What a new boiler costs
A like-for-like gas combi or system boiler swap typically costs £1,800 to £3,500 installed, in quotes the online installer Heatable gave across 2,000 jobs from January to June 2026, with a median of £2,300 for a standard combi. DESNZ puts the average new gas boiler at about £3,500 including VAT. Our new boiler cost guide covers what a quote should include and the extras.
| Job | Typical installed cost |
|---|---|
| Combi, like-for-like swap | £1,800 to £3,500 |
| System, like-for-like swap | £1,800 to £3,500 |
| Regular (heat-only), like-for-like swap | £1,800 to £3,000 |
| Regular or system converted to a combi | £3,000 to £5,700 |
| Oil boiler replacement | £4,500 to £5,500 |
The data behind this table
Heatable's typical installed prices, updated 25 September 2026: one firm's quotes, so a local installer may quote more or less. We found no published price for moving a boiler, a power flush or an LPG boiler that we could check, so the calculator leaves them out and says so.
What replacing an old boiler saves
The Energy Saving Trust puts the saving from replacing an old gas boiler with an A-rated condensing boiler and new controls at about £190 to £350 a year in a semi-detached house, depending on the old boiler's rating, at July 2026 fuel prices.
| Home | Old boiler rated D | Old boiler rated E | Old boiler rated F | Old boiler rated G |
|---|---|---|---|---|
| Detached house | £220 | £270 | £350 | £500 |
| Semi-detached house | £190 | £210 | £240 | £350 |
| Mid-terrace house | £140 | £160 | £180 | £270 |
| Detached bungalow | £170 | £190 | £220 | £320 |
| Flat, mid floor | £90 | £100 | £120 | £170 |
The data behind this table
Energy Saving Trust, for a gas home fitting an A-rated condensing boiler with a programmer, room thermostat and thermostatic radiator valves in place of an older boiler with a programmer and room thermostat. D is 78 to 82% efficient, E 74 to 78%, F 70 to 74% and G under 70%. The Trust gives no end-terrace figure, so the calculator uses the semi-detached one, and none for oil or LPG.
Measured savings are smaller. Across homes that had a new condensing boiler fitted, gas use fell by a median 2.3%, whatever the boiler replaced, which is the figure the calculator uses for an older condensing boiler. Our guide to whether it is worth replacing an old boiler explains the gap.
How the calculator works
Cost is Heatable's typical range for the job: a like-for-like swap of the boiler type you choose, a conversion to a combi, or an oil boiler. Saving is the Energy Saving Trust's figure for your type of home and the old boiler's rating, or the range from D to G if you are not sure; for an older condensing boiler it is the DESNZ measured median applied to the gas an average home like yours uses at the price cap of 7.97p per kWh. Payback is the cost range divided by the saving. The heat pump figure is the median installed price under the Boiler Upgrade Scheme for the size of heat pump the home needs, less the grant.
We leave out what we cannot source: the cost of moving a boiler, conversions to a system or regular boiler, LPG boiler prices, and any saving for oil or LPG, or for replacing a boiler under 10 years old.
Frequently asked questions
How much does a new boiler cost?
A like-for-like gas combi or system boiler swap typically costs £1,800 to £3,500 installed, and converting a regular or system boiler to a combi £3,000 to £5,700. DESNZ puts the average new gas boiler at about £3,500 including VAT.
How much will a new boiler save?
Replacing an old gas boiler with an A-rated one and new controls saves about £190 to £350 a year in a semi-detached house, according to the Energy Saving Trust, and up to £500 in a detached house. Replacing a boiler that is already condensing saves far less: a measured median of 2.3% of gas use.
Why is there no saving for oil or LPG?
The Energy Saving Trust publishes its yearly boiler savings for gas homes only, and we found no other current source we could check, so we leave it out rather than guess.
Does the cost include moving the boiler?
No. Moving a boiler adds pipework and often a new flue, and we found no published price for it that we could check. Ask for it to be priced after a survey.
Should I get a heat pump instead?
A heat pump for a 3 bed semi costs about £5,200 after the £7,500 grant, against about £3,500 for a gas boiler. Our boiler vs heat pump calculator compares the two over 15 years.
Data sources
- Heatable, New boiler installation costs 2026 (updated 25 September 2026): typical installed prices from 2,000 of its own quotes, January to June 2026. Heatable is an online boiler installer, so these are one firm's prices. Checked 5 October 2026.
- Energy Saving Trust, Boiler types explained (last updated 20 May 2026): yearly savings for a gas heated home fitting an A-rated condensing boiler with a programmer, room thermostat and thermostatic radiator valves in place of an older boiler, by the old boiler's rating, at July 2026 fuel prices; £3,500 typical cost of replacing a G-rated gas boiler. Checked 5 October 2026.
- Department for Energy Security and Net Zero, Boiler Upgrade Scheme 2026 to 2030 summary business case, footnote 8: a new gas boiler costs about £3,500 including VAT. Other home sizes are scaled from it by our model, which is our assumption.
- Department for Energy Security and Net Zero, NEED impact of measures data tables 2026: the median fall in gas use in homes that had a new condensing boiler fitted, with and without new heating controls, priced at the Ofgem cap gas rate of 7.97p per kWh.
- GOV.UK, Apply for the Boiler Upgrade Scheme: grants for air source and ground source heat pumps, biomass boilers and air-to-air heat pumps, checked 5 October 2026.
- Heat pump cost from our heat model, js/heat-model.js: the median installed price under the Boiler Upgrade Scheme for a heat pump of the size the home needs (DESNZ statistics, August 2026). EPC points from our EPC calculator model.