What Is a Ground Source Heat Pump?
A ground source heat pump (GSHP) extracts low-grade heat from the ground via a buried collector loop and uplifts it to useful heating temperatures using a refrigeration cycle. Because ground temperatures in Cornwall stay between 9–12°C year-round — far more stable than the air — a GSHP runs at a higher Seasonal Coefficient of Performance (SCOP) than an air source unit: typically 4.0–4.8 vs 3.0–3.5 for ASHP. That difference compounds over a heating season into 20–35% lower running costs. Cornwall is genuinely well-suited to ground source: the Eden Project's geothermal drilling at Bodelva (3 miles from St Austell) is delivering geothermal heat to its biomes from depths around 5km, and shallower domestic borehole drilling is straightforward across most of mid and east Cornwall. The Boiler Upgrade Scheme covers GSHP at the same level as ASHP — £7,500, or £9,000 until March 2027 where you are replacing oil or LPG and have no mains gas connection — but because GSHP installations are more expensive (mainly due to the ground works), the grant takes a smaller percentage off the total. The trade-off is much lower running costs over a 25-year system life. For Cornwall farmsteads, smallholdings, and rural properties with paddock space (around 2.5x the floor area of the house, for horizontal loops) GSHP is often the optimal long-term choice.
Key Benefits
Benefits of Ground Source
SCOP 4.0–4.8
GSHP delivers 4.0–4.8 kWh of heat per kWh of electricity — vs 3.0–3.5 for ASHP. At Q2 2026 electricity prices, that's heating costs of around 5.4p/kWh vs 7.0p for ASHP.
25–30 Year System Life
The heat pump unit lasts 20–25 years. The buried ground loop lasts 50–100 years. Total cost of ownership across the system life is significantly lower than ASHP.
No External Unit
GSHP units sit indoors (typically in a utility room or plant room). No outdoor fan, no audible noise outside, no planning/visual issues — ideal for listed buildings and conservation areas.
Up To £9,000 BUS Grant
The same Boiler Upgrade Scheme bands apply as for ASHP — £7,500, or £9,000 until March 2027 where oil or LPG is replaced and there is no mains gas connection. CCS handles the full application — the grant comes off your invoice.
Cooling Capability
Reverse-cycle "passive cooling" through the ground loop costs almost nothing to run and gives you genuine summer cooling without an air conditioner. Useful for south-facing Cornwall homes.
Ground Source vs Air Source
GSHP: SCOP 4.0–4.8, ~5.4p/kWh heat, indoor unit (no outdoor noise), 50–100yr ground loop, but £25,000–£35,000 before grant and needs land or a borehole. ASHP: SCOP 3.0–3.5, ~7.0p/kWh, outdoor fan unit, £8,000–£14,000 before grant, fits almost any property. Both qualify for the same £7,500 BUS grant — GSHP wins on lifetime running cost where land allows; ASHP wins on upfront cost. Compare our /heat-pump-installation/ page for the air-source option.
Best for Off-Gas Rural Properties
For properties replacing oil or LPG with available paddock or borehole space, GSHP delivers lower running costs and longer service life than any other heating system.
Our Process
How It Works
Free Survey
We visit your property to assess your heating needs, measure heat loss, and discuss the best options for your home.
Design & Quote
We design a bespoke system, identify all eligible grants including the Boiler Upgrade Scheme (up to £9,000), and provide a transparent fixed-price quote.
Installation
Our MCS certified engineers install your system cleanly and efficiently, typically within 2–4 days, with minimal disruption to your home.
Aftercare
Full system handover, MCS certification, warranty registration, BUS grant application completion, and ongoing support when you need it.
GSHP Costs in Cornwall
A typical Cornwall GSHP installation costs £25,000–£35,000 before grant, depending on heat pump size, ground works, and property requirements. With the £7,500 BUS grant, net cost is £17,500–£27,500. Horizontal slinky loops (best when you have 2.5× the house floor area in clear paddock or garden) add £4,000–£8,000 of trenching and excavation. Vertical boreholes (used where land is limited or geology favours it) cost £15,000–£25,000 for typical 80–120m boreholes. The heat pump unit itself runs £5,500–£9,500 depending on output (8–17 kW most common in Cornwall). We carry out a full ground assessment, MCS-compliant heat-loss calculation, and BUS grant application as part of every quote.
Which ground loop suits your Cornwall property?
The heat pump indoors is the easy part; the ground array decides the cost and what your plot can take.
| Collector | What it needs | Where it suits |
|---|---|---|
| Horizontal trenches | Open, diggable ground — roughly 2.5 times the heated floor area, trenched at about 1.2-1.5 m depth | Farmsteads, smallholdings and rural plots with paddock or field space |
| Slinky coils | Shorter trench runs than straight pipe for the same collector length | Plots with land but limited trench length; the usual Cornwall compromise |
| Vertical boreholes | Drilling rig access; typically 90-150 m per borehole, several metres apart | Small gardens, listed settings and anywhere a lawn cannot be lifted |
Cornish geology matters here. Much of the county sits on granite and metamorphic killas rather than soft sediment, so boreholes are drilled into hard rock: slower going than in clay, and the reason borehole quotes vary more between properties here than almost anywhere in England. Granite conducts heat well once you are in it, which is why the depth per kW can be lower than a UK average figure suggests. The Eden Project's own geothermal well at Bodelva, drilled to around 4.5-5 km, is the deep end of the same principle.
What a ground source system costs in Cornwall
| Element | CCS guide price |
|---|---|
| Heat pump, cylinder, controls, commissioning (as for an air source job) | £11,500-£16,800 |
| Ground array — trenches or slinkies, including groundworks | £6,000-£14,000 |
| Ground array — vertical boreholes | £12,000-£22,000 |
| Typical complete installation | £18,000-£32,000 before grant |
| After the Boiler Upgrade Scheme | £9,000-£24,500 (at £7,500) · £9,000-£23,000 (at £9,000, oil or LPG with no gas main) |
Ground source costs more to install than air source and less to run. Where it pays back is a property with a long heating season, a large heat demand and land for a horizontal array — a Cornish farmhouse rather than a two-bedroom terrace.
Ground source vs air source, decided honestly
| Ground source | Air source | |
|---|---|---|
| Typical seasonal efficiency (SCOP) | 4.0-4.8 | 3.0-3.5 |
| Installed cost | £18,000-£32,000 | £11,500-£16,800 |
| Boiler Upgrade Scheme | £7,500, or £9,000 off the gas grid | £7,500, or £9,000 off the gas grid |
| Outdoor unit | None — the heat pump sits indoors | One outdoor unit (two permitted on a detached house) |
| Planning | Permitted development with no Part 14 limits | Class G limits, including a 37.0 dB(A) noise test |
| Needs land | Yes, unless you drill | No |
Because the grant is now the same for both, the old argument that ground source is penalised on funding has gone. The decision is land, disruption and how long you plan to own the house.
Planning and permissions
Ground source heat pumps are permitted development under their own class in Part 14 of the General Permitted Development Order, with none of the size, siting or noise limits that apply to an air source unit — there is no outdoor fan to assess. That makes ground source the simpler route in a conservation area, inside the Cornwall and West Devon Mining Landscape World Heritage Site, or on a listed property, where an external air source unit needs permission. Listed buildings still need consent for works that affect their character, and a borehole needs rig access and a sensible spoil plan. We confirm all of this at the survey.
How a Cornwall ground source installation runs
- Survey and heat loss — room-by-room calculation, emitter schedule, and an assessment of what your ground can take.
- Array design — trench, slinky or borehole, sized to the heat demand rather than to a rule of thumb.
- Fixed quote and grant — we apply for the Boiler Upgrade Scheme voucher and deduct it from the invoice.
- Groundworks — trenching or drilling, pipe laying, pressure testing and reinstatement.
- Installation and commissioning — heat pump, cylinder and controls, then MCS certification and the network operator notification.
Comparing the two technologies in detail? Our Cornwall ground source guide covers geology, loop maths and performance data, and heat pumps Cornwall sets out the air source route.
Trusted Partners
Brands We Install
Areas We Cover for Ground Source
We install ground source across Cornwall. Click your area for local information and a free quote.
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Common Questions
Frequently Asked Questions
01 How much does it cost to fit a ground source heat pump in Cornwall?
02 Is ground source better than air source in Cornwall?
03 Do I need planning permission for a heat pump in Cornwall?
04 What grant can I get for a heat pump in Cornwall?
05 What are the downsides of a ground source heat pump?
06 How much land do you need for a ground source heat pump?
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