Air Source vs Ground Source Heat Pumps: Which Is Right for You?
Compare air source and ground source heat pumps to decide which type works best for your property, budget, and heating needs in 2025.
Quick Comparison
| Air Source | Ground Source | |
|---|---|---|
| Installation cost | £10,000-£15,000 | £18,000-£28,000 |
| BUS grant | £7,500 | £7,500 |
| Your cost after grant | £2,500-£7,500 | £10,500-£20,500 |
| Efficiency (COP) | 2.5-3.5 | 3.5-4.5 |
| Space required | Small outdoor unit | Large garden for ground loops |
| Installation time | 1-2 days | 3-5 days |
| Best for | Most UK homes | Large properties with land |
What Is an Air Source Heat Pump?
An air source heat pump (ASHP) extracts heat from outdoor air — even in cold temperatures — and transfers it inside your home. Think of it as a reverse refrigerator.
How It Works
- Outdoor unit absorbs heat from the air
- Refrigerant liquid carries the heat indoors
- Heat is compressed to increase temperature
- Warm air or water is distributed through radiators, underfloor heating, or air vents
ASHPs work efficiently even when outdoor temperatures drop to -15°C, making them suitable for UK winters.
What Is a Ground Source Heat Pump?
A ground source heat pump (GSHP) extracts heat from the ground using pipes buried in your garden. The ground stays at a constant temperature year-round (about 10-15°C), making GSHPs very efficient.
How It Works
- Underground pipes (ground loops) filled with antifreeze solution absorb heat from the soil
- Fluid circulates back to the heat pump indoors
- Heat is compressed to increase temperature
- Heat is distributed through your heating system
Two types of ground loops: Horizontal (trenches in large gardens) or vertical (boreholes drilled deep underground).
Air Source Heat Pumps: Pros & Cons
✓ Advantages
- Lower upfront cost (£2,500-£7,500 after BUS)
- Quick installation (1-2 days)
- Works in most properties
- No garden excavation required
- Easier to maintain
✗ Disadvantages
- Slightly lower efficiency than GSHPs
- Performance drops in extreme cold
- Outdoor unit can be noisy (50-60dB)
- Visible outdoor unit may affect aesthetics
- Higher running costs than GSHPs
Ground Source Heat Pumps: Pros & Cons
✓ Advantages
- Higher efficiency (lower running costs)
- Consistent performance year-round
- No visible outdoor unit
- Quieter operation
- Longer lifespan (25+ years)
✗ Disadvantages
- Much higher upfront cost (£10,500-£20,500 after BUS)
- Requires large garden or space for drilling
- Longer installation (3-5 days)
- Garden disruption during installation
- Not suitable for small properties
Running Costs Comparison
Based on a typical 3-bedroom semi-detached house:
Old Oil Boiler
£1,800/year
Typical annual heating cost
Air Source Heat Pump
£900/year
50% saving vs oil
Ground Source Heat Pump
£700/year
60% saving vs oil
*Estimates based on average UK energy prices 2025. Actual costs vary by property size, insulation, and usage.
Which Heat Pump Should You Choose?
Choose Air Source if:
- You want lower upfront costs
- You have limited outdoor space
- You want quick installation
- You live in a typical UK property
- You're on a tighter budget
Choose Ground Source if:
- You have a large garden or land
- You want the most efficient system
- You can afford higher upfront costs
- You want minimal noise
- You're thinking long-term (25+ years)
Payback Period
How long until your investment pays for itself through energy savings?
Air Source Heat Pump
Your cost after BUS: £5,000 (average)
Annual savings vs oil: £900
Payback: 5-6 years
Ground Source Heat Pump
Your cost after BUS: £15,000 (average)
Annual savings vs oil: £1,100
Payback: 13-14 years
Get £7,500 Towards Your Heat Pump
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