- Guide price
- From £9,500 inc VAT
- Survey
- Free home survey for installation enquiries
- Coverage
- England, Wales, Scotland and Northern Ireland
Replacing a gas boiler with a heat pump means removing the boiler and installing an air-to-water heat pump that heats your radiators and a stored hot water cylinder instead. Most UK homes heat with mains gas, so this is the switch many households are weighing up, and the existing radiators and pipework can often be reused with some changes. What needs most planning depends on the type of boiler you have now.
If you have a combi, there is no cylinder at the moment, so the first question is where one can go. If you have a system or regular boiler, you already have a cylinder, but it is unlikely to suit a heat pump, which needs a larger internal coil to heat water at lower temperatures. Regular boilers also have tanks in the loft that can usually be taken out, freeing space.
The other decision is the gas supply. If gas is used for nothing else — no gas hob, fire or cooker — you can have the supply capped and the meter removed, which ends the gas standing charge of about £108 a year at current price cap rates. We talk through each choice at the survey so you can decide before you accept the quote.
Who it suits
- Combi owners who can find space for a hot water cylinder
- System or regular boiler homes with an existing airing cupboard
- Households ready to give up gas entirely and drop the standing charge
- Boilers that are old, unreliable or due for replacement
- Homes in England and Wales eligible for the Boiler Upgrade Scheme
Things to consider
- A combi swap needs room for a cylinder, which can mean giving up a cupboard.
- Keeping a gas hob or fire means keeping the gas meter and its standing charge.
- Running costs depend on insulation, flow temperature and tariff, so the comparison with gas differs from home to home.
- Hot water is stored rather than instant, so the cylinder must be sized for how your household uses it.
Where does the cylinder go if I have a combi boiler?
A heat pump needs a hot water cylinder because, unlike a combi, it cannot heat water instantly as you run the tap. For a typical family home the cylinder holds about 150–250 litres and usually needs a space roughly 600–700 mm square and up to about 1.8 m tall, depending on the model.
Common locations are an existing cupboard, a utility room, a garage or under the stairs. Slimline models help in awkward spaces, and some indoor units combine the cylinder and controls in one tall cabinet the size of a fridge-freezer. The survey measures the options and checks there is a route for pipework and for the cylinder's safety discharge pipe.
What happens to my gas supply and meter?
If you no longer need gas at all, the supply can be capped and the meter removed, ending the gas standing charge. At the October to December 2026 price cap that charge is 29.68p a day, or about £108 a year.
Capping the pipe at the old boiler position is done by a registered gas engineer during the installation. Removing the meter itself is arranged through your gas supplier, usually once the heat pump is running. If you keep a gas hob or fire, the supply stays and so does the standing charge, which is why some households switch to an induction hob at the same time. The boiler and flue are taken out and the flue opening is sealed.
Will a heat pump cost more or less to run than my gas boiler?
It depends on how efficiently the heat pump runs in your home, which comes down to insulation, flow temperature and your electricity tariff. At the October to December 2026 price cap, a heat pump with a seasonal efficiency (SCOP) of 3.5 delivers heat for about 7.5p per kWh, and at a SCOP of 3.0 about 8.8p. A 90% efficient gas boiler delivers heat for about 8.9p per kWh.
On current figures, a well-designed system running at low flow temperatures can deliver heat for about the same as gas or a little less, before counting a standing charge you may no longer pay. A system running hot in a draughty house will cost more. Heat pump tariffs from some suppliers can lower costs further, and the survey estimate is based on your home rather than an average.
Can I reuse my existing radiators and pipework?
Often, yes: most gas-heated homes keep the majority of their radiators and pipes, and the survey identifies the few rooms that need a larger radiator. The system is flushed clean before the heat pump is connected.
Very narrow microbore pipework, common in some homes built from the 1970s onwards, can restrict the flow a heat pump needs. Upgrading it has a guide price of £1,500–£3,500, installed and including VAT, and is only included where the design shows it is needed.
What's included
- Free survey with heat loss calculation and cylinder siting
- Removal of the gas boiler, flue and any loft tanks
- Capping of the gas pipe at the boiler position where you are giving up gas
- Heat pump cylinder, outdoor unit and weather compensation controls
- System flush and radiator upgrades where the design calls for them
- Commissioning, MCS certificate and grant application in England and Wales where eligible
Gas boiler to heat pump guide prices
| Home | Typical size | Installed guide price | After £7,500 grant |
|---|---|---|---|
| 1–2 bedroom flat or small terrace | 4–5 kW | £9,500–£12,500 | £2,000–£5,000 |
| 2–3 bedroom terrace or semi | 5–7 kW | £10,500–£13,500 | £3,000–£6,000 |
| 3 bedroom semi or small detached | 6–9 kW | £12,000–£15,500 | £4,500–£8,000 |
| 4 bedroom detached | 8–12 kW | £14,000–£18,000 | £6,500–£10,500 |
| 5+ bedroom or larger older house | 11–16 kW | £16,500–£22,500 | £9,000–£15,000 |
Installed, inc VAT: unit, cylinder, controls, minor pipework and commissioning.
Replacing a gas boiler with a heat pump questions
Can a heat pump replace a combi boiler?
Yes, but you need room for a hot water cylinder, because heat pumps store hot water rather than heating it on demand. Most homes find a space in a cupboard, utility room, garage or under the stairs, and compact or combined indoor units help where space is tight. The survey measures the options first, so you know where everything will go before you accept the quote.
Should I have my gas meter removed?
If gas is used for nothing else, removing the meter ends the gas standing charge, which is about £108 a year at the October to December 2026 price cap. If you still cook on gas or have a gas fire, you will need to keep the supply. Meter removal is arranged through your gas supplier, usually once the heat pump is running; the pipe at the boiler position is capped during the installation.
Is there a grant to replace a gas boiler with a heat pump?
In England and Wales, the Boiler Upgrade Scheme gives £7,500 towards an air-to-water heat pump that replaces a gas boiler, for eligible owners of existing homes. The MCS-certified installer applies to Ofgem and deducts the grant from your quote, and Ofgem contacts you to confirm. Scotland has separate Home Energy Scotland funding, and Northern Ireland has no dedicated homeowner grant at present.
What if my gas boiler is fairly new?
A newer boiler can still be replaced, but the timing is worth weighing. Some owners switch when the boiler needs a major repair; others prefer to plan the change for a convenient time. Across the UK, heat pump installation is zero-rated for VAT until 31 March 2027. A hybrid system, which keeps the boiler alongside a heat pump, is another option, though it is not eligible for the Boiler Upgrade Scheme in England and Wales.
Will my hot water run out with a heat pump?
Not if the cylinder is sized properly for your household. The survey asks how many people live in the home, how many bathrooms you have and whether you prefer baths or showers, then sizes the cylinder to suit. The heat pump reheats the cylinder on a schedule, often overnight and again during the day, and an immersion heater acts as a backup.
Do I need to replace the cylinder I already have?
Usually, yes. Older cylinders have a small internal coil designed for water from a boiler at around 60–70°C, and they cannot take in heat quickly enough at the lower temperatures a heat pump runs at. A heat pump cylinder has a larger coil. On its own, a cylinder supplied and fitted has a guide price of £1,200–£2,200, installed and including VAT, though it is normally part of the full system price.