Heat Pump vs Gas Boiler: Which Saves More?
Choosing between a heat pump and a gas boiler is one of the biggest heating investment decisions you'll make. Both technologies work, but they operate very differently and have vastly different running costs. This guide breaks down the real numbers so you can calculate which system will save you the most money over 15 years.
How They Work Differently
A gas boiler burns natural gas to create heat directly. A heat pump (usually air-source) extracts heat from outdoor air using electricity and a refrigerant cycle. Think of it as reversing an air conditioner—instead of removing heat from inside, it pulls heat from outside and pumps it indoors.
Efficiency Comparison
| Metric | Gas Boiler | Heat Pump (SCOP 3.5) |
|---|---|---|
| Efficiency rating | ~90% (modern) | ~350% (COP 3.5) |
| Heat output per kWh input | 0.90 kWh | 3.5 kWh |
| Works at -15°C? | Yes, full power | Yes, ~70% power |
| Loses heat in chimney? | Yes, 10% | No loss |
| Electricity needed? | Ignition only | Full cycle |
A heat pump's COP (Coefficient of Performance) of 3.5 means it delivers 3.5 kWh of heat for every 1 kWh of electricity used. A gas boiler can never exceed 100% efficiency (1 kWh heat per 1 kWh fuel). That's physics.
Annual Running Costs (15 kW heating need)
| System | Annual Consumption | Energy Cost | CO₂ per year |
|---|---|---|---|
| Gas boiler (90% eff.) | 16,700 kWh gas | EUR 1,340 | 3.3 tonnes |
| Heat pump (COP 3.5) | 4,300 kWh electricity | EUR 688 | 1.1 tonnes |
| Annual savings | — | EUR 652 | 2.2 tonnes less |
per year with heat pump vs gas boiler (assuming 15 kW heating demand and COP 3.5)
Installation & Upfront Costs
- Gas boiler: EUR 2,500–5,000 installed (simple, most homes have gas connection)
- Heat pump: EUR 10,000–18,000 installed (outdoor unit, refrigerant lines, larger indoor radiators or underfloor heating needed)
- Heat pump + insulation upgrade: EUR 15,000–25,000 (if you also upgrade windows/insulation for better efficiency)
Payback Period & 15-Year ROI
| Scenario | Payback Period | 15-Year Savings | Total Cost |
|---|---|---|---|
| Gas boiler replacement only | N/A | €0 | €5,000 |
| Heat pump (standard install) | 15 years | EUR 9,780 | €10,000 |
| Heat pump + insulation | 18 years | EUR 12,200 | €15,000 |
The heat pump's payback period is long—but once it breaks even, every additional year saves you EUR 652. If you plan to stay in your home 18+ years, the heat pump wins financially. Plus, you get lower carbon emissions and potential government grants (many EU countries offer heating retrofit subsidies).
When Gas Boiler Makes Sense
- You're only staying 5–10 more years
- Your home is poorly insulated (heat pump efficiency drops below COP 2.5)
- No outdoor space for the heat pump unit
- You want immediate, familiar technology with low upfront cost
When Heat Pump Wins
- You'll stay 15+ years—payback period is justified
- Your home is reasonably insulated (U-value < 1.0 W/m²K)
- You want lower carbon emissions (EU climate targets)
- Government grants are available in your region (often EUR 3,000–8,000 rebates)
- You plan to combine with solar panels (heat pump + PV = huge savings)
A heat pump in a poorly insulated home will struggle and run constantly. Before investing EUR 15,000 in a heat pump, upgrade your insulation (windows, roof, walls) first. This reduces your heating demand from 15 kW to 8 kW, making the heat pump much more cost-effective.
The real decision isn't heat pump vs gas boiler—it's about your timeline, your home's insulation, and whether you can access government grants. Run your own calculation: Get quotes for both, check your annual heating costs on your bill, and use the EUR 652 annual savings figure to calculate your payback period.
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