UK 2026 cost guide / Updated June 2026
Boiler replacement cost UK 2026: £1,800 to £5,000 by type, with four options to weigh.
Most UK households facing a failing boiler treat the question as "how much for a new one?". The honest answer is that the cheapest path depends on which of four routes makes sense for your home. This guide builds the decision tree first, then prices each branch with calibrated UK 2026 ranges.
Independent. Not affiliated with any boiler manufacturer, installer, or finance provider. For a published reference point, the Energy Saving Trust puts the average cost of replacing a G-rated gas boiler with an A-rated one, with thermostatic radiator valves, at £3,500 in Great Britain. Other cited sources: BOXT's published fixed installed prices, manufacturers' warranty terms, gov.uk and Ofgem grant pages, Gas Safe Register requirements, and Boiler Plus 2018.
Your four options, side-by-side
Every working boiler eventually arrives at this fork. Costs for each path are UK 2026 ranges including supply, labour, certification, and removal. Click a branch to see the depth page.
Repair
£100-£900
Single-fault fix on the existing boiler. PCB swap, pump replacement, diverter valve, or heat exchanger.
Best when
Boiler under 10 years old, first major fault, repair cost under 50% of a swap.
More on this option →Like-for-like swap
£1,800-£4,500
Same fuel, same boiler type. The cheapest replacement path. 1-day install on most homes.
Best when
Boiler over 12 years old, breakdowns getting frequent, no need to change fuel or layout.
More on this option →Convert (e.g. back boiler to combi)
£2,500-£5,000
New pipework + flue + decommission existing setup. Back boiler conversion, regular-to-combi, system-to-combi.
Best when
Awkward layout in current system, wanting to free up loft tank space, modernising heating.
More on this option →Heat pump alternative
£8,000-£14,000
Air source heat pump (after £7,500 BUS grant typically £500-£6,500 net). No gas at all.
Best when
Well-insulated home, EPC C+ ideally, room for an outdoor unit, and an MCS certified installer.
More on this option →The repair branch is cost-justified up to about 50% of a like-for-like swap. The convert branch trades £500 to £2,000 of extra pipework for a cleaner layout. The heat-pump branch trades a higher upfront cost for the £7,500 BUS grant and matches the direction of the Future Homes Standard, which requires low-carbon heating in new homes in England from March 2027.
Quick answer: the three most-asked replacement scenarios
Combi-to-combi swap
£1,800 - £3,500
Cheapest UK replacement path. 1-day install. Lowest published fixed price we found: BOXT, from £1,699 (Ideal Logic Combi 24kW, October 2026).
System swap
£2,000 - £4,000
For 3+ bedroom homes with a hot water cylinder. 1-2 day install. No loft tank needed if upgrading from regular to system.
Back-boiler conversion
£2,500 - £5,000
Most complex. Remove unit behind gas fire, reroute pipework, cut new flue. 2-3 day install. Almost always converted to a wall-mounted combi.
Cost by boiler type
All-in prices include supply of the new boiler, labour, removal of the old unit, flue, controls, and Building Control notification under Part L.
| Type | Typical cost | Install time | Best for | Deep dive |
|---|---|---|---|---|
| Combi | £1,800 - £3,500 | 1 day | 1-3 bed homes, one bathroom | Combi cost |
| System | £2,000 - £4,000 | 1-2 days | 3+ bed, 2+ bathrooms, hot water cylinder | System cost |
| Regular (heat-only) | £2,000 - £4,500 | 1-2 days | Older homes with loft tank, large like-for-like | Regular cost |
| Back boiler conversion | £2,500 - £5,000 | 2-3 days | 1960s-1980s houses with back boiler behind gas fire | Back boiler cost |
What is included in a typical UK replacement quote
A reputable Gas Safe registered installer should itemise every line. If the quote is a single all-in figure with no breakdown, ask for one. Six line items should appear on every replacement quote:
Boiler unit
Named modelAsk for the make, model and output by name, and the warranty term the installer will register. Manufacturers do not publish consumer prices; compare like-for-like quotes instead.
Installation labour
£500 - £1,5001-2 days for a like-for-like swap. Multi-day installs scale linearly. London labour adds about 20% to this band.
Flue + fittings
£100 - £300Standard horizontal flue is cheapest. Vertical flue through the roof or longer runs (over 2m) cost more. Flue must meet Part J distance rules from windows and doors.
Magnetic system filter
£80 - £150 fittedTraps debris before it damages the heat exchanger. Now required by most manufacturers to validate extended warranties.
Powerflush or chemical flush
£300 - £600Strongly recommended on systems over 10 years old. Some installers include it, others charge separately; check before signing.
Building Control notification
Included £100 - £200Gas Safe installers self-certify under the Competent Persons Scheme. The certificate should be in the quote.
Cost by house size
Larger homes need higher-output boilers, more radiators, and longer install times. These are all-in like-for-like replacement ranges. Switching boiler type or relocating the boiler adds £300-£1,000 of pipework cost on top.
| Property | Recommended kW | Best type | Typical cost |
|---|---|---|---|
| 1-bed flat | 24 kW | Combi | £1,800 - £2,500 |
| 2-bed terrace | 24-28 kW | Combi | £1,900 - £2,800 |
| 3-bed semi | 28-30 kW | Combi | £2,000 - £3,000 |
| 4-bed detached | 30-35 kW | Combi or system | £2,500 - £4,000 |
| 5+ bed large home | 35+ kW | System + cylinder | £3,000 - £5,500 |
Brand quick compare
Installed prices are BOXT's published fixed "from" prices, checked 22 October 2026. Warranty terms are from each manufacturer's own UK warranty pages. Baxi and Viessmann have no published installed price.
Worcester Bosch
Installed from £2,199
Warranty: Up to 12 years on the Greenstar 8000 Life when fitted by a Worcester Bosch Accredited Installer
UK (Worcester), part of the Bosch group
Vaillant
Installed from £2,519
Warranty: Up to 10 years on ecoTEC plus, ecoTEC exclusive and ecoFIT pure (up to 45 kW) with the Advance Boiler Protection Kit, registered through Advance
Germany (Remscheid), Vaillant Group
Ideal
Installed from £1,699
Warranty: Up to 12 years on Vogue Max combi and system; 10 years on Logic Max combi, system and heat
UK (Hull)
Baxi
No published installed price
Warranty: 10 years on the 800 Combi 2 and 800 System 2; 7 years on the 600 Combi 2 and 600 System 2
UK, part of BDR Thermea Group
Viessmann
No published installed price
Warranty: 2 years standard, 7 years free on registration; Vitodens 100-W and 200-W can be extended to 10 or 12 years for a fee
Germany (Allendorf)
Grants and finance: who pays less
Two government schemes can reduce or eliminate the upfront cost. Plus 0% finance via approved installers is the standard spread-cost route.
ECO4 scheme
Free boiler possibleFunded by energy suppliers under an Ofgem-administered obligation that runs until 31 December 2026. For households on qualifying benefits whose home is EPC D to G (E to G if privately rented). A broken efficient boiler is replaced only if it cannot be economically repaired, and suppliers may ask for a contribution.
Read full ECO4 eligibility guide →Boiler Upgrade Scheme
£7,500 grantHeat pumps only, not gas boilers. £7,500 for air source or ground source heat pumps, £2,500 for air-to-air, £5,000 for biomass boilers in rural off-gas properties. Applied for by the MCS certified installer, not the homeowner. England and Wales only.
Read full BUS guide →Not eligible for grants? See 0% finance options for spreading the cost.
How to use this site
If you're not sure your boiler needs replacing at all, start with 8 signs you need a new boiler then read repair or replace. If you know you're replacing, jump straight to cost by type or cost by brand. If you're considering a heat pump, start with gas boiler vs heat pump cost.
Named prices on this site come from BOXT's published fixed installed prices and the Energy Saving Trust; grant terms from gov.uk and Ofgem. The wider cost bands are editorial ranges, not a published survey; treat them as a guide and compare written quotes. See methodology for the full source ledger.
Frequently asked questions
How much does it cost to replace a boiler in the UK in 2026?
The all-in cost of a like-for-like boiler replacement in the UK in 2026 typically sits between £1,800 and £4,500 including supply, labour, removal, flue, and Gas Safe certification. A combi-to-combi swap is the cheapest path (£1,800 to £3,500). Switching boiler type, converting from a back boiler, or moving the boiler location adds £500 to £2,000 of pipework and decommissioning cost.
Is it cheaper to repair or replace an old boiler?
Cost-justified up to about 50% of a replacement. A single fault repair on a modern boiler costs £100 to £900. If your boiler is under 10 years old and this is its first major fault, repair is almost always the right call. Over 12 years old with two or more callouts in the last year, replacement starts winning on whole-cost terms.
What grants are available for boiler replacement in 2026?
ECO4 (an obligation on energy suppliers, administered by Ofgem, running until 31 December 2026) for households on qualifying benefits in an EPC D-G home (E-G if privately rented); a working-but-broken efficient boiler is only replaced if it cannot be economically repaired. The Boiler Upgrade Scheme gives £7,500 towards a heat pump, not a gas boiler. Local councils may also offer means-tested grants.
Should I switch to a heat pump instead of replacing my gas boiler?
Worth modelling, but rarely the right answer unless the property is already insulated to EPC C or better. An air source heat pump costs £8,000 to £14,000 installed (typically £500 to £6,500 net of the BUS grant). Running costs are comparable to a high-efficiency gas combi in a well-insulated home, higher in a poorly insulated one.
How long does a boiler replacement take?
Like-for-like combi swap: 6-8 hours, done in a day. Boiler type change: 1.5-2 days. Back-boiler conversion: 2-3 days.
Do I need a Gas Safe registered engineer?
Yes. By law all gas boiler installations in the UK must be carried out by a Gas Safe registered engineer under the Gas Safety (Installation and Use) Regulations 1998. Verify the engineer's ID at gassaferegister.co.uk.
Related independent guides
Last verified June 2026. See methodology for the full source ledger and refresh cadence. 2026-05-12