Compare heat pump vs gas boiler running costs, understand SCOP efficiency ratings, calculate monthly bills, and discover £7,500 BUS grant savings.
Calculate annual running costs for your property:
Average monthly costs based on typical UK homes with SCOP 3.0 heat pump and current price cap electricity (24.5p/kWh):
| Property Type | Heat Demand (kWh/year) | Electricity Used (kWh/year) | Heat Pump Annual Cost | Heat Pump Monthly | Gas Boiler Annual | Gas Boiler Monthly | Difference |
|---|---|---|---|---|---|---|---|
| 1-Bed Flat | 4,000 | 1,333 | £327 | £27 | £294 | £25 | +£33/year (10% more) |
| 2-Bed Terrace | 6,000 | 2,000 | £490 | £41 | £441 | £37 | +£49/year (11% more) |
| 3-Bed Semi | 9,000 | 3,000 | £735 | £61 | £661 | £55 | +£74/year (11% more) |
| 4-Bed Detached | 12,000 | 4,000 | £980 | £82 | £882 | £74 | +£98/year (11% more) |
| 5-Bed Large | 15,000 | 5,000 | £1,225 | £102 | £1,102 | £92 | +£123/year (11% more) |
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Current reality (January 2026): With electricity at 24.5p/kWh and gas at 6.24p/kWh (price cap), heat pumps cost 10-15% MORE to run than gas boilers for average SCOP 3.0 system. However, £7,500 BUS grant, lower carbon emissions, and future electricity price reductions vs rising gas prices make heat pumps still attractive long-term investment.
SCOP (Seasonal Coefficient of Performance) measures heat pump efficiency across entire heating season. COP measures instantaneous efficiency at specific conditions.
Manufacturers quote SCOP tested at 35°C or 45°C flow temp under ideal lab conditions. Real-world SPF (Seasonal Performance Factor) often 10-20% lower due to higher flow temps, colder weather, cycling losses. Typical UK home: SCOP 3.5 marketing claim → SPF 3.0 real-world. Always ask installer for realistic SPF estimate for YOUR home.
| Property Size | Heat Pump Size | Full Installation Cost | After £7,500 BUS Grant | Monthly Saving Needed (10yr payback) |
|---|---|---|---|---|
| 1-2 Bed Flat | 4-6 kW | £6,000-8,000 | £500-500 | £4-4 |
| 2-3 Bed Terrace | 6-8 kW | £8,000-10,000 | £500-2,500 | £4-21 |
| 3-4 Bed Semi | 8-10 kW | £10,000-12,000 | £2,500-4,500 | £21-38 |
| 4-5 Bed Detached | 10-13 kW | £11,000-15,000 | £3,500-7,500 | £29-63 |
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Reducing flow temp from 55°C to 45°C improves SCOP from 3.0 to 3.5 (17% efficiency gain = 17% cost reduction). Requires larger radiators or underfloor heating. Worth investing £1,000-2,000 in radiator upgrades during installation.
Insulate before installing heat pump. Loft + cavity wall insulation reduces heat demand by 30-40%, allowing smaller heat pump with lower flow temp. £2,000 insulation investment saves £200-300/year on heat pump running costs.
Smart control adjusts flow temp based on outdoor temperature. Mild day = lower temp = higher SCOP. Can improve average SCOP by 10-15%. Most modern heat pumps include this - ensure installer enables it.
Octopus Agile, E.ON Next Drive, Intelligent Octopus Go offer cheaper overnight electricity (7-15p/kWh vs 24.5p standard). Heat water overnight, use battery storage. Can save £150-300/year on heat pump costs.
Heat pumps most efficient running continuously at low output. Better to run 24/7 at 45°C than 12hrs/day at 60°C. Counterintuitive but proven - constant low temp more efficient than high temp bursts.
Oversized heat pump cycles on/off frequently (inefficient). Undersized runs constantly at high temp (also inefficient). Professional heat loss calculation essential - never guess or use "rule of thumb" sizing.
Heat pumps can be cheaper to run than gas in these scenarios:
3-bed semi, 9,000 kWh heat demand, SCOP 4.0 heat pump uses 2,250 kWh electricity = £551/year vs £661 gas = £110/year saving. Achievable with 35-40°C underfloor heating, excellent insulation.
Octopus Agile average 15p/kWh overnight vs 24.5p standard. 3-bed semi, SCOP 3.0, heat water overnight = effective cost £450/year vs £661 gas = £211/year saving.
Replacing oil boiler (9p/kWh) or LPG (10-12p/kWh). Heat pump at 24.5p electric ÷ SCOP 3.0 = 8.2p/kWh equivalent vs oil 9p = 9% cheaper. Plus avoid oil tank, deliveries, price volatility.
If electricity falls to 20p/kWh (possible with more renewables), heat pump SCOP 3.0 = 6.7p/kWh vs gas 6.24p = competitive. At 18p electric = heat pump clearly cheaper.
Current recommendation: Heat pumps make financial sense IF you can achieve SCOP 3.5+, have access to cheap overnight electricity, or replacing oil/LPG. For average SCOP 3.0 replacing gas, financial case weak (10% higher costs) but environmental case strong (70% carbon reduction) plus £7,500 grant and future-proofing justify installation.
Average running costs (SCOP 3.0, price cap rates): 1-bed flat £27/month (£327/year), 2-bed terrace £41/month (£490/year), 3-bed semi £61/month (£735/year), 4-bed detached £82/month (£980/year).
Comparison with gas (85% efficient boiler): Heat pumps currently 10-15% more expensive to run due to electricity/gas price gap (24.5p vs 6.24p). Need SCOP 3.5+ to match gas costs, SCOP 4.0+ to beat gas.
Key efficiency factors: Flow temperature (biggest impact - 55°C = SCOP 3.0, 45°C = SCOP 3.5, 35°C = SCOP 4.0), insulation quality (reduces heat demand allowing lower flow temp), radiator size (larger = lower temp possible), installation quality (poor install loses 20-30% efficiency).
Installation costs: £6,000-15,000 depending on property size. £7,500 BUS grant reduces to £500-7,500 out-of-pocket. Larger radiators/cylinder add £1,000-3,500.
Cost reduction strategies: Lower flow temperature to 35-45°C (17% saving), improve insulation first (30-40% heat demand reduction), use time-of-use tariff overnight (£150-300/year saving), weather compensation controls (10-15% improvement), continuous low-temp running not on/off cycling.
When heat pumps ARE cheaper: High SCOP 4.0 well-insulated homes (£110/year saving), time-of-use tariff users (£200+ saving), replacing oil/LPG not gas (9-25% cheaper), future electricity price falls to 18-20p/kWh.
Verdict: Running costs currently 10-15% higher than gas for average install, but £7,500 grant, 70% carbon reduction, 20-25 year lifespan, and future-proofing make heat pumps worthwhile investment despite higher running costs. Focus on achieving high SCOP 3.5+ through good design to minimize cost gap.