You’re probably asking the same questions most homeowners ask when it comes to trying to decide between a heat pump or a new gas boiler.
The table below cuts through the noise and gives you a clear, side-by-side look at how air source heat pumps and gas boilers compare across the things that matter most, from running costs and efficiency to installation requirements and long-term value.
Category
💨 Air source heat pump
ASHP — monoblock or split unit
🔥 Gas boiler
Combi or system boiler
Costs
Supply & install cost
£8,000 – £15,000 BUS grant: −£7,500
£1,500 – £4,000
Annual running cost (avg UK home)
£900 – £1,400
£700 – £1,200
Servicing & maintenance
£100 – £200 / year
£80 – £150 / year
Expected lifespan
20 – 25 years
10 – 15 years
Efficiency & performance
Efficiency rating
SCOP 2.5 – 4.5 (250 – 450%)
AFUE 85 – 94%
Performance in cold weather
Reduces below −5 °C
Unaffected by outdoor temp
Hot water production
Via separate cylinder (slower reheat)
Instant (combi) or cylinder
Flow temperature
35 – 55 °C (lower is more efficient)
60 – 80 °C
Installation & suitability
Best suited to
Well-insulated homes; EPC C or above
Most existing UK homes
Space required
Outdoor unit + indoor cylinder/plant
Wall-mounted unit (compact)
Planning permission
Usually permitted development
Not required
Ideal heating distribution
Underfloor heating or oversized radiators
Standard radiators
Off-gas-grid suitability
Excellent
Not applicable
MCS certification required
Yes — for BUS grant
Gas Safe registered installer
Environmental
Carbon emissions
Low — grid-powered
High — fossil fuel combustion
Future-proofing
Aligns with 2035 gas boiler phase-out
Subject to future regulation
EPC impact
Improves rating
Neutral to minor improvement
Renewable energy compatible
Yes — pairs well with solar PV
No
Grants & policy
Government grant available
BUS: £7,500 (2025)
None
ECO4 / Warm Homes eligible
Yes — for qualifying households
Partial (insulation measures only)
2035 phase-out
Not affected
New installs banned from 2035
Verdict
Best for
✓ New builds & well-insulated homes
✓ Off-gas-grid properties
✓ Long-term cost & carbon savings
✓ Households claiming BUS grant
✓ Older, less-insulated homes
✓ Lower upfront budget
✓ Existing radiator systems
⚠ Short-term solution only
Advantage
Neutral / consider
Disadvantage
Info / requirement