Cost to Replace a Gas Boiler With a Heat Pump
The short answer
- £3,500 to £8,000 for a heat pump after the £7,500 grant, against about £3,500 for a new gas boiler, in a typical 3-bed semi
- About £1,465 less over 15 years for a heat pump on a heat pump tariff; on a standard tariff the boiler wins by about £2,600
- £211 a year saved against gas on a heat pump tariff, so the extra upfront cost takes about 8 years to recover
Replacing a gas boiler with a heat pump costs £3,500 to £8,000 out of pocket for a typical 3-bed semi once the £7,500 Boiler Upgrade Scheme grant is deducted, against about £3,500 for another gas boiler. Over 15 years, a heat pump on a heat pump tariff costs about £1,465 less than a new boiler using the typical cost of each; on a standard electricity tariff, the boiler wins by about £2,600. The decision comes down to your electricity tariff, the grant and how long you plan to stay in your home. This guide runs the full numbers: upfront cost, running costs, servicing and the total over 15 years.
The 15-year comparison at a glance
The tariff decides it. On a heat pump tariff the heat pump wins for a 3-bed semi by about £1,465 over 15 years; on a standard tariff the boiler is cheaper.
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| Cost element (3-bed semi) | New gas boiler | Heat pump (standard tariff) | Heat pump (HP tariff) |
|---|---|---|---|
| Upfront cost | About £3,500 | £3,500 to £8,000 (after the grant) | £3,500 to £8,000 (after the grant) |
| Annual heating cost | £877 | £937 | £666 |
| Annual servicing | £100 | £100 | £100 |
| 15-year running and servicing | £14,655 | £15,555 | £11,490 |
| 15-year total cost | £18,155 | £19,055 to £23,555 | £14,990 to £19,490 |
The data behind this table
Gas boiler at 90% efficiency and 7.97p/kWh. Heat pump at the measured median efficiency of 2.78, on a standard tariff at 26.32p/kWh or a heat pump tariff such as Cosy Octopus, about 18.7p per kWh with most heating in the cheap hours. Servicing £100 a year for either system, as in our calculator. The boiler is the DESNZ average of about £3,500 including VAT. 9,900 kWh annual heat demand, Ofgem price cap for October to December 2026. The heat pump cost is the middle half of what installers reported for a heat pump of this size under the Boiler Upgrade Scheme, covering the system, labour and VAT as they recorded it; if your home needs radiator or other work that is not in the installer's price, add it. Standing charges are left out: cap the gas supply after switching and you also stop paying the £108 a year gas standing charge.
Use our boiler vs heat pump calculator for a personalised comparison based on your property type and energy costs.
The tariff is the tipping point
On a standard electricity tariff, the boiler is cheaper over 15 years. On a heat pump tariff, the heat pump wins for this 3-bed semi at typical costs, by about £1,465, and for a 4-bed detached house by about £800. This single decision swings the comparison by about £4,100 over 15 years.
What it costs to replace a gas boiler with a heat pump
£11,000 to £15,500 installed for a 3-bed semi, or £3,500 to £8,000 after the £7,500 grant. A new gas boiler is about £3,500, so the typical gap after the grant is about £1,700.
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New gas boiler
DESNZ puts the average cost of a new gas boiler at about £3,500 including VAT, in its Boiler Upgrade Scheme business case. Our calculator uses that figure for a 3-bed home, installed, and scales it by size: about £2,950 for 1 bed, £3,200 for 2 bed, £3,800 for 4 bed and £4,050 for 5 bed. The Boiler Upgrade Scheme does not pay towards gas boilers.
Air source heat pump
An air source heat pump for a 3-bed semi costs £11,000 to £15,500 installed, with a median of £12,700. That is the middle half of what installers reported for a heat pump of about 9 kW under the Boiler Upgrade Scheme in 2025/26. The £7,500 grant, available in England and Wales, brings it to £3,500 to £8,000 out of pocket. Ask for any radiator changes and the hot water cylinder to be itemised in the quote, so you can see what the price includes.
After the grant, the upfront gap between a boiler and a heat pump is about £1,700 using the typical figure for each (£5,200 against £3,500). Smaller homes need smaller heat pumps, which cost less, so the gap narrows.
See our cost by house type guide for exact figures for your property.
Running cost comparison
On a heat pump tariff a 3-bed semi saves £211 a year against gas. On a standard tariff the heat pump costs more to run: £937 against £877 for the gas boiler.
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This is where the long-term economics play out. Here are the annual heating costs by property type for each system.
| Property type | Gas boiler | HP (standard) | HP (HP tariff) | Annual saving (HP tariff vs gas) |
|---|---|---|---|---|
| 2-bed terrace | £558 | £596 | £424 | £134 |
| 3-bed semi | £877 | £937 | £666 | £211 |
| 3-bed detached | £932 | £997 | £708 | £224 |
| 4-bed detached | £1,164 | £1,244 | £884 | £280 |
The data behind this table
Based on the Ofgem price cap for October to December 2026. Gas 7.97p/kWh at 90% efficiency. Heat pump at the measured median efficiency of 2.78. Standard tariff 26.32p/kWh. Heat pump tariff 18.7p/kWh, Cosy Octopus with most heating in the cheap hours. Average insulation. The terrace row is a mid-terrace.
On a heat pump tariff, a 3-bed semi saves £211 a year against gas. Over 15 years that is about £3,165 in running costs alone. A 4-bed detached saves £280 a year, about £4,200 over 15 years. Read our heat pump running costs guide for the full breakdown.
Maintenance and reliability
Both need servicing, and our calculator allows £100 a year for either. Lifespan and repair costs vary too much to put numbers on, so ask each installer about the warranty and servicing schedule.
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Both systems need servicing. Our calculator allows £100 a year for either. Use a Gas Safe registered engineer for a gas boiler and, for a heat pump, ideally the MCS certified installer who fitted it, following the manufacturer's servicing schedule. MCS guidance for installers notes that a poorly maintained heat pump can become noisier over time.
Lifespan and repairs. How long each system lasts and what it costs to repair vary widely with the model and how well it is looked after, so we have not put numbers on them. Ask each installer what warranty comes with the system and what the servicing schedule is.
When the boiler wins
If you will not switch to a heat pump tariff, need major preparation or will sell within a few years. On the standard rate a heat pump costs about 7% more to run than gas.
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A new gas boiler is the better financial choice if:
You will not switch to a heat pump tariff. On the standard rate of 26.32p/kWh, a typical heat pump costs about 7% more to run than gas. If you cannot or will not switch tariff, there is no running cost saving to offset the higher upfront cost.
Your property needs major preparation. If your home requires extensive radiator upgrades, pipework changes, and a new hot water cylinder on top of the heat pump cost, the total investment may not pay back within your expected time in the property.
You are selling within a few years. At the typical costs above, the extra upfront cost of a heat pump takes about 8 years to recover on a heat pump tariff. If you are moving sooner, you may not recoup it.
When the heat pump wins
On a heat pump tariff, off the gas grid, or when your boiler has failed. Running costs on a heat pump tariff are about 24% lower than gas, and the extra upfront cost pays back in about 8 years.
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A heat pump is the better financial choice if:
You switch to a heat pump tariff. This is the single biggest factor. On a heat pump tariff, running costs are about 24% lower than gas from day one in a home with average insulation. Read our tariff comparison.
You plan to stay 8 years or more. At the typical costs above, that is when a heat pump on a heat pump tariff has paid back its extra upfront cost. The cheaper your quote, the sooner it comes.
You are on oil or LPG. If you are off the gas grid, a heat pump is cheaper to run even on a standard tariff. In our model, with heating oil at 11.3p per kWh (the BoilerJuice UK average of 116.20p a litre on 25 September 2026; oil prices move) and LPG at 9.5p, oil and LPG homes from a 2-bed terrace to a 4-bed detached house save about £110 to £500 a year on a standard tariff and £280 to £860 on a heat pump tariff, and the grant rises to £9,000 until March 2027 if the home has no mains gas connection.
You want to stop burning fossil fuel at home. A heat pump burns nothing on site, and adding solar panels cuts the electricity it buys from the grid.
Your boiler has already failed. If you are facing a boiler replacement anyway, the incremental cost of choosing a heat pump (after the BUS grant) is much smaller than the total cost. This is the optimal time to switch.
The hybrid option
A smaller heat pump paired with a gas boiler, but with no grant. Hybrid heat pumps ran at a median 2.50, below the 2.78 of standalone air source heat pumps, and you service two systems.
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If you are not ready to commit fully, a hybrid system pairs a smaller heat pump with a gas boiler. The heat pump covers milder weather and the boiler takes over in the coldest spells. In the Electrification of Heat trial, heat pumps in hybrid systems ran at a median 2.50 over a year, below the 2.78 of standalone air source heat pumps.
The Boiler Upgrade Scheme does not fund hybrid systems, so you pay the full cost, and you keep two systems to service. A hybrid can suit homes where a full heat pump installation would be disruptive, but check the numbers against a full heat pump with the grant.
What to do if your boiler is still working
Insulate now and fit the heat pump when the boiler needs replacing. Measured gas savings were 3.2% for loft and 12.0% for cavity wall insulation, and a home needing less heat can use a smaller heat pump.
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If your boiler is working well, the cheapest approach is often to insulate now and plan the heat pump for when the boiler needs replacing.
Start with loft insulation and cavity wall insulation. In homes that had them fitted in 2023 to 2024, the median measured gas saving was 3.2% for loft insulation and 12.0% for cavity wall insulation (DESNZ NEED), and a home that needs less heat can use a smaller heat pump when the time comes. Check if ECO4 covers free insulation for you before it closes on 31 December 2026.
Use our EPC improvement planner to prioritise upgrades and our heat pump calculator to see what a future switch would cost.
Frequently asked questions
Is a heat pump cheaper than a new gas boiler over 15 years?
On a heat pump tariff, yes at typical costs, though not by much. For a 3-bed semi, the 15-year total is about £16,690 for a heat pump after the £7,500 grant against £18,155 for a new gas boiler, about £1,465 less. On a standard tariff, the boiler is about £2,600 cheaper over 15 years. Use our calculator for your property.
Should I replace my boiler with a heat pump?
If your boiler has failed, a heat pump is worth serious consideration, especially with the £7,500 Boiler Upgrade Scheme grant in England and Wales. If it is still working well, insulate first and switch when it needs replacing. Loft and wall insulation cut the heat your home needs whichever system you choose.
How much more does a heat pump cost upfront than a boiler?
DESNZ puts the average new gas boiler at about £3,500 installed, including VAT. A heat pump for a 3-bed semi costs £11,000 to £15,500, or £3,500 to £8,000 after the £7,500 grant. Using the typical figure for each, the gap after the grant is about £1,700. See our costs by house type.
Will gas boilers be banned in the UK?
Not in existing homes: there is no ban on replacing a gas boiler. In England, the Future Homes Standard comes into force on 24 March 2027, with transitional arrangements, and new homes built to it will have low carbon heating.
What are the maintenance costs for heat pumps vs boilers?
Both need regular servicing, and our calculator allows £100 a year for either system. Follow the manufacturer's servicing schedule; for a heat pump it also helps keep the unit quiet.
Data sources
Heat pump costs come from DESNZ Boiler Upgrade Scheme statistics, and efficiency from the Electrification of Heat trial. Energy prices come from the Ofgem price cap, the boiler cost from DESNZ and oil prices from BoilerJuice.
Show every source
Heat pump installed costs from DESNZ Boiler Upgrade Scheme statistics, August 2026 (Tables A1.3A and Q1.1A). Heat pump efficiency from the Electrification of Heat trial (Energy Systems Catapult for DESNZ, December 2024), Tables 1.2 and 1.3. Energy prices from the Ofgem price cap, October to December 2026. Gas boiler cost from the DESNZ Boiler Upgrade Scheme 2026 to 2030 summary business case, footnote 8. Heating oil price from BoilerJuice, 25 September 2026. Grant rules, including the exclusion of hybrid systems, from GOV.UK. Measured insulation savings from NEED Impact of Measures 2026. Future Homes Standard dates from MHCLG Building Circular 01/2026. Servicing guidance from the MCS installation guidance on heat pump noise.