Comparison · Heating, ventilation and cooling
Heat pump versus gas boiler
Last updated 25 October 2026 · 1 source listed · Reading time about 3 minutes
Short answer
A heat pump moves heat from outside to inside and typically delivers several units of heat per unit of electricity, but it works best with good insulation and low-temperature emitters. A gas boiler is a simpler swap with familiar controls, but ties you to fuel price and policy exposure. The answer depends on your building, local energy prices, available incentives and long-term plans.
Who this is for: A homeowner with a gas boiler nearing the end of its life who is deciding whether to stay with gas or switch to an electric heat pump.
What to evaluate
Insulation and heat loss
Heat pumps perform best in well-insulated homes where they can run at lower flow temperatures.
How to check: Review loft, wall and window insulation and ask for a heat loss calculation before choosing.
Emitters and pipework
Standard radiators sized for hot boilers may be too small for a heat pump's gentler output.
How to check: Ask which radiators need upsizing, or if underfloor heating is feasible.
Energy price relationship
Running cost depends on how electricity and gas prices compare in your area, and on the system's seasonal efficiency.
How to check: Model both options using your current tariff structure and ask about time-of-use rates.
Space and siting
Heat pumps need outdoor space and may need a cylinder indoors, whereas combination boilers are compact.
How to check: Mark a location for the outdoor unit and check distance rules to boundaries.
Cooling capability
Some heat pumps can also cool, offering summer comfort.
How to check: Ask whether the unit offers reversible operation and how cooling is distributed.
Policy and incentives
Grants, regulations and carbon rules vary and can alter the economics.
How to check: Check your government or utility programmes and any planned restrictions on fossil fuel boilers.
Comparison
| Factor | Heat pump | Gas boiler |
|---|---|---|
| Efficiency | Delivers multiple units of heat per unit of electricity | Converts most fuel energy into heat but cannot exceed full conversion |
| Installation | Often more extensive, with outdoor unit and possible emitter changes | Usually a straightforward swap |
| Running cost | Depends on electricity price and system design | Depends on gas price and efficiency |
| Comfort | Steady, lower-temperature heat over long periods | Quick, high-temperature bursts |
| Future exposure | Aligned with electrification and clean-grid plans | Subject to fuel price and regulatory change |
Decision worksheet
Rate up to three options against this guide’s own criteria. It runs in your browser and saves only on this device. It is a thinking aid, not a recommendation.
1. Have you checked each criterion?
0 of 6 criteria checked.
2. Compare options (0 = fails or unknown, 3 = meets it well)
| Criterion | |||
|---|---|---|---|
| Insulation and heat loss | |||
| Emitters and pipework | |||
| Energy price relationship | |||
| Space and siting | |||
| Cooling capability | |||
| Policy and incentives | |||
| Total (max 18) | 0 | 0 | 0 |
Questions to ask before you commit
- How does the installer estimate running cost for each option under my tariff?
- Which radiators or pipes change for the heat pump design?
- Where will the outdoor unit go, and does it meet distance and noise rules?
- Is my electrical supply adequate, or does it need upgrading?
- What incentives or regulations apply to each option where I live?
- How will hot water be supplied and stored?
- What does servicing involve for each option?
Typical trade-offs
Switching now versus waiting for the boiler to fail
- Upside
- Planned replacement allows careful design and time to apply for incentives.
- Downside
- Replacing a working boiler early wastes remaining life.
Hybrid system versus full replacement
- Upside
- A hybrid uses a heat pump most of the time with boiler backup.
- Downside
- Two systems add complexity and cost.
Larger radiators versus underfloor heating
- Upside
- Larger radiators are cheaper and less disruptive.
- Downside
- They take wall space and may look different.
Common mistakes
- Assuming a heat pump fits any home unchanged. Poor insulation or small emitters can undermine results.
- Comparing only installation cost. Include running cost, maintenance and the likely lifespan.
- Ignoring hot water needs. Cylinder size and temperature settings affect efficiency.
- Failing to check electrical capacity. Panel or supply upgrades can add cost and delay.
Related questions
Will a heat pump make my home cold?
Not if it is properly sized and installed. Heat pumps tend to deliver steady, lower-temperature heat for long periods rather than short bursts, so they feel different from boilers. Rooms stay comfortable when radiators are large enough and the home retains heat. Complaints usually trace back to undersized units, poor insulation or incorrect settings. Ask the installer to show the design temperature and calculated room temperatures for your coldest conditions.
Are heat pumps noisy?
Modern units are designed to be quiet, usually comparable to a refrigerator or a quiet conversation at a short distance, but noise depends on model, load and placement. Siting away from bedroom windows and neighbours, and using anti-vibration mounts, reduces issues. Some regions set noise or distance limits for outdoor units. Ask for the manufacturer's sound data and request a demonstration of a similar installation if possible.
Do I still need a hot water cylinder?
Usually yes, because heat pumps heat water more gradually than combi boilers. A cylinder stores heated water and allows the pump to work efficiently, often with periodic higher-temperature cycles to control bacteria such as legionella. Space for the cylinder is a practical consideration, particularly in small homes. Some compact solutions exist, and an installer can advise on size based on household demand.
What if my current radiators are too small?
Options include replacing some radiators with larger or fan-assisted ones, improving insulation to reduce demand, or adding underfloor heating in key areas. The heat loss calculation indicates which rooms fall short. Sometimes only a few need upgrades, which keeps disruption moderate. Insist that the quote lists each room and emitter change, so the comparison with a boiler is fair.
Sources and further reading
These pages were reachable when we last checked. They informed definitions and rules referred to above; they do not endorse this guide. Where rules differ by country, check the authority for your location.
- ENERGY STAR — US EPA and Department of Energy, retrieved 27 October 2026
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