Strong fit
Roughly half the homes I survey look ready for a heat pump.
Heat pumps and boilers
Heat Pump vs Gas Boiler: Which Is Better for Your Home?
A heat pump wins on some homes and a gas boiler remains the practical choice on others. The useful comparison starts with the property, not the team scarf.
- 23 yearsin plumbing & heating
- 14 yearssurveying heating systems
- 5,000+properties surveyed
- 50 / 30 / 15 / 5real survey-fit pattern
Insight by Vector Heat
For a suitable home, a properly designed heat pump offers low-carbon heating, steady comfort and running costs that can compete with gas. A gas boiler usually costs less to replace like for like and can be the more practical short-term choice where the property, budget or homeowner does not suit a heat-pump project.
My answer after years of surveying both systems is not “heat pumps everywhere” or “boilers forever”. It is: measure the house, understand the household and show the numbers.
Key points
Small changes
About three in ten need a modest amount of system work.
Larger project
Some need significant emitter, pipework or fabric upgrades.
Poor fit
A small group genuinely may not make practical sense.
Those percentages are my experience-based survey pattern, not a national statistic. They describe the homes I see and are included to show that suitability is a spectrum.
Heat Pump vs Gas Boiler: Side-by-Side
| Question | Air-to-water heat pump | Gas boiler |
|---|---|---|
| How does it make heat? | Moves heat from outdoor air into heating water using electricity. | Burns mains gas and transfers combustion heat into heating water. |
| Typical system style | Longer, lower-temperature operation with weather compensation. | Can run at higher water temperatures and often in shorter periods. |
| Domestic hot water | Normally stored in a cylinder. | Can be instant from a combi or stored with a system/heat-only boiler. |
| Outdoor requirement | Needs a suitable outdoor unit position and route indoors. | Needs a legal flue terminal and gas supply. |
| Upfront project | More design-led; may include emitters, cylinder and electrical work. | Often simpler and cheaper for a like-for-like replacement. |
| Running cost | Depends strongly on seasonal efficiency and electricity tariff. | Depends on gas price, boiler efficiency, controls and flow temperature. |
| Carbon at the home | No on-site combustion; electricity's carbon intensity continues to change. | Produces carbon dioxide by burning fossil gas. |
| Comfort | Steady, even heat when designed and controlled well. | Familiar response and hot radiators, though it can also be optimised to run cooler. |
Is a Heat Pump Cheaper to Run Than a Gas Boiler?
Sometimes. At current standard-tariff prices, good heat-pump performance can put it around the cost of a new gas boiler, while a suitable heat-pump tariff can make it cheaper. Poor seasonal performance or an expensive tariff can move it the other way.
Ofgem's average direct-debit cap for 1 July to 30 September 2026 is 26.11p/kWh for electricity and 7.33p/kWh for gas. If a gas boiler converts 90% of its bought gas into useful heat, each useful kWh costs about 8.1p before standing charges. A heat pump at a seasonal performance factor of 3.2 costs about the same:
26.11p electricity ÷ 3.2 seasonal performance = about 8.2p per useful kWh.
That is a break-even illustration, not an annual bill forecast. It leaves out standing charges, circulation pumps, hot-water differences and tariff variation. If removing gas lets you cancel the gas account, avoiding its standing charge helps the heat-pump side. If the home needs high flow temperatures and the heat pump only achieves a low seasonal performance, it hurts it.
Energy Saving Trust's current guidance reaches the sensible middle ground: on standard tariffs, heat-pump running costs can be similar to or slightly above a new gas boiler, while time-of-use heat-pump tariffs can reduce them significantly. Anyone promising one fixed saving without your heat demand, design SCOP and tariff is presenting arithmetic in fancy dress.
Which Costs More to Install?
A straightforward gas-boiler swap is usually the lower-cost installation. The flue, gas supply, condensate and system still need checking, but much of the existing arrangement may be reusable.
A proper heat-pump quote can include:
- room-by-room heat-loss calculations
- radiator and pipework assessment
- a hot-water cylinder and controls
- outdoor-unit base, drainage and pipe route
- electrical supply and protective devices
- planning/noise assessment and MCS paperwork
- commissioning at the designed flow temperature
The Boiler Upgrade Scheme currently offers £7,500 towards an eligible air-to-water heat pump in England and Wales. Eligible off-gas homes replacing oil or LPG can receive £9,000 until March 2027, but a mains-gas replacement remains at £7,500. The MCS installer applies the grant to the project, so eligibility should be confirmed in the quotation.
Which Homes Suit a Heat Pump?
A heat pump needs to deliver the home's heat loss at the outdoor design temperature while keeping water temperature as low as practical. It is a strong candidate where the property has:
- a suitable outdoor location with manageable noise and pipe routes
- emitters that can deliver the required room heat at the design flow temperature
- space for an appropriate hot-water cylinder
- pipework capable of the required water flow
- a homeowner comfortable with steadier, longer operating periods
A new build is the obvious place to design around low-temperature heating from day one. Existing and older homes can also work well. Insulation is useful because it reduces demand for any heating system, but a home does not need to resemble a vacuum flask before a heat pump is allowed through the gate.
A solid-wall, single-glazed or listed property may need a more careful project. The answer could involve selective fabric work, larger emitters or a higher-temperature design. Our older-home heat pump service brings those decisions together for Lincolnshire properties. In a few homes the disruption and cost do not make sense. Saying that openly makes the recommendation more credible, not less.
When Can a Gas Boiler Still Make Sense?
A gas boiler can remain a practical choice when the customer wants a low-disruption replacement, there is no acceptable outdoor-unit location, cylinder space is genuinely unavailable, or the heat-pump-enabling work is disproportionate to the wider plan for the property.
It may also be a timing decision. A failed boiler in winter creates a different decision window from a homeowner planning two years ahead. If a working boiler is retained, it is still worth improving controls, lowering the flow temperature where the system allows and avoiding unnecessary oversizing.
Most importantly, I will not force a heat pump onto someone who does not want one. The customer lives with the heating. My job is to explain the consequences of each option and design the chosen system properly.
Do Heat Pumps Need Bigger Radiators?
Not automatically. A radiator gives less heat as the average water temperature gets closer to the room temperature. The survey therefore compares each room's heat loss with what its existing radiator can emit at the proposed heat-pump flow temperature.
Some radiators are already oversized. Some rooms need a larger double-panel radiator. Others may benefit from a fan-assisted emitter or targeted fabric improvement. The correct answer is a room-by-room schedule, not replacing every radiator because somebody on the internet enjoyed ordering rectangles.
Lower flow temperature improves heat-pump efficiency. It can also help a condensing gas boiler recover more latent heat from the flue gases, so emitter and control improvements are not wasted if you choose gas now and revisit a heat pump later.
Hot Water, Cylinders and Showers
A combi boiler heats domestic hot water as you use it, so there may be no cylinder. An air-to-water heat pump normally heats stored water. Replacing a combi therefore needs a conversation about where the cylinder will go, how large it should be, its reheat strategy and how the household uses showers and baths.
Stored water can provide excellent multi-outlet performance when the incoming main, cylinder and pipework are designed for it. The cylinder is not just an unfortunate cupboard guest. It can allow hot-water production to be scheduled around tariffs and separate the rate of heat generation from a busy ten-minute shower period.
Comfort, Noise and Controls
A good heat pump usually runs for longer at lower water temperatures, following outdoor conditions through weather compensation. Radiators may feel warm rather than fiercely hot, while room temperature stays steadier. Turning it off for most of the day and demanding a fast evening recovery can undermine that design.
A gas boiler can also provide even comfort with good modulation and controls, but its higher available output makes fast recovery easier. Oversized boilers with high minimum outputs can short cycle in mild weather, so “more kW” is not automatically an upgrade.
Heat pumps make outdoor fan and compressor noise; boilers make combustion, pump and flue noise. Correct siting, anti-vibration details, hydraulics and commissioning matter more than brochure adjectives for both.
Maintenance and Lifespan
Both systems need sensible maintenance. A gas boiler needs a Gas Safe registered engineer and combustion/flue checks. A heat pump needs its outdoor coil, fan, refrigerant circuit, system water, controls, filters/strainers and operating data checked by someone competent for the system.
Ask who will support the installation after year one. A wonderful seasonal-performance calculation is less comforting if nobody answers when the system displays a fault in January.
How I Would Decide
- Calculate the room-by-room and whole-house design heat loss.
- Record existing emitters, pipe sizes, controls and achievable flow temperature.
- Discuss hot-water demand and identify a realistic cylinder position.
- Assess outdoor-unit location, noise, drainage and planning.
- Compare the gas installation with the complete heat-pump project after the confirmed grant.
- Model running cost using the proposed heat pump's seasonal performance and tariffs the homeowner can actually access.
- Consider disruption, carbon, comfort, length of ownership and future solar/battery plans.
That process can recommend either system. What it should not recommend is choosing from a national average while ignoring the house standing in front of us.
Frequently Asked Questions
Is a heat pump better than a gas boiler?
A well-designed heat pump is a strong long-term choice for many homes, but there is no universal winner. Property heat loss, emitters, hot-water demand, space, tariff, budget and the homeowner's priorities decide which system fits.
Is a heat pump cheaper to run than a gas boiler?
It can be. At current capped unit rates, a heat pump needs seasonal performance of roughly 3.2 to match a 90% efficient gas boiler before standing charges. Good design and a suitable time-of-use tariff can improve the heat-pump result; poor performance can worsen it.
Is a gas boiler cheaper to install than a heat pump?
A straightforward gas-boiler replacement is usually cheaper before grants. Heat-pump projects can include heat-loss calculations, emitter changes, a cylinder, electrical work and outdoor-unit preparation. The £7,500 Boiler Upgrade Scheme grant can materially reduce an eligible heat-pump quote.
Can a heat pump work in an old house?
Yes. Age alone does not rule a property out. The survey must establish heat loss, available emitter output, pipework, flow temperature and any worthwhile fabric improvements. Some old homes work with modest changes; others need a larger project.
Do heat pumps need bigger radiators?
Not always. Existing radiators may already be large enough, particularly after insulation improvements or at a suitable design flow temperature. A room-by-room heat-loss and emitter check should identify only the radiators that genuinely need changing.
Can a heat pump replace a combi boiler?
Yes, but an air-to-water heat pump normally stores domestic hot water in a cylinder rather than producing it instantly like a combi. The project therefore needs cylinder space and a hot-water design as well as space heating.
Should I replace a working gas boiler with a heat pump?
There is no need to manufacture an emergency. Use the time to obtain a proper survey, understand grants and plan any emitter or cylinder work. Replacement can make sense for carbon, comfort or long-term plans, but it should be an informed decision.
Does a heat pump keep a house warm in freezing weather?
A correctly sized system should meet the home's design heat loss at the chosen outdoor design temperature. Output and efficiency change as outdoor temperature falls, so the installer must use manufacturer performance data and allow for defrost rather than sizing from the badge alone.
Compare Both Options for Your Home
Vector Heat installs boilers and survey-led heat pumps, so the first conversation does not need a predetermined winner. We can explain the design, grant and running-cost assumptions behind each route.