If you are thinking about replacing your boiler in 2026, you have probably come across the combi boiler vs heat pump debate. Government campaigns, energy companies, and the media have pushed heat pumps heavily over the past couple of years — and for some homes, they genuinely are the right choice. But for most UK homeowners right now, the reality is a lot more nuanced than the headlines suggest.
This guide does not take sides. What it does is give you the honest facts — upfront costs, running costs, suitability requirements, and what each option actually means for your home in the real world. The team at Gorilla Heat has put this together to help you make an informed decision — not to push you toward one option or the other.
2026 Fast Facts: Combi Boiler vs Heat Pump
Before the detail, here is a side-by-side snapshot of where things stand in 2026:
| Combi Boiler | Air Source Heat Pump | |
| Install cost | £1,800 – £3,500 | £12,000 – £16,000 |
| After BUS grant | No grant available | £4,500 – £8,500 |
| Gas price (Apr 2026) | 6.04p / kWh | N/A |
| Electricity price (Apr 2026) | N/A | 23.18p / kWh |
| Efficiency rating | 90–95% (A-rated) | 250–400% (COP 2.5–4) |
| Works in all UK homes | Yes | Needs good insulation |
| Installation time | 1 day | 3–5 days |
| Radiator upgrades needed | No | Often yes |
| Annual savings vs old boiler | £200 – £350 / yr | £120 – £380 / yr* |
How Each System Works
Combi Boiler
A combi boiler burns natural gas to heat water on demand directly from the mains. It provides both central heating and hot water from a single compact unit, with no need for a separate cylinder or storage tank. Modern A-rated condensing combis operate at 90–95% efficiency, meaning very little of the gas burned is wasted. They work in any UK property connected to the gas grid, regardless of insulation level or radiator size.
Air Source Heat Pump
An air source heat pump extracts heat from outdoor air and transfers it inside using a refrigerant cycle — similar in principle to a fridge operating in reverse. Because it moves heat rather than generating it by burning fuel, it can deliver 2.5 to 4 units of heat for every unit of electricity consumed, giving a Coefficient of Performance (COP) of 2.5 to 4. This high efficiency figure is frequently cited as the reason heat pumps are better — but the critical caveat is that electricity costs nearly four times more per unit than gas in 2026, which significantly affects the real-world running cost comparison.
Running Costs: The Honest Comparison
This is where the heat pump debate gets complicated — and where a lot of promotional material is misleading. Heat pumps are highly efficient, but efficiency alone does not determine your bill. What matters is the cost of the energy they consume.
In April 2026, gas costs 6.04p per kWh and electricity costs 23.18p per kWh — a ratio of approximately 3.8 to 1. For a heat pump to match the running costs of a modern combi boiler, it needs to achieve a COP of at least 3.8 consistently throughout the year. In practice, most UK heat pumps achieve an annual average COP of 2.5 to 3.0 — which in 2026 energy pricing often means higher running costs than a new combi boiler, not lower ones.
The exception is well-insulated homes with large radiators or underfloor heating, where a heat pump can maintain a high COP consistently. In those homes, the sums can work in the heat pump’s favour.
| Home Type | Combi Annual Cost | Heat Pump Annual Cost |
| Well insulated (EPC A/B) | ~£900 – £1,100 | ~£800 – £1,000 |
| Average insulation (EPC C/D) | ~£1,100 – £1,400 | ~£1,200 – £1,600 |
| Poor insulation (EPC E/F/G) | ~£1,400 – £1,800 | ~£2,000 – £2,800 |
Upfront Installation Cost
The upfront cost difference between a combi boiler and a heat pump remains substantial in 2026, even after the government’s Boiler Upgrade Scheme (BUS) grant is applied.
• New combi boiler installed: £1,800 to £3,500
• Air source heat pump (before grant): £12,000 to £16,000
• BUS grant (England & Wales, extended to 2028): £7,500
• Air source heat pump (after grant): £4,500 to £8,500
Even after the £7,500 Boiler Upgrade Scheme grant, the cheapest heat pump installation is typically £1,000 to £5,000 more expensive than a quality combi boiler. And that is before factoring in potential additional costs for larger radiators, underfloor heating upgrades, or a hot water cylinder — all of which may be required for a heat pump to perform correctly in older properties.
Is Your Home Suitable for a Heat Pump?
This is the most important question to answer before considering a heat pump — and it is one that does not get asked nearly enough in the broader public conversation. Heat pumps work best in homes that meet specific criteria. Without them, performance and running costs suffer significantly.
| Heat pump works well if… | Combi boiler is the better fit if… |
| EPC rating A, B, or well-insulated C | EPC rating C, D, E, F, or G |
| Large radiators or underfloor heating already fitted | Standard radiators throughout |
| Detached or semi with good wall and loft insulation | Terraced house or flat with limited insulation options |
| Off gas grid — currently using oil or LPG | Already connected to the gas grid |
| Long-term owner — planning to stay 10+ years | Shorter-term ownership or rental property |
| Budget available for full installation including upgrades | Budget is the primary consideration |
The honest truth is that the majority of UK homes — particularly older terraced and semi-detached properties built before the 1990s — are not currently well-suited to heat pumps without significant additional investment. Improving insulation, upgrading radiators, and fitting a hot water cylinder can add thousands of pounds to the overall cost and extend the installation timeframe considerably.
What Is the Boiler Upgrade Scheme?
The Boiler Upgrade Scheme (BUS) is a UK government grant that provides £7,500 towards the installation of an air source heat pump, or £5,000 towards a ground source heat pump. The scheme is available in England and Wales and has been extended to 2028.
To be eligible, the property must:
• Have a valid Energy Performance Certificate (EPC) with no outstanding recommendations for loft or cavity wall insulation
• Be in England or Wales
• Use a MCS-certified heat pump installer
• Not have received a previous BUS grant for the same property
Note that the BUS grant does not apply to new gas boiler installations. There is no government grant currently available for combi boiler replacement — though the upfront cost of a new boiler is significantly lower regardless.
So Which Is Better — Combi Boiler or Heat Pump?
The honest answer is: it depends entirely on your home, your budget, and your long-term plans.
Choose a combi boiler if: your home is connected to the gas grid, you have standard radiators, your insulation is average or below, your budget is under £4,000, or you need a replacement quickly and reliably. For the majority of UK homeowners in 2026, a new A-rated combi boiler from a reputable brand remains the most practical, cost-effective, and immediately available solution.
Consider a heat pump if: your home is well-insulated, you already have or are willing to upgrade to large radiators or underfloor heating, you are off the gas grid, you are planning a long-term stay in the property, and you can absorb the higher upfront cost — even after the BUS grant. Heat pumps are genuinely the right choice for some homes. But that group is still a minority of UK housing stock in 2026.
The worst outcome is a heat pump installed in a home that is not ready for it — poor insulation, undersized radiators, and a high electricity-to-gas price ratio can result in an expensive system that costs more to run than the old gas boiler it replaced. An honest assessment of your property is essential before committing.
Not Sure What Is Right for Your Home? Talk to Gorilla Heat
At Gorilla Heat, we will always give you a straight answer — even if that means telling you a combi boiler is the better option for your home right now. We are a veteran-owned, family-run business with over 20 years of experience, Gas Safe certified and Worcester Bosch approved installers.
We install new boilers acrossScunthorpe, Brigg, and across North Lincolnshire and East Yorkshire — with 0% finance available on all installations.
Get in touch with our team today for a free, no-obligation assessment. We will look at your home honestly and tell you exactly what makes sense for your situation.
Frequently Asked Questions
Is a heat pump cheaper to run than a combi boiler in 2026?
Not necessarily. Heat pumps are highly efficient, but electricity costs around 23p per kWh in 2026 compared to 6p for gas. For a heat pump to match a combi boiler’s running costs, it needs to achieve a COP of at least 3.8 throughout the year. Most UK heat pumps average 2.5 to 3.0, meaning running costs are often similar to or higher than a new combi boiler — unless the home is exceptionally well insulated.
What is the Boiler Upgrade Scheme and can I use it?
The Boiler Upgrade Scheme (BUS) is a government grant offering £7,500 towards an air source heat pump installation. It is available in England and Wales and has been extended to 2028. To qualify, your property needs a valid EPC with no outstanding insulation recommendations, and the installation must be carried out by a MCS-certified installer. The grant does not apply to new gas boiler installations.
How much does an air source heat pump cost in the UK in 2026?
Air source heat pump installation costs range from £12,000 to £16,000 before the government grant. After the £7,500 Boiler Upgrade Scheme grant, the net cost is typically £4,500 to £8,500. Additional costs for radiator upgrades, insulation improvements, or a hot water cylinder can add several thousand pounds on top of this.
Can I get a heat pump if I have a gas boiler?
Yes — switching from a gas boiler to a heat pump is possible, but it is a significant undertaking. Your existing radiators may need to be upgraded to larger ones, a hot water cylinder will need to be installed, and your home’s insulation should be assessed first. For most homes currently on the gas grid with average insulation, a new combi boiler remains the more practical and cost-effective option in 2026.
Which is better for the environment — a combi boiler or a heat pump?
A heat pump is better for the environment in most scenarios, provided it achieves a good COP and the electricity grid it draws from is powered by a sufficient proportion of renewables. As the UK grid becomes greener over time, the environmental case for heat pumps strengthens. A modern A-rated combi boiler is still significantly more efficient than an older gas boiler, and represents a meaningful environmental improvement for homes where a heat pump is not yet a viable option.