most installers handle this)

It often does not cover:

• Magnetic filter retrofit if your system does not already have one (manufacturer warranties increasingly require one)
• Smart thermostat if you want one
• Gas pipe upgrade if the existing run is undersized for a higher-output boiler, common when upgrading from a 25 kW to a 35 kW combi
• Condensate pump if there is no suitable drain near the boiler position
• Vertical flue parts for boilers in basement, ground-floor positions with no external wall access (£300–£600 extra)
• Power flush if the existing system is heavily contaminated (a chemical flush is included; a power flush is a different scope)

When you compare boiler quotes, the easy mistake is comparing a £2,800 quote inclusive of magnetic filter, smart thermostat, and chemical flush against a £2,200 quote that excludes them. Read the inclusions list line by line.

Like-for-like swap vs conversion#

A like-for-like swap (combi to combi, same wall position, same output bracket) is the cheapest path. The installer can usually quote firm in advance and complete in a day. £1,500–£2,500 is typical.

A conversion is a different proposition:

• Regular boiler to combi: removes the hot water cylinder and feed-and-expansion tank, frees up the airing cupboard. Adds £800–£1,200 over a swap (Heatable). Total typically £2,500–£4,000.
• Back-boiler removal to combi: more invasive, includes capping the old gas supply, removing the boiler from the fireplace, and fitting the combi elsewhere. Adds roughly £400 over a regular-to- combi conversion. Total typically £3,500–£5,000 (Heatable).
• Combi to heat pump: largest scope change. Includes a hot water cylinder (heat pumps cannot deliver instant DHW like a combi), often larger radiators, and indoor/outdoor unit installation. Without the BUS grant, this is significantly more expensive than a boiler. With the £7,500 grant, net cost lands close to a premium boiler.

If the existing boiler position cannot be re-used, expect £750+ for relocation labour on top of the install (MyJobQuote: £750 typical relocation cost).

When to consider a heat pump instead#

A heat pump is worth considering if any of the following apply:

• Your existing boiler is at end of life (10+ years) and needs replacing anyway
• You have decent loft and wall insulation, or are willing to fund retrofits at the same time
• Your radiators are reasonably sized (heat pumps run lower flow temperatures and benefit from larger radiators)
• You can afford the upfront cost net of the £7,500 BUS grant

It is less suitable when:

• Your home is poorly insulated and you are not in a position to retrofit
• Your radiators are small and would need wholesale replacement
• You have hot-water-on-demand expectations from a combi (heat pumps use a cylinder, not on-demand DHW)
• You are off-gas already on oil; different economics, check oil-vs- heat-pump separately

The UK government's plan is to phase out new gas boiler installations in the long term. Heat pumps now have a viable grant-supported economic case for many properties, but it is not universal.

Red flags in boiler quotes specifically#

Beyond the standard quote red flags (covered separately), some are boiler-specific:

No Gas Safe engineer number on the quote. Gas Safe registration is a legal requirement to install or service gas boilers. The engineer's ID number is on a card and on the public register. Verify it at gassaferegister.co.uk before signing.

No mention of the Building Control notification. All gas boiler installations must be notified to Building Control under the Competent Person Scheme. The installer does this through their Gas Safe registration. A quote that does not mention notification is either including it (most do) or skipping it (illegal). Ask.

"Cash discount" of 20%. Boiler installs are commonly the target of cash-job offers. The discount is the VAT and the income tax combined. Refusing the cash discount is the right call (see our VAT-registered builder guide).

Unrealistically short install time. A proper combi swap takes 4–6 hours including the chemical flush, pressure test, and commissioning. A 2-hour install is skipping at least one of those, usually the system flush, which voids most manufacturer warranties.

No magnetic filter mentioned. Worcester Bosch, Vaillant, Ideal, and most other major manufacturers now require a magnetic filter for warranty validity. A quote that does not include one is either assuming you already have one or planning to skip it. Ask.

Oversized boiler. A 35 kW combi in a 2-bed flat is wasted output and worse efficiency than a correctly-sized 25 kW unit. If the quoted boiler kW seems large for your property, ask why. Honest installers size to the heat-loss calculation, not to the largest unit they have in stock.

Scrapping the old boiler without a heat-loss recalculation. When you change boiler type or output, the new unit should be sized to a fresh heat-loss calculation. Plumbers who quote a "same as before but new" without measuring are skipping a step that affects efficiency and running cost for the next decade.

Lifetime cost beyond the install price#

The cheapest boiler at install is rarely the cheapest over a 10–12 year lifetime. The variables that matter:

• Manufacturer warranty length. 7–10 years (Worcester Bosch, Vaillant, Viessmann premium) is genuinely meaningful. Cheaper boilers often have 2–5 year warranties. A break-down in year 4 of an out-of-warranty boiler is £400–£800 in repair costs.
• Energy efficiency. Modern condensing combis run at 90–94% efficiency. The difference between a 90% and 94% boiler is roughly £50–£100/year in gas costs.
• Annual servicing. Required by most warranties; £85–£180/year. Skipping it to save the cost is a false economy if it voids a £4,000-boiler warranty.

Over 10 years, a £3,200 premium boiler with a 10-year warranty often costs less than a £2,000 budget boiler with a 5-year warranty plus two out-of-warranty repairs.

Comparing your boiler quote#

The quote checker on this site analyses each line against current UK rates, flags missing scope (magnetic filter, system flush, smart controls, Building Control notification), and runs a Companies House check on the installing company. For a £3,000 install, the £14 cost is a small fraction of the decision; the information returned is what turns "this quote looks roughly fair" into "every line is accounted for."