All MCS-certified installers are listed on the MCS installer finder. MCS certification is a baseline requirement for the BUS grant, but you should also check:
In England, Wales, and Scotland, ASHP installation usually falls under Permitted Development rights — meaning you don’t need planning permission, provided the unit is not on a wall or roof facing a highway, and only one ASHP is installed on the property. Listed buildings require consent. Northern Ireland has slightly different rules — check with your local council.
Insulation requirements
Heat pumps run most efficiently at lower flow temperatures (35–45°C) than a traditional gas boiler (60–80°C). This is fine as long as the heat emitters (radiators or underfloor heating) are large enough to deliver sufficient heat output at that lower temperature. Homes with modern double glazing, loft insulation, and cavity or solid wall insulation are well-suited. If your home is poorly insulated, an installer may size up the radiators as part of the installation — this is normal and can be factored into costs.
Hot water cylinder
ASHPs require a hot water cylinder — they cannot store hot water in a combi-style unit the way a gas boiler can. If you currently have a combi boiler, your installer will need to add a cylinder and associated pipework. For more detail on sizing and cylinder options, see our guide to heat pump hot water cylinders.
Air source heat pump costs in the UK
Understanding the true cost means separating the unit, the installation labour, any required upgrades, and then netting off the available grant. Here is a realistic breakdown for 2026.
| Cost component | Typical range | Notes |
|---|---|---|
| ASHP unit (5–10 kW, mid-range brand) | £3,500 – £6,000 | Leading brands include Vaillant, Samsung, Mitsubishi, Daikin, Nibe |
| Installation labour | £2,000 – £4,000 | Includes commissioning and handover; higher in London and SE England |
| Hot water cylinder (if needed) | £600 – £1,500 | Not required if you already have a cylinder |
| Radiator upgrades (if needed) | £0 – £3,000 | Often not all radiators need upgrading; depends on existing emitters |
| Electrical upgrades | £0 – £800 | Usually just a dedicated circuit for the heat pump |
| Total installed cost (gross) | £8,000 – £18,000 | Most homes land between £10,000 and £14,000 |
| BUS grant | −£7,500 | Applied by installer; reduces upfront cost directly |
| Typical net cost after grant | £5,500 – £10,500 | Assuming grant eligibility |
For a full cost breakdown including running cost comparisons, see our dedicated heat pump costs guide for 2026. Savings vary depending on property size, insulation, and energy tariff.
The Boiler Upgrade Scheme: what you need to know
The Boiler Upgrade Scheme (BUS), administered by Ofgem, provides a £7,500 voucher toward the cost of an ASHP installation. The voucher is applied by your MCS-certified installer — you never see the money directly; it simply reduces your invoice. Key eligibility conditions:
- The property must be in England or Wales (Scotland has its own scheme)
- You must have a valid EPC (Energy Performance Certificate) with no outstanding recommendations for cavity wall insulation or loft insulation
- The installer must be MCS-certified and registered with the BUS scheme
- You cannot claim the grant for a replacement ASHP (only new ASHP installations or replacing a fossil-fuel heating system)
Scotland has the Home Energy Scotland Grant and Loan scheme, which can provide up to £7,500 as a grant and a further £6,000 as an interest-free loan. The Energy Saving Trust administers this for the Scottish Government.
For the full picture on grants, including ECO4 and local authority schemes, see our BUS grant guide.
Running costs and efficiency: what to realistically expect
Running cost comparisons require a honest look at the current electricity-to-gas price ratio. In 2026, electricity from the grid costs approximately 25p/kWh under the Ofgem cap, while gas is around 6p/kWh. This means that even with a COP of 3.0, the cost per unit of heat from a heat pump (≈ 8.3p/kWh of heat) is broadly comparable to gas (≈ 7.5p/kWh of heat at 80% boiler efficiency). For homes heating with oil or LPG — where fuel costs are higher — the economics are substantially more favourable.
The picture improves considerably if you use a heat-pump-optimised electricity tariff. Octopus Energy’s Cosy Octopus tariff offers electricity at reduced rates during off-peak periods, which heat pumps can exploit by pre-heating the home and hot water cylinder overnight. Some customers report effective electricity costs under 15p/kWh on average when running their heat pump on such a tariff — that’s a clear win over gas.
For a detailed breakdown of projected running costs by home type and fuel, see our heat pump running costs guide.
Choosing a heat pump and installer
The single most important decision is choosing a good installer — not a particular brand of heat pump. A well-designed and commissioned system from a second-tier brand will outperform a badly installed premium-brand unit every time.
All MCS-certified installers are listed on the MCS installer finder. MCS certification is a baseline requirement for the BUS grant, but you should also check:
- Whether the installer has specific ASHP experience (not just Gas Safe heritage)
- Whether they carry out a full heat loss calculation before quoting (this is non-negotiable)
- Whether they provide a commissioning report and MCS warranty documentation
- Reviews from previous heat pump customers (not just boiler work)
Always get at least three quotes. For guidance on evaluating quotes and spotting red flags, see our guide to finding the best heat pump installers. It is also worth cross-referencing whether a smart thermostat and controls package is included — see SmartHomeWise’s guide to smart thermostats for heat pumps for recommendations on compatible controls.
Is an air source heat pump worth it for your home?
For most UK homes replacing oil, LPG, or electric storage heating: yes, clearly. The BUS grant substantially reduces upfront cost, running costs are lower, and the carbon footprint of the home drops by 30–50% immediately. For gas homes, the financial case is more nuanced — running cost savings are modest in 2026, but the grant still makes the net cost attractive, and gas prices are expected to remain volatile. For anyone whose boiler is reaching end of life, an ASHP is worth serious consideration as a like-for-like replacement rather than a new boiler.
For an honest assessment of the pros and cons, see our article Is a heat pump worth it in the UK? — and for a head-to-head comparison with a new gas boiler, see heat pump vs gas boiler 2026.
Air source heat pumps have become the UK’s default answer to replacing a gas or oil boiler — and for good reason. In 2026, more than 70,000 are being installed every year, the £7,500 Boiler Upgrade Scheme grant is still available, and real-world performance data shows a well-installed system can achieve a seasonal COP of 3.0–3.5, meaning every £1 of electricity produces £3–£3.50 of heat. This guide covers everything: how they work, whether your home is suitable, what they cost, and how to get started without being ripped off.
This article contains affiliate links. If you buy through them, we may earn a small commission at no extra cost to you. This doesn’t affect our editorial independence — we only recommend products we’d genuinely suggest to a friend.
Key Takeaways
- Air source heat pumps extract heat from outdoor air and move it indoors — they don’t generate heat by burning anything
- The £7,500 BUS grant brings the typical net cost down to £8,000–£12,000 for most homes
- Most UK houses are suitable, including those with radiators — oversized radiators or UFH both work well
- Oil and LPG homes typically save £400–£1,200/year on running costs; gas home savings are more modest
- You must use an MCS-certified installer to qualify for the BUS grant
What is an air source heat pump and how does it work?
An air source heat pump (ASHP) is a device that extracts heat from outdoor air and transfers it into your home’s heating and hot water system. It works on the same principle as a refrigerator in reverse: a refrigerant circulates between an outdoor unit and an indoor unit, absorbing heat from outside air (even at temperatures as low as -15°C) and releasing it into your heating circuit at a usable temperature.
The key metric is the coefficient of performance (COP): the ratio of heat output to electricity input. A system achieving a COP of 3.0 produces 3 kWh of heat for every 1 kWh of electricity consumed. In seasonal terms — accounting for varying outdoor temperatures across a full year — this is called the SCOP (Seasonal COP). Most modern ASHPs achieve SCOP 2.5–4.0 in UK conditions, depending on the system design and the temperature they’re running at.
There are two main types of ASHP for residential heating:
- Monobloc: all the refrigerant cycle components are in the outdoor unit. A water pipe runs into the house. These are simpler, less expensive, and the most common residential choice.
- Split system: the refrigerant cycle is split between an outdoor unit and an indoor unit. More flexible for siting but requires F-Gas-qualified engineers for installation.
For a deep dive into how performance varies in winter, see our guide to heat pump winter performance.
Is my home suitable for an air source heat pump?
The short answer: probably yes, if you have a garden or space on an external wall, and the building has at least basic insulation. The longer answer involves checking a few things.
Space for the outdoor unit
The external unit needs to be mounted on an external wall or ground base with reasonable airflow around it. Most UK houses — detached, semi-detached, or terraced with a rear garden — have no problem meeting this. Flats are the main exception: planning constraints and shared walls make ASHP installation difficult in most flats, though some ground-floor properties may still be viable.
Planning permission
In England, Wales, and Scotland, ASHP installation usually falls under Permitted Development rights — meaning you don’t need planning permission, provided the unit is not on a wall or roof facing a highway, and only one ASHP is installed on the property. Listed buildings require consent. Northern Ireland has slightly different rules — check with your local council.
Insulation requirements
Heat pumps run most efficiently at lower flow temperatures (35–45°C) than a traditional gas boiler (60–80°C). This is fine as long as the heat emitters (radiators or underfloor heating) are large enough to deliver sufficient heat output at that lower temperature. Homes with modern double glazing, loft insulation, and cavity or solid wall insulation are well-suited. If your home is poorly insulated, an installer may size up the radiators as part of the installation — this is normal and can be factored into costs.
Hot water cylinder
ASHPs require a hot water cylinder — they cannot store hot water in a combi-style unit the way a gas boiler can. If you currently have a combi boiler, your installer will need to add a cylinder and associated pipework. For more detail on sizing and cylinder options, see our guide to heat pump hot water cylinders.
Air source heat pump costs in the UK
Understanding the true cost means separating the unit, the installation labour, any required upgrades, and then netting off the available grant. Here is a realistic breakdown for 2026.
| Cost component | Typical range | Notes |
|---|---|---|
| ASHP unit (5–10 kW, mid-range brand) | £3,500 – £6,000 | Leading brands include Vaillant, Samsung, Mitsubishi, Daikin, Nibe |
| Installation labour | £2,000 – £4,000 | Includes commissioning and handover; higher in London and SE England |
| Hot water cylinder (if needed) | £600 – £1,500 | Not required if you already have a cylinder |
| Radiator upgrades (if needed) | £0 – £3,000 | Often not all radiators need upgrading; depends on existing emitters |
| Electrical upgrades | £0 – £800 | Usually just a dedicated circuit for the heat pump |
| Total installed cost (gross) | £8,000 – £18,000 | Most homes land between £10,000 and £14,000 |
| BUS grant | −£7,500 | Applied by installer; reduces upfront cost directly |
| Typical net cost after grant | £5,500 – £10,500 | Assuming grant eligibility |
For a full cost breakdown including running cost comparisons, see our dedicated heat pump costs guide for 2026. Savings vary depending on property size, insulation, and energy tariff.
The Boiler Upgrade Scheme: what you need to know
The Boiler Upgrade Scheme (BUS), administered by Ofgem, provides a £7,500 voucher toward the cost of an ASHP installation. The voucher is applied by your MCS-certified installer — you never see the money directly; it simply reduces your invoice. Key eligibility conditions:
- The property must be in England or Wales (Scotland has its own scheme)
- You must have a valid EPC (Energy Performance Certificate) with no outstanding recommendations for cavity wall insulation or loft insulation
- The installer must be MCS-certified and registered with the BUS scheme
- You cannot claim the grant for a replacement ASHP (only new ASHP installations or replacing a fossil-fuel heating system)
Scotland has the Home Energy Scotland Grant and Loan scheme, which can provide up to £7,500 as a grant and a further £6,000 as an interest-free loan. The Energy Saving Trust administers this for the Scottish Government.
For the full picture on grants, including ECO4 and local authority schemes, see our BUS grant guide.
Running costs and efficiency: what to realistically expect
Running cost comparisons require a honest look at the current electricity-to-gas price ratio. In 2026, electricity from the grid costs approximately 25p/kWh under the Ofgem cap, while gas is around 6p/kWh. This means that even with a COP of 3.0, the cost per unit of heat from a heat pump (≈ 8.3p/kWh of heat) is broadly comparable to gas (≈ 7.5p/kWh of heat at 80% boiler efficiency). For homes heating with oil or LPG — where fuel costs are higher — the economics are substantially more favourable.
The picture improves considerably if you use a heat-pump-optimised electricity tariff. Octopus Energy’s Cosy Octopus tariff offers electricity at reduced rates during off-peak periods, which heat pumps can exploit by pre-heating the home and hot water cylinder overnight. Some customers report effective electricity costs under 15p/kWh on average when running their heat pump on such a tariff — that’s a clear win over gas.
For a detailed breakdown of projected running costs by home type and fuel, see our heat pump running costs guide.
Choosing a heat pump and installer
The single most important decision is choosing a good installer — not a particular brand of heat pump. A well-designed and commissioned system from a second-tier brand will outperform a badly installed premium-brand unit every time.
All MCS-certified installers are listed on the MCS installer finder. MCS certification is a baseline requirement for the BUS grant, but you should also check:
- Whether the installer has specific ASHP experience (not just Gas Safe heritage)
- Whether they carry out a full heat loss calculation before quoting (this is non-negotiable)
- Whether they provide a commissioning report and MCS warranty documentation
- Reviews from previous heat pump customers (not just boiler work)
Always get at least three quotes. For guidance on evaluating quotes and spotting red flags, see our guide to finding the best heat pump installers. It is also worth cross-referencing whether a smart thermostat and controls package is included — see SmartHomeWise’s guide to smart thermostats for heat pumps for recommendations on compatible controls.
Is an air source heat pump worth it for your home?
For most UK homes replacing oil, LPG, or electric storage heating: yes, clearly. The BUS grant substantially reduces upfront cost, running costs are lower, and the carbon footprint of the home drops by 30–50% immediately. For gas homes, the financial case is more nuanced — running cost savings are modest in 2026, but the grant still makes the net cost attractive, and gas prices are expected to remain volatile. For anyone whose boiler is reaching end of life, an ASHP is worth serious consideration as a like-for-like replacement rather than a new boiler.
For an honest assessment of the pros and cons, see our article Is a heat pump worth it in the UK? — and for a head-to-head comparison with a new gas boiler, see heat pump vs gas boiler 2026.