Gas Boiler or Heat Pump? Fifteen Years of Costs for a Leicester Semi
Last reviewed: 2 October 2026
For a three-bedroom Leicester semi, we compare fifteen years of installation, fuel and servicing costs for a new gas boiler and a heat pump, then test the result against rising gas and electricity prices.
Why fifteen years?
Fifteen years is roughly the life of a modern gas boiler and comfortably within the life of a heat pump (typically 15–20 years). It’s long enough for running costs to show their weight, and short enough to be a sensible planning horizon for most homeowners.
The home and the numbers
A three-bedroom interwar semi in Knighton or Western Park, needing about 11,000 kWh of heat a year. The gas boiler is due for replacement.
| Assumption | Gas boiler | Heat pump |
|---|---|---|
| Installed price | £3,000 | £10,800, minus £7,500 grant = £3,300 |
| Efficiency | 90% | Seasonal average 3.2 (East Midlands climate, good design) |
| Energy price | about 8p/kWh gas + £108/yr standing charge | about 26p/kWh (standard) or ~18p (heat pump tariff) |
| Servicing | about £100 a year | about £150 a year |
Prices are the Ofgem cap for October to December 2026, held flat for the whole period.
Fifteen-year totals
| Gas boiler | Heat pump, standard tariff | Heat pump, heat pump tariff | |
|---|---|---|---|
| Installation | £3,000 | £3,300 | £3,300 |
| Energy (15 years) | £14,610 | £13,575 | £9,285 |
| Gas standing charge (15 years) | £1,620 | £0 | £0 |
| Servicing (15 years) | £1,500 | £2,250 | £2,250 |
| Total | £20,730 | £19,125 | £14,835 |
On a standard tariff, the heat pump saves about £1,600 over fifteen years. On a heat pump tariff, about £5,900.
What if energy prices move?
Fifteen years of flat prices is unrealistic. Here’s the same comparison with a 20% change in each fuel, against the standard-tariff heat pump.
| Scenario | Gas boiler | Heat pump (standard) | Who wins |
|---|---|---|---|
| Gas up 20% | £23,652 | £19,125 | Heat pump by about £4,500 |
| Electricity up 20% | £20,730 | £21,840 | Gas by about £1,100 |
| Both up 20% | £23,652 | £21,840 | Heat pump by about £1,800 |
| Gas up 20%, electricity down 10% | £23,652 | £17,768 | Heat pump by about £5,900 |
On a heat pump tariff, the heat pump stays ahead in every scenario in this table. The only case where gas wins is electricity rising sharply while gas stays still, with the heat pump on a standard tariff.
Costs the table doesn’t show
- A replacement boiler. If the new gas boiler only lasts twelve years, you’ll buy another one inside the fifteen-year window.
- Leicester’s hard water. Severn Trent’s supply here is hard, roughly 220–280 mg/l of calcium carbonate. Scale builds in boiler heat exchangers and cylinder coils alike. A scale reducer protects either system.
- Space. A heat pump needs a hot water cylinder, which many Leicester terraces lost when combi boilers arrived. In a semi this is usually easy; in a two-bed terrace it can take some planning.
Where the gap is bigger
- Homes on electric storage heaters, common in Leicester flats and some post-war blocks, typically save over £1,000 a year by switching, though they need radiators and pipework installed.
- Homes on oil or LPG, on the edges of Aylestone and Birstall, can claim £9,000 instead of £7,500 on applications from 21 July 2026 to 31 March 2027.
- Lower-income households may get a heat pump free through Leicester City Council’s Warm Homes: Local Grant (household income under £36,000, EPC D to G). The fifteen-year comparison then becomes one-sided.
Where the gap is smaller
Large solid-walled Victorian homes, such as some of the villas in Stoneygate and Clarendon Park, need more heat and more radiator work. The heat pump still usually wins over fifteen years, but basic insulation — loft, draught-proofing, and suspended-floor insulation where practical — makes a bigger difference to the margin.
Next
See what a heat pump would look like in your Leicester 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.