Heat pump vs gas boiler: which costs more?
Upfront, a gas boiler is far cheaper: a new boiler is typically about £3,000 fitted, while an air source heat pump is typically £11,000 before the £7,500 government grant, so roughly £3,500 to £6,000 after it. Over time a heat pump can be cheaper to run and is lower-carbon, but the right choice depends on your home, insulation and tariff.
Air source heat pump vs New boiler: the cost
| Option | Range | Typical | Priced |
|---|---|---|---|
| Air source heat pump | £7,000 to £20,000 | £13,000 | before grant |
| New boiler | £1,800 to £4,800 | £3,000 | supplied and fitted |
Costwise guide prices, reviewed June 2026, not quotes. Note the two are quoted on different bases, so the figures above are not a like-for-like comparison on their own.
Air source heat pump vs New boiler: the difference
| Factor | How they compare |
|---|---|
| Upfront cost | Boiler wins: about £3,000 fitted, versus about £11,000 before the grant for a heat pump. |
| After grants | The £7,500 Boiler Upgrade Scheme grant narrows the gap to roughly £3,500 to £6,000 net for a heat pump. |
| Running cost | A heat pump delivers around three units of heat per unit of electricity, so it can be cheaper to run, but this depends heavily on tariff and insulation. |
| Best for | Boiler: lowest upfront cost and a like-for-like swap. Heat pump: lower carbon and running cost in a well-insulated home, with the grant. |
The £7,500 grant is what this decision turns on
Before any grant the gap is wide. A new gas boiler is £1,800 to £4,500 supplied and fitted, typically about £3,000. An air source heat pump is £7,000 to £20,000 before the grant, typically about £13,000. Nothing about the installation itself closes a gap that size.
The grant changes the arithmetic rather than the price. gov.uk pays £7,500 towards an air source heat pump, and the scheme is open to people in England and Wales. Take that off a typical 3 bed install of £9,000 to £13,000 and you are left with roughly £1,500 to £5,500 to find, against £1,800 to £4,500 for a boiler. The two bands now overlap, although typical against typical the boiler is still the cheaper job.
If your home is heated by oil or LPG and has no mains gas connection, gov.uk lists a further £1,500 on top, until March 2027. That takes a typical net figure to about £4,000, inside the band a gas boiler occupies. Scotland and Northern Ireland run their own separate schemes, so do not budget for this one there.
The grant only exists if your installer is MCS certified
The £7,500 never reaches your bank account. It is claimed by an MCS certified installer and taken off your invoice, so the figure you sign should already be net of it. Ask to see the grant as a line on the quote, and ask for the MCS certificate number.
This is where a cheaper quote can cost you money. A firm without MCS certification can undercut a certified one on the same install and still leave you £7,500 worse off, because the grant is only payable through a certified installer. Refrigerant handling means the engineer also needs to be F-Gas registered.
The boiler equivalent is Gas Safe. By law anyone you pay to fit or work on a gas boiler must be on the Gas Safe Register, and an unregistered install voids the warranty and your insurance as well. On either job, check the registration before you compare the prices.
Running costs turn on two numbers, not one
There is no honest single figure for what a heat pump saves, so we do not publish one. What decides it is the ratio between what you pay per unit of electricity and per unit of gas, set against the efficiency the heat pump actually achieves.
A well designed heat pump delivers around three units of heat for every unit of electricity. So if electricity costs roughly three times as much per unit as gas, running costs land about level. A cheaper or off-peak tariff, or a system designed to run at a low flow temperature, and the heat pump pulls ahead. A system pushed to run hot in a poorly insulated house, and it does not.
That efficiency is not a fixed number. It falls as the flow temperature rises and it dips in very cold spells. Ask your installer for the predicted seasonal efficiency in their design, then put it against the unit rates on your own bill. That is the only version of the sum that applies to your house.
What the house may need before a heat pump fits
A heat pump runs at a lower flow temperature than a boiler, so some radiators need to be larger to give out the same heat. Our guide prices radiator upgrades or a new cylinder at £1,500 to £4,000 on top of the install. A good installer works out which rooms genuinely need it from the heat loss survey instead of replacing the lot, and it is usually the larger rooms rather than every radiator you own.
Coming off a combi you will usually need a hot water cylinder, roughly £500 to £1,500 fitted, plus somewhere to put it. That is space a combi gave you back, so it is a real cost even where the money is modest.
Insulation comes first for a reason. A lower heat loss figure means a smaller, cheaper unit and fewer radiator changes, so loft or cavity work can come off the heat pump quote as well as the bills. If your walls are solid and uninsulated and there is no route to fixing that, it is a genuine argument for a boiler.
When each one is the right answer
Fit a gas boiler if the old one has failed and you need heat this week. A straight combi swap is £1,800 to £2,800 and a day's work, where a heat pump is two to five days on site after a survey and a system design. Fit a boiler too if the house is solid walled and uninsulated with no way to change that, if there is nowhere outside with reasonable airflow, or if the upfront gap is still unaffordable after the grant. For a lot of British housing the boiler is still the pragmatic answer.
Fit a heat pump if the house is reasonably insulated, there is space outside, you qualify for the grant, and you are replacing on your own timetable rather than in an emergency. The outdoor unit needs space with reasonable airflow and a sensible route for pipework back into the house, and it makes a low hum, so where it sits matters to you and to a neighbour. Check the planning position for your own property before you order anything. If your boiler still works, that is the window to plan this properly rather than decide it on a cold morning.
Common questions
Not to install: a heat pump costs more upfront even after the £7,500 grant. It can be cheaper to run, but whether it saves money overall depends on your tariff, insulation and how the system is set up.
It narrows the gap a lot. A typical heat pump of £9,000 to £13,000 before the grant works out around £2,500 to £6,000 after, versus about £1,800 to £4,500 for a boiler, so the boiler is usually still cheaper upfront.
Only if your home is heated by oil or LPG and has no mains gas connection. gov.uk lists a further £1,500 towards an air source or ground source heat pump for those properties, until March 2027, on top of the standard £7,500. That takes a typical £13,000 install to about £4,000 out of pocket. Homes already on mains gas get the £7,500 only.
Not necessarily, but it often pays to. A lower heat loss figure means a smaller, cheaper unit and fewer radiators to upsize, so insulating first can reduce the heat pump quote as well as the bills. The Boiler Upgrade Scheme sets its own eligibility conditions, so check those on gov.uk before you count on the grant.
A straight boiler swap is usually a single day, or two to three days if you are converting from a system boiler or moving the boiler to a new spot. An air source heat pump is two to five days on site, after a heat loss survey and a system design that happen before anyone turns up. That difference matters most in a breakdown: a boiler can be fitted this week, a heat pump cannot.
Often for most of the house, rather than all of it. Because a heat pump runs at a lower flow temperature, a radiator has to be larger to give out the same heat, so the heat loss survey decides which rooms need changing. Our guide prices radiator upgrades or a new cylinder at £1,500 to £4,000 on top. It is usually the larger rooms that need attention, not every radiator you own.
Nothing like the Boiler Upgrade Scheme, but some low income households can get a free or heavily subsidised replacement through ECO4, which runs until 31 December 2026. Eligibility usually turns on receiving a qualifying benefit such as Universal Credit or Pension Credit and living in a less efficient home, often EPC band D to G. Some councils refer other households through ECO4 Flex. Most households do not qualify and pay privately, around £3,000 fitted.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing.