The most important decision for your heat pump installation. Here's everything you need to know about both systems for Dorset properties.
95% of our Dorset clients choose air source due to lower cost (£8-18k vs £20-45k), no groundworks, and faster installation (2-3 days vs 2-3 weeks). Modern air source systems achieve SCOP 4.5-5.0 - excellent efficiency at fraction of the cost.
Choose ground source if: You have large gardens (200m²+), plan to stay 20+ years, want maximum efficiency, and budget allows £20k-£45k. Otherwise, air source delivers 90% of the benefits at 50% of the cost.
The biggest difference: installation costs and long-term payback
For typical 4-bed home (well-insulated)
For typical 4-bed home (well-insulated)
Ground source saves £200-£300/year on running costs vs air source, but costs £12,000-£27,000 more upfront (after grants). At £250/year savings, payback takes 48-108 years. Most choose air source for this reason.
Every 1kW of electricity produces 3.5-5kW of heat
Every 1kW of electricity produces 4.5-5.3kW of heat
Dorset's mild maritime climate (average winter 5-7°C) is ideal for air source heat pumps. They operate in their sweet spot (COP 4.0+) for 90% of the year. Ground source's efficiency advantage is minimal in this climate compared to colder regions.
| Factor | Air Source | Ground Source |
|---|---|---|
| Installation Time | 2-3 days ⭐ | 2-3 weeks |
| Space Required | 1-2m² ⭐ | 150-200m² |
| Groundworks | None ⭐ | Extensive |
| Planning Permission | Rarely ⭐ | Sometimes |
| Garden Disruption | Minimal ⭐ | Significant |
| Installation Cost | £8-18k ⭐ | £20-45k |
| Running Cost (annual) | £800-1,200 | £600-900 ⭐ |
| Efficiency (SCOP) | 3.5-5.0 | 4.5-5.3 ⭐ |
| Lifespan | 15-20 years | 25-50 years ⭐ |
| Maintenance | Annual service | Minimal ⭐ |
| Noise | 35-45dB | Very quiet ⭐ |
| Suitability | All properties ⭐ | Large gardens only |
⭐ = Advantage in this category
95% of Dorset homeowners choose air source because:
Ground source heat pumps are more efficient, typically achieving SCOP ratings of 4.5-5.3 vs air source 3.5-5.0. This is because ground temperature is more stable year-round (8-12°C). In practice, ground source can be 20-30% more efficient, but higher installation costs mean payback takes 15-20 years vs air source.
Air source systems cost £8,000-£18,000 installed. Ground source costs £20,000-£45,000 depending on ground collector type. After up to £9,000 BUS grant: air source £500-£10,500, ground source £12,500-£37,500. Ground source costs 2-3x more due to groundworks and drilling.
Horizontal ground loops need 150-200m² of garden space (1.5-2x your home's floor area). Vertical boreholes need minimal space (1-2m²) but cost £10,000-£15,000 extra for drilling. Most Dorset properties lack space for horizontal loops, making air source the practical choice.
Both work excellently in Dorset's mild maritime climate. Air source modern systems perform well down to -25°C, far colder than Dorset winters (rarely below -5°C). Ground source offers marginally better efficiency, but air source's lower cost and simpler installation make it the popular choice for 95% of Dorset homeowners.
Ground source systems last 25-50 years (ground loops can last 100+ years), while air source lasts 15-20 years. However, air source units are cheaper to replace (£4,000-£8,000 vs £10,000-£15,000), and technology improves rapidly. Many prefer replacing air source every 15 years with latest tech over 50-year ground source commitment.
We'll assess your property, garden space, and budget to recommend the perfect system - backed by 15+ years of experience installing both types across Dorset.