Heat Pump vs Gas Boiler: The Real Numbers

With energy prices changing every quarter and climate concerns mounting, many UK homeowners are weighing the switch from gas boilers to heat pumps. But what does this transition really cost, and when does it make financial sense? This comparison breaks down installation costs, running costs and the wider picture, using Energy Saving Trust, government and price cap figures, to help you make an informed decision.

Installation Costs: The Initial Investment

The upfront cost difference between heat pumps and gas boilers is significant and often the primary consideration for homeowners.

Gas Boiler Installation Costs

Checkatrade's new boiler cost guide (March 2026) puts the average cost of a gas boiler, supplied and installed, at around £3,000. A like-for-like combi boiler replacement usually costs £2,500 to £4,000.

Gas Boiler Costs by Job (Checkatrade guide, March 2026)

Like-for-like combi replacement: £2,500 - £4,000
New system boiler: around £3,000
New conventional (regular) boiler: around £3,000
Replacing a system or conventional boiler with a combi: around £4,000 on average

For a gas combi, Checkatrade splits the price into the boiler itself (£650 to £3,000) and installation (£1,000 to £2,000). Moving the boiler or changing the type of system adds to the cost. These are guide prices, not quotes.

Heat Pump Installation Costs

Air source heat pump (ASHP) installations cost considerably more. The Energy Saving Trust says the typical cost of installing an air source heat pump is around £12,000, before any grant.

What People Paid Under the Boiler Upgrade Scheme (April–June 2026)

Median installed price: £12,908
Lower quartile: £11,128
Upper quartile: £15,627
Median heat pump size: 8 kW

Air-to-water heat pumps in England and Wales, including the grant value. Source: DESNZ Boiler Upgrade Scheme statistics, July 2026.

Heat pump installations include the outdoor unit, a hot water cylinder, heating controls, radiator upgrades (if needed), and sometimes underfloor heating. Properties with poor insulation may need additional preparatory work, increasing costs.

The Boiler Upgrade Scheme: Closing the Cost Gap

The government's Boiler Upgrade Scheme (BUS) in England and Wales takes £7,500 off the cost of an air source heat pump, which narrows the gap considerably. With this grant:

A typical £12,000 air source heat pump installation would come down to about £4,500
Ground source heat pumps also get £7,500, biomass boilers £5,000 and air-to-air heat pumps £2,500 (since 28 April 2026)
Eligible off-gas-grid homes heated by oil or LPG can get £9,000 towards an air source or ground source heat pump until 31 March 2027
Your installer must take the grant off the upfront price

There is no income test. You need to own the property and be replacing fossil fuel heating such as oil, gas, electric or LPG. You no longer need a valid Energy Performance Certificate, but most new builds, social housing and hybrid heat pumps are not eligible, and the installer must be MCS certified. Good insulation still helps a heat pump run efficiently.

Running Costs: The Annual Expense Battle

While installation costs favour gas boilers, running costs are much closer. The comparison depends on your home's insulation, your tariff and the gap between gas and electricity prices.

Energy Prices from 1 October 2026

Under the Ofgem price cap for 1 October to 31 December 2026 (announced 26 August 2026), typical Direct Debit rates are:

Gas: 7.97p per kWh (standing charge: 29.68p per day, including 5% VAT)
Electricity: 26.32p per kWh (standing charge: 54.83p per day; VAT removed from 1 October 2026 to 31 March 2027)

Electricity costs more than three times as much as gas per unit, which has historically made electric heating expensive. A heat pump's efficiency changes this equation.

Efficiency: The Game Changer

A gas boiler generates heat by burning gas, and even a modern condensing boiler cannot turn all of the energy in the gas into heat. Heat pumps don't generate heat directly; they move it from the outside air into your home.

The Energy Saving Trust says that for every unit of electricity a heat pump uses, it produces three units of heat. Which? says a heat pump's Seasonal Coefficient of Performance (SCOP) in the UK is generally around 3.0, or 300% efficient. That is what lets electric heating compete with gas.

Annual Running Cost Comparison

The Energy Saving Trust has estimated how annual bills change when a gas boiler in a three-bedroom semi-detached home is replaced with a standard air source heat pump, with radiator upgrades as needed:

Heat pump set-up	Replacing an old, inefficient gas boiler	Replacing an efficient gas boiler
Standard electricity tariff	Saves around £220 a year	Costs around £110 a year more
Standard tariff, gas account closed	Saves around £330 a year	Saves around £4 a year
Heat pump tariff, gas account closed	Saves around £530 a year	Saves around £204 a year

Typical costs, last reviewed September 2026. Source: Energy Saving Trust, fuel prices as of July 2026. Estimates, not a guarantee for your home.

Against an efficient gas boiler on a standard tariff, the gas boiler is slightly cheaper to run. Several factors can swing the comparison in favour of heat pumps:

Better insulation: Well-insulated homes require less heat, reducing absolute costs and allowing heat pumps to operate more efficiently
Heat pump tariffs: In EST's figures, a heat pump tariff plus closing your gas account turns an extra cost of around £110 a year into a saving of around £204
Smart controls: Weather compensation and good controls help a heat pump run at its most efficient
Energy prices: The price cap changes every quarter, and the gap between electricity and gas prices decides how running costs compare

Where Heat Pumps Save the Most

EST's estimates show the biggest savings when a heat pump replaces heating that costs more to run than mains gas (least and most efficient old system):

Replacing electric storage heaters: around £1,200 or £800 a year on a standard tariff
Replacing an LPG boiler: around £780 or £290 a year on a standard tariff
Replacing an oil boiler on a heat pump tariff: around £460 or £110 a year
Replacing an old gas boiler on a heat pump tariff, gas account closed: around £530 a year

These are estimates for a typical three-bedroom semi-detached home, not a guarantee.

Maintenance and Servicing

Gas Boiler Maintenance

Annual service: Recommended to keep the boiler safe and efficient, and often a condition of the warranty
Who can work on it: Only an engineer on the Gas Safe Register
Lifespan: Depends on the model, water quality and how well it is maintained
Older boilers: Ask whether parts are still available before paying for a big repair

Heat Pump Maintenance

Annual service: Recommended; check what the warranty requires
Who can work on it: An engineer trained on heat pumps; work on the refrigerant circuit needs F-Gas certification
No combustion: No flue and no burning of fuel in your home
Warranties: Lengths vary by manufacturer and installer, so compare them when you get quotes

Total Cost of Ownership

A lifetime comparison depends on future energy prices, repair costs and how long each system lasts in your home, none of which can be predicted reliably. Rather than rely on a single 20-year figure, compare these for your own home:

The installed price of each option, after any grant
Running costs on the tariff you will actually use
Whether you can close your gas account and stop paying the gas standing charge
Servicing costs and warranty terms
How long you plan to stay in the property

Beyond the Numbers: Other Considerations

Carbon Emissions

Heat pumps produce far lower carbon emissions than gas boilers for the same amount of heat. Because a heat pump makes about three units of heat from each unit of electricity, each unit of heat carries much less carbon than heat from burning gas.

Gas: 0.213 kg CO2e per kWh (Energy Saving Trust carbon factor)
Electricity: 0.225 kg CO2e per kWh (Energy Saving Trust carbon factor)
Example: EST estimates a ground source heat pump in a well-insulated four-bedroom detached home cuts carbon by around 3,500–5,200 kg a year compared with a gas boiler

Rules for New Homes and EPCs

There is currently no ban on replacing a gas boiler in an existing home. New homes in England will need low-carbon heating, such as a heat pump or heat network, under the Future Homes Standard from 24 March 2027.

Energy Performance Certificates are also being reformed. New domestic EPCs will show four headline metrics, including the heating system, with the launch moved to the second half of 2027. How a heat pump affects your EPC or the value of your home depends on the property.

Comfort and Performance

Heat pumps operate differently from gas boilers, which affects home comfort:

Consistent warmth: Heat pumps run at lower temperatures for longer periods, providing steady warmth rather than rapid bursts
Radiator temperatures: Heat pump systems run radiators cooler than gas boilers do, so some rooms may need larger radiators
Hot water: Heat pumps can take longer to heat water tanks, though modern cylinders mitigate this
Cooling capability: Some heat pump systems can also provide cooling in summer

Noise Levels

The outdoor unit of an air source heat pump makes some noise from its fan and compressor, and correct positioning minimises disturbance. In England, a heat pump installed under permitted development must meet the MCS 020(a) noise standard, which your installer should check. Gas boilers are generally quieter but can produce noise from the flue and pump.

When Does Each Option Make Sense?

Gas Boilers Are Best For:

Properties with poor insulation where heat pump efficiency would be compromised
Homes without space for a hot water cylinder
Households with immediate budget constraints and no access to the BUS grant
Properties where radiators can't be upgraded for lower water temperatures
Households planning to move soon

Heat Pumps Are Best For:

Well-insulated properties where efficiency is maximised
Homes with underfloor heating or large radiators
Homes currently heated by LPG, oil or electric storage heaters
Environmentally conscious households prioritising carbon reduction
Owners in England and Wales who qualify for the £7,500 BUS grant
Homes paired with solar panels for further cost reduction

The Optimal Strategy: Insulate First

Regardless of which heating system you choose, improving your home's insulation should be the priority. Better insulation reduces heat loss, meaning you need less energy from any heating source.

For many households, the ideal pathway is:

Check whether you qualify for help with insulation, such as ECO4 or Warm Homes: Local Grant
Get loft and wall insulation done where it is suitable
Then install a heat pump with the £7,500 BUS grant
Optionally add solar panels for more energy independence

ECO4 runs until 31 December 2026; work may be fully or partly funded and you may be asked to contribute. Warm Homes: Local Grant is run by councils in England. The Great British Insulation Scheme closed on 31 March 2026. Insulating first also means your heat pump can be sized for a home that loses less heat.

Making Your Decision

The heat pump vs gas boiler debate doesn't have a universal answer. Your decision should be based on:

Your property's current insulation
How long you plan to stay in the property
Your budget and access to grants
Environmental priorities
Your existing heating system and radiators

For many homeowners in well-insulated properties with long-term plans, a heat pump is worth serious consideration once grants and tariffs are factored in. However, gas boilers remain a practical choice for properties requiring significant preparatory work or households with immediate budget constraints.

Government support differs by path. The Boiler Upgrade Scheme helps with heat pumps, not gas boilers. ECO4 can sometimes include a heating upgrade or a broken-boiler replacement where strict rules are met, but a boiler is not guaranteed.