Heat Pump vs Gas Boiler for a Cambridge Home — Cost, Comfort, Space and Carbon
Last reviewed: 2 October 2026
Money is only one part of the choice. This comparison takes a typical Cambridge semi through fifteen years of costs, then compares comfort, space, maintenance and carbon, with the city's cold, dry winters in mind.
The home in this comparison
A 1930s semi in Chesterton or Arbury with filled cavity walls and a topped-up loft, needing about 12,000 kWh of heat a year. Its old gas boiler needs replacing, so the choice is between a new gas boiler and an air source heat pump.
1. Total cost over 15 years
Assumptions: October 2026 prices held flat (electricity about 26p/kWh, gas about 8p/kWh, gas standing charge about £108 a year); gas boiler 90% efficient; heat pump seasonal efficiency 3.1, a realistic figure for Cambridge’s frostier climate; annual servicing for both.
| Gas boiler | Heat pump (standard tariff) | Heat pump (heat pump tariff, ~18p) | |
|---|---|---|---|
| Installed price | £3,000 | £2,600 after £7,500 grant | £2,600 after grant |
| Fuel over 15 years | £15,945 | £15,285 | £10,455 |
| Gas standing charge | £1,620 | — | — |
| Servicing | £1,500 | £2,250 | £2,250 |
| 15-year total | £22,065 | £20,135 | £15,305 |
The heat pump is about £1,900 cheaper over fifteen years on a standard tariff, and about £6,750 cheaper on a heat pump tariff.
Cambridge’s colder winters narrow the gap slightly compared with milder cities, because the heat pump works a little harder. Good design closes most of it: a system running at 45°C rather than 55°C can lift seasonal efficiency well above 3.1.
2. Comfort
Gas boiler: heats quickly, which suits short bursts morning and evening. Rooms can swing between too hot and too cold.
Heat pump: runs longer at a lower temperature, keeping the house at a steady warmth. Radiators feel warm rather than hot. Most owners find it more comfortable once they stop switching it on and off.
Hot water: a combi boiler gives unlimited hot water on demand. A heat pump heats a stored cylinder, which is plenty for most households if it’s sized properly, but very long consecutive showers can run it down.
3. Space
Gas boiler: a combi fits in a kitchen cupboard and needs no cylinder.
Heat pump: needs an outdoor unit (roughly the size of a large suitcase standing on its side) plus an indoor hot water cylinder, usually 180–250 litres. In Cambridge’s compact Victorian terraces, finding a cylinder cupboard is often the hardest part of the job. Semis like this one usually have room.
4. Upkeep
| Gas boiler | Heat pump | |
|---|---|---|
| Annual service | About £100, gas safety check | About £150, refrigerant and system check |
| Typical lifespan | 10–15 years | 15–20 years |
| Common issues | Ignition, flue, pressure | Sensors, controls, outdoor fan |
Cambridge Water’s very hard chalk water — roughly 286–295 mg/l of calcium carbonate across the city — affects both systems. Scale builds in boiler heat exchangers and in cylinder coils alike. A heat pump-rated cylinder with a large coil, plus a scale reducer, keeps the heat pump’s hot water efficient.
Because heat pumps tend to last longer, the gas option has a fair chance of needing a second boiler within fifteen years. That isn’t in the cost table.
5. Carbon
Burning natural gas releases roughly 0.18 kg of CO₂ per kWh. UK grid electricity currently averages around 0.2 kg per kWh, and that figure keeps falling as more wind and solar come online.
For this home:
- Gas boiler: about 13,300 kWh of gas a year, or roughly 2.4 tonnes of CO₂
- Heat pump: about 3,900 kWh of electricity a year, or roughly 0.8 tonnes, and falling each year
That’s around a two-thirds cut straight away.
Where the gas boiler still makes sense
Honestly, there are cases:
- A very small flat with no room for a cylinder or outdoor unit (though an air-to-air heat pump, now eligible for a £2,500 grant, may solve this)
- A listed building where no acceptable unit position can be found
- If you plan to move within a year or two and don’t want the disruption
For most Cambridge houses, though, the heat pump comes out ahead on cost over time, as well as on carbon and comfort.
Related reading
See what a heat pump would look like in your Cambridge home
The mechanism is the same in every UK home; the design is specific to yours. Our team carries out a free in-home survey including a full room-by-room heat-loss calculation, identifies the system size and configuration that fits your property, and provides a written quote with the £7,500 BUS grant already deducted.
You'll see the actual figure you'd pay — not an estimate — and the projected efficiency for your specific install.